A little knowledge can be a bad thing. We see that with zoonotic diseases. Awareness is great. However, a little bit of awareness can be a problem if it’s enough make people paranoid but not enough to help them understand the real risks. This can lead to excessive and illogical responses (often ending with "...get rid of the cat").
Sound guidelines for preventing infections written by authoritative groups help a lot. An example of that is the recently updated Guidelines for the prevention and treatment of opportunistic infections in HIV-infected adults and adolescents. As a collaborative set of guidelines from the US Centers for Disease Control and Prevention (CDC), the National Institutes of Health, and the HIV Medicine Association of the Infectious Diseases Society of America, it carries a lot of weight - as it should.
It’s a monster of a document of 416 pages. Pet contact gets a little bit of room and probably just the right amount. Enough to say "it’s something to think about," "we’ve considered the issues" and "here are some basic things to consider.”
Here are their specific recommendations:
Hand-washing also should be recommended in association with the following activities: after handling pets or other animals, gardening or having other contact with soil; before preparing food or eating; and before and after sex (BIII).
HIV-infected individuals—particularly those with CD4 counts <200 cells/μL [i.e. people who have advanced disease]—should avoid direct contact with diarrhea or stool from pets (BIII).
Gloves should be worn when handling feces or cleaning areas that might have been contaminated by feces from pets (BIII).
HIV-infected individuals also should avoid other sources of Cryptosporidium oocysts as much as possible (BIII). These include working directly with people with diarrhea; with farm animals such as cattle and sheep; and with domestic pets that are very young or have diarrhea. If exposure is unavoidable, gloves should be used and practices for good hand hygiene observed.
The letters and numbers indicate the strength of evidence. B means there’s moderate evidence supporting the recommendation and III means it’s based mainly or exclusively on expert opinion, not research trials.
Note that nowhere does it say "get rid of the pet" or "avoid contact with animals altogether." Rather, it endorses the use of basic hygiene practices and common sense. In reality, all these recommendations could apply to any individual, not just people with HIV infection.
The preamble to the pet section includes a great statement:
Health-care providers should advise HIV-infected persons of the potential risk posed by pet ownership. However, they should be sensitive to the psychological benefits of pet ownership and should not routinely advise HIV-infected persons to part with their pets. Specifically, providers should advise HIV-infected patients of the following precautions.
…and those precautions are:
HIV-infected persons should avoid direct contact with stool from pets or stray animals. Veterinary care should be sought when a pet develops diarrheal illness. If possible, HIV-infected persons should avoid contact with animals that have diarrhea.
When obtaining a new pet, HIV-infected patients should avoid animals aged <6 months (or <1 year for cats) and specifically animals with diarrhea. Because the hygienic and sanitary conditions in pet-breeding facilities, pet stores, and animal shelters vary, patients should be cautious when obtaining pets from these sources. Stray animals should also be avoided, and specifically those with diarrhea.
Gloves should always be worn when handling feces or cleaning areas that might have been contaminated by feces from pets. Patients should wash their hands after handling pets and also before eating. Patients, especially those with CD4 cell counts < 200 cells/μL should avoid direct contact with all animal feces to reduce the risk for toxoplasmosis, cryptosporidiosis, salmonellosis, campylobacteriosis, E. coli infection, and other infectious illnesses. HIV-infected persons should limit or avoid direct exposure to calves and lambs (e.g., farms, petting zoos). Paying attention to hand hygiene (i.e., washing hands with soap and water, or alcohol-based hand sanitizers if soap and water are unavailable) and avoiding direct contact with stool are important when visiting premises where these animals are housed or exhibited.
Patients should not allow pets, particularly cats, to lick patients’ open cuts or wounds and should take care to avoid any animal bites. Patients should wash all animal bites, animal scratches, or wounds licked by animals promptly with soap and water and seek medical attention. A course of antimicrobial therapy might be recommended if the wounds are moderate or severe, demonstrate crush injury and edema, involve the bones of a joint, involve a puncture of the skin near a joint, or involve a puncture of a joint directly.
Patients should be aware that cat ownership may under some circumstances increase their risk for toxoplasmosis and Bartonella infection, and enteric infections [although I’d argue data supporting a broad statement of cat ownership increasing those risks that are largely lacking]. Patients who elect to obtain a cat should adopt or purchase an animal aged >1 year and in good health to reduce the risk for cryptosporidiosis, Bartonella infection, salmonellosis, campylobacteriosis, and E. coli infection.
Litter boxes should be cleaned daily, preferably by an HIV-negative, non-pregnant person; if HIV-infected patients perform this task, they should wear gloves and wash their hands thoroughly afterward to reduce the risk for toxoplasmosis. To further reduce the risk for toxoplasmosis, HIV-infected patients should keep cats indoors, not allow them to hunt, and not feed them raw or undercooked meat. Although declawing is not usually advised, patients should avoid activities that might result in cat scratches or bites to reduce the risk for Bartonella infection. Patients should also wash sites of cat scratches or bites promptly and should not allow cats to lick patients’ open cuts or wounds. Care of cats should include flea control to reduce the risk for Bartonella infection. Testing cats for toxoplasmosis or Bartonella infection is not recommended, as such tests cannot accurately identify animals that pose a current risk for human infection.
Screening healthy birds for Cryptococcus neoformans, Mycobacterium avium, or Histoplasma capsulatum is not recommended.
HIV-infected persons should avoid or limit contact with reptiles (e.g., snakes, lizards, iguanas, and turtles) and chicks and ducklings because of the high risk for exposure to Salmonella spp. Gloves should be used during aquarium cleaning to reduce the risk for infection with Mycobacterium marinum. Contact with exotic pets (e.g., nonhuman primates) should be avoided.
A local county newspaper had a front page headline about a zoning amendment that was approved to allow for a feeder rodent facility that will produce about 10 000 rodents a week (I know, apparently there aren't a lot of big things happen around here). Co-incidentally, a couple days later, I received an alert and fact sheet from the Ontario Ministry of Health and Longterm Care and the Office of the Chief Veterinarian of Ontario about Salmonella and feeder rodents because of an increase in human Salmonella Typhimurium infections in people in Ontario and a link to feeder rodents in some cases.
It’s not really a surprise. Large and sustained outbreaks of salmonellosis associated with feeder rodents have been reported for a while. These rodents are often produced at large facilities with hundreds of thousands of rodents, and if Salmonella gets in the facility, thousands (or millions) of biohazardous small-and-fuzzy snake snacks can get shipped around the world.
The fact sheet is attached here, and it contains good information about the standard reptile and rodent handling practices that I always keep coming back too: wash your hands, keep high risk people away, prevent cross-contamination of snake food with people food (e.g. don’t thaw frozen rodents in an open container in the fridge (yuck… but it happens) or cross contaminate kitchen surfaces) and other basic hygiene practices.
Infection control isn’t complicated, it’s often just ignored.
It doesn’t. (Just like monkeypox doesn’t come from monkeys.)
Cowpox is a viral infection and the natural reservoirs are actually rodents. Humans, cats and cows are amongst the more common "accidental hosts" - species that get infected sporadically but are not reservoirs. Contact with an infected rodent can result in transmission of cowpox to people. The virus can also come from an animal that gets cowpox from a rodent and then passes it on to a person, as a Dutch teenager found out...
A 17-year-old girl found a kitten in the ditch and picked it up. It was sick and ultimately died (probably not from cowpox). She later developed a skin lesion on her wrist, which progressed to red lumps over her arm. Not surprisingly, cowpox didn’t jump to mind when she saw her doctor, so it took a while before a diagnosis was made, but they figured it out eventually. Since cowpox infection is usually self-limiting in individuals with a normal immune system, the girl eventually got better without any specific treatment. It took a couple months, though, and left a scar.
Presumably the girl got cowpox from the kitten, which probably got cowpox from contact with an infected rodent. This is an unusual series of events, certainly, but far from unprecedented. Cats are one of the main non-reservoir species that are implicated in cowpox transmission to people, presumably because they get infected while hunting wildlife (e.g. rodents). Cowpox is a pretty rare infection in people and usually not very severe, so it’s nothing to be paranoid about, but it’s another reason to use good hygiene practices and keep cats from going outside and hunting.
FYI Cowpox got its name because infected cows often develop lesions on their udders, and it was a common infection of dairymaids in times when cows were milked by hand. This virus also features prominently in the development of the world's first vaccine in the late 1700s, as the cowpox virus itself was used as a vaccine against the deadly smallpox virus.
I'm just back from vacation (luckily, with no infectious disease stories to write), but now I have to catch up on a few posts. One easy one that was waiting for me in my inbox was about Salmonella and hedgehogs.
I've written before about biohazardous hedgehogs, and more details about the US 2011-2013 multi-state Salmonella outbreak were reported in a recent edition of CDC's Morbidity and Mortality Weekly Reports. The outbreak was identified through recognition of a cluster of infections in people caused by the same, historically rare strain of Salmonella Typhimurium. Finding a cluster of the same strain, especially a rare one, suggests that there might be a common source, so an investigation ensued. Here are some highlights:
- Twenty people from 8 states (Alabama, Illinois, Indiana, Michigan, Minnesota, Ohio, Oregon and Washington) were affected, although (as is typical) it's almost guaranteed that many more people were affected but not tested.
- Young people were more often affected, with the average age being 13. The age range spanned from less than 1 year to 91 years of age.
- Four people were hospitalized and one died.
- 14/15 (93%) people interviewed reported direct or indirect contact with a hedgehog. That's a pretty strong indication that hedgehogs might be involved, since that number is wildly disproportionate to the percentage of people in the general population that have contact with hedgehogs.
- Hedgehogs were obtained from various breeders, not from a single source.That's not uncommon since breeders often get animals from other breeders or suppliers and a point-source of infection further up the supply chain is likely.
For some reason, hedgehogs are high risk pets when it comes to Salmonella. High Salmonella shedding rates have been identified in studies of healthy hedgehogs and it's clear that contact with healthy carriers can lead to human infection. Hedgehogs should be considered alongside reptiles in terms of pets that should not be present in high risk households (households with kids less than 5 years of age, elderly individuals, pregnant women or people with compromised immune systems). Hedgehog owners should take care to avoid direct and indirect contact with feces and use good hygiene practices to reduce the risk of infection.
A recent report in the journal Infection (Chean et al. 2012) describes rat bite fever in a patient with AIDS. I’ve written about rat bite fever before, and it’s not really a surprising case report. Streptobacillus moniliformis, the bug that causes the disease, is found in the mouths of most rats (and in the mouths of dogs more often than we’ve previously assumed). Rat bite fever is uncommon but far from rare, and this report focuses on the fact that it was in an AIDS patient. The case report itself isn’t too noteworthy since we know infection with S. moniliformis can happen even in healthy people, and someone with AIDS is going to be at increased risk of any type of infection.
However, there are a few interesting aspects to this particular case. The report described a 30-year-old AIDS patient who had a rather prolonged course of disease with fever, aches, diarrhea and weight loss, with subsequent development of joint pain and swelling. A large battery of tests didn’t identify the underlying cause. Eventually, "it was noted that he had two pet rats, one of which bit the man on his right index finger 1 month prior to presentation." That should have been a "eureka!' moment for the physician. It doesn’t mean the disease was caused by the bite, but it made it clear that rat bite fever should be considered. The diagnosis was then made and the man received appropriate treatment.
While the clinical aspects of the case aren’t remarkable, there are some noteworthy points to consider:
- It wasn’t until re-evaluation that it was discovered that the patient had rats and had been bitten. It’s quick and easy for a doctor to ask “Do you have pets or have you had contact with animals?” and in a case like this, it could have sped up the diagnosis and appropriate treatment.
- The paper repeats the important statement that pet ownership rates among HIV/AIDS patients are similar to that of the general population. That’s also true for other groups at increased risk of infection.
- They say “Physicians need to be cognisant of this [pet/human] relationship in order to prevent missing the diagnoses of zoonotic infections in their patients.” That’s a critical step. It’s easy to do. It’s not often done right.
With the lingering NHL strike, TV networks are looking for replacement sports. One of my PhD students (who claims he doesn't spend too much time playing around on the internet but keeps coming up with these gems) sent me information about one sport that's not coming to a network near you.
Yes, it's ferret legging. That doesn't really seem like a sport to me...more like a fetish or something someone might do when they're really (really!) drunk. Yet, it apparently exists, evolving from its origins amongst Yorkshire coal miners to a not-much-broader audience.
The rules are pretty simple:
- Tie your pant legs securely around your ankles
- Let someone toss two ferrets down your pants.
- Secure your belt.
- Stand there until you can't take it any more.
"Clean the abrasions thoroughly and hope they don't get infected" is the step no one describes. Wounds are, not surprisingly, common, and some people, like world record holder Reg Mellor, wear white pants to show off the blood strains. Mr. Mellor's world record? 5 hours and 26 minutes.
Interest in ferret legging is dwindling, which is probably a good thing for both ferrets and competitors. There's no mention about whether there are any ferret legging family dynasties, but I suspect that regularly shoving sharp-toothed ferrets down your pants severely limits one's chances of reproducing. That's also good for ferrets and humans alike.
An attempt to be inclusive and create a women's competition involving sticking ferrets up a blouse apparently failed - likely due to relative differences in common sense amongst the genders.
I’ve written about lymphocytic choriomeningitis virus (LCMV) before, as an interesting but pretty uncommon rodent-associated disease. Human infections are mainly associated with handling rodents, although other routes of transmission, such as organ transplantation from an infected donor, have also been reported. Being a disease associated with rodents and considering how rodents are produced in North America (i.e. mass production in large breeding colonies, followed by transportation to large distributors and massive mixing of animals), LCMV is bound to be a recurring problem associated with the pet rodent trade.
An issue of the CDC's ominously titled Morbidity and Mortality Weekly Report describes the risk of infection with LCMV to people who work in rodent breeding facilities. It all started with the diagnosis of meningitis in a person who worked in a rodent breeding facility in Indiana. An astute doctor suspected LCMV and the diagnosis was confirmed. The breeding facility was a pretty large one, housing approximately 155 000 (!) mice and 14 000 rats. An investigation of facility personnel ensued and approximately 25% of employees had antibodies against the virus, indicating previous infection. A large percentage of the workers reported having had signs consistent with disease (e.g flu-like illness), indicating that they were likely infected and not just exposed.
Considerable effort was put into testing the animals. Of over 1000 animals tested, 21% of mice had detectable levels of the virus in their bodies. That’s pretty impressive and concerning, both for employees and anyone receiving animals from this facility.
In response to this investigation, all mice at the facility were euthanized, and the facility was thoroughly cleaned and disinfected.
This report highlights the risk of exposure to LCMV for people who work with rodents, especially in large facilities such as this. It also highlights the risks posed to people buying rodents from these facilities, which also includes other diseases in addition to LCMV. Good general hygiene and infection control practices should greatly reduce the risk of LCMV transmission to rodent owners. In particular, efforts should be directed at new rodents, since LCMV shedding is probably greatest during the initial period after an animal enters a household or other facility. Virus shedding it often transient, and once they get out of the high-risk facility and become acclimatized to their new home, shedding rates in these rodents probably decrease over a short period of time. Overall, the risk of LCMV in someone with a pet rodent is low, but these basic preventive practices are easy to do and make a lot of sense.
Photo: Female mouse with her litter. (Photo credit: Seweryn Olkowicz) (click image for source)
The annual US rabies surveillance report has been published in the latest edition of the Journal of the American Veterinary Medical Association (Blanton et al 2012). There's not really anything earth-shattering in it, but it's a good overview of the rabies diagnoses in the US from 2011. As always, it only provides a peek into rabies in wildlife (since only a small percentage of wildlife with rabies get diagnosed and reported) but numbers and trends in domestic animals, along with general wildlife data, provide useful information about the state of this virus in the US. Among the highlights:
- Rabies was diagnosed is 6031 animals and 6 people, from 49 states and Puerto Rico (Hawaii remains rabies-free). This is a 2% drop in animal cases from 2010, but I don't put much stock in that because the numbers are weighted towards wlidlife cases, and it's hard to have confidence in year-to-year numbers of rabid wild animals (because it's so dependent on what actually gets tested).
- The main wildlife species that are involved in maintaining the rabies virus in the US (reservoir species) continue to be raccoons, bats, skunks and foxes on the mainland, and mongooses in Puerto Rico. The relative importance of these species varies between regions.
- Raccoons were the most commonly affected species, accounting for 33% of all rabid animals reported. Other leading species were skunks (27%), bats (23%) and foxes (7%). Less common species included coyotes, bobcats, javelinas, deer, otters, mongooses, wolf hybrids, groundhogs and beavers.
- Cats were the leading domestic animal, with 303 diagnosed cases. Dogs came in next with 70, followed by cattle (65), horses (44), and goats and sheep (12). There were also single cases in a domestic bison and an alpaca.
- The six human cases represent the highest annual number of cases since 1994, if you exclude 2004 where four cases were associated with transplantation of organs from a single infected person. In a review of the 24 domestically-acquired human cases from 2002-2011, 88% were linked to bats.
- Three of the six 2011 human cases were acquired outside of the US; one each from Haiti, Afghanistan and Brazil - and all from dogs.
- Two of the three domestically-acquired cases were associated with bat contact. The source of the remaining case, an eight-year-old girl, is unknown, but contact with cats from a feral colony near the girl's school is a possibility.
- 5/6 people with rabies died. That's actually an impressive survival rate, since any survival is still a very noteworthy event when it comes to rabies. The survivor was the eight-year-old girl, and she apparently has suffered no longterm cognitive impairment.
Interestingly, we get a good synopsis of Canadian rabies data in this report too:
- 115 rabid animals were identified, with 92% being wild animals.
- There were three rabid livestock (two of which were horses) and six dogs and cats.
- No rabid raccoons were identified, continuing a trend started in 2009.
And regarding rabies in Mexico:
- 148 rabid animals were identified, mainly cattle (82%).
- Rabies was diagnosed in 20 dogs, with evidence that the canine rabies virus variant (which has been eliminated from Canada and the US) is circulating in some regions.
- There were three humans cases: two acquired from vampire bats and one from a skunk.
When I give talks about pet therapy animals, I talk about appropriate and inappropriate animals. On one slide I have a picture of a hedgehog, and I use it as an example of an animal that sometimes makes its way into pet therapy programs, despite standard guidelines to the contrary. This is a species that raises significant infectious disease concerns because hedgehogs can carry an impressive array of microorganisms that can be spread to humans. A big one is Salmonella.
So, it doesn't come as too much of a surprise that the CDC is reporting a multistate outbreak of salmonellosis associated with hedgehogs. Here are the highlights:
- Fourteen infections have been reported between December 2011 and August 2012. There are probably many more because in most outbreaks, only a minority of affected people get tested.
- People have been infected in six states (Alabama, Indiana, Michigan, Minnesota, Ohio and Washington), all with the same strain of Salmonella Typhimurium.
- All 10 people that were interviewed reported contact with hedgehogs or their environments. Considering the rarity of hedgehogs as pets, that's a pretty good indicator that hedgehogs were the source. The outbreak strain of Salmonella was detected in two households, in areas where the hedgehogs lived or were bathed.
- No one has died, but three people were hospitalized.
- As it typical, a large percentage (50%) of affected individuals were children 10 years of age or under.
The fact that this outbreak appears to have occurred over a long period of time and a large geographic area strongly suggests that this might be ultimately traced back to a common breeder or intermediary source. Many small pets like these are mass produced by large breeders and shipped across the country, creating the potential for a problem at a single breeder to have far-reaching consequences in other breeder colonies and in households. This has been shown repeatedly with species like hamsters and mice.
This report doesn't mean that hedgehogs shouldn't be kept as pets. However, hedgehogs do seem to be a higher-risk species than average, and households that include high-risk individuals (e.g. young children, elderly persons, immunocompromised individuals, pregnant women) should probably avoid them. More importantly, the potential for transmission of Salmonella and other pathogens indicates the need for good basic, routine hygiene practices, such as washing hands after handling a hedgehog, keeping them out of the kitchen, not bathing them in kitchen or bathroom sinks, and supervising contact between hedgehogs and kids.
As with most "pocket pets," guinea pigs don’t get a lot of attention in the scientific literature. As a result, we are limited in what we know about certain diseases in this species, and we tend to rely a lot on personal experience, small case studies and extrapolation from other species. It’s not that these sources of information are bad, they’re just not a replacement for larger, more controlled studies.
A recent study in the journal Mycoses (Kraemer et al. 2012) provides a rather comprehensive overview of ringworm (dermatophytosis) in these little fuzzy critters. The authors surveyed 74 owners of guinea pigs with ringworm and veterinarians. Here are some highlights from the results:
- 97% of ringworm infections were caused by Trichophyton mentagrophytes. Ringworm can be caused by a few different species of fungi, with a different organism, Microsporum canis, being most common in dogs and cats.
- 43% of the time, a new guinea pig was introduced into the household in the weeks preceding the onset of disease, and around one-third of affected guinea pigs had been in the household for less than 3 months. That’s not too surprising, since new animals are often a prime source of infectious diseases. It shows the importance of ensuring that new pets are examined carefully and are healthy before they are brought into the household. It’s certainly no guarantee that there won’t be problems, since healthy-appearing animals can be shedding various infectious agents, but it helps reduce the risk.
- Ringworm lesions were most common around the head. Hair loss was the most common sign, with scaling and crusting also common.
- Signs of ringworm were also present in other guinea pigs in the household in over one-third of cases.
- Various treatments were used and some animals weren’t specifically treated. In fact, 7/8 of the guinea pigs that did not receive specific anti-fungal therapy got better. It's known that ringworm can be self-limiting (meaning the animal will get better on its own over time). However, treatment can speed the process up and decrease the likelihood of transmission to other animals or people.
- In 24% of cases, people in the household also had signs of ringworm, on the head, neck and arms. Children were most commonly involved. That’s not too surprising since kids probably had more contact and closer contact with the animals than their parents.
While not a severe disease, ringworm is a problem because it’s highly transmissible. It can easily and quickly spread between animals, and between animals and people, and elimination of ringworm from a highly contamination household can be a major hassle. Presumably the risk of widespread environmental contamination is less with guinea pigs compared to dogs and cats because of their smaller size and tendency to be kept confined to cages most of the time.
Ringworm should be considered in any guinea pig that develops hair loss or other skin/hair problems. This is particularly true if it’s a new acquisition or if a new guinea pig has been introduced to the household recently.
If ringworm is suspected, a prompt visit to the veterinarian is in order. The guinea pig should be handled sparingly (or ideally, not at all) until the cause of the skin disease is identified. Close attention should be paid to hand hygiene, and even the use of gloves could be considered, although gloves aren’t a cure-all and people sometimes misuse gloves to such an extent that they actually increase the risk of spreading disease.
If a new guinea pig is obtained, it’s ideal to have it examined by a veterinarian before it comes into the household. I’m a realist and realize this is unlikely, but it’s ideal. In lieu of that, it’s important to get a guinea pig from a reputable source, to ensure that other guinea pigs from the same source don’t have skin disease, and to carefully examine the animal for skin lesions before it gets home. It’s also ideal to keep any new guinea pig in its own cage for a couple weeks to act as a quarantine period and allow for identification of any incubating diseases.
If owners of an infected guinea pig develop skin lesions, they should be examined by their physician, and make sure the physician knows they have been in contact with an infected animal.
The CDC is investigating CDC is investigating more cases of salmonellosis associated with feeder rodent contact, caused by the less-than-catchy-named Salmonella I 4,,12:i:-. This strain is the same one that was implicated in a large and prolonged outbreak in the US and UK in 2009-2010 which was also associated with frozen feeder rodents (rodents sold frozen as reptile food) from a single US supplier. The current outbreak has affected people in 22 US states from August 2011-February 2012, and involvement of the same strain from the same source certainly leads to suspicion that this is actually an ongoing problem.
In the latest outbreak:
- 46 people have become sick. As is common, kids have borne the brunt of this outbreak, with the median age of affected persons being 11 years.
- 37% of affected people were kids five years of age or younger. Since this outbreak involved feeder rodents, clearly people aren’t heeding the guidelines that kids of that age shouldn’t be in households with reptiles.
- No two affected people reported buying rodents from the same store. This shows how widespread the problem is and that it must be originating from the place where the rodents are bred and/or distributed, not a focal pet store issue.
Record-keeping at the pet stores complicated figuring out the source. However, two breeders that supplied pet stores received mice from the company that was the source of the 2009-2010 outbreak. This suggests that not only were people exposed from frozen feeder rodents in the earlier outbreak, but that breeding colonies in different areas were infected from that source. This may have allowed wide dissemination of this Salmonella strain into numerous rodent breeding colonies, creating many possible sources of exposure for members of the public purchasing feeder rodents. The large-scale commercial nature of rodent breeding and wide distribution network creates a great opportunity for widespread outbreaks, as is apparent here and with various other outbreaks (including salmonellosis outbreaks from guinea pigs and baby poultry).
If you are going to buy feeder rodents:
- Treat them as if they are carrying Salmonella, because they just might be.
- Keep them away from human food. Keep them in a separate freezer or fridge, or in a sealed container if they have to be in the same fridge as human food.
- Don't handle them in the kitchen.
- Wash your hands thoroughly after handling.
- Keep them away from young children, as well as people with compromised immune systems, elderly individuals and pregnant women. None of these groups should have contact with reptiles either.
Image: A package of frozen rats, as sold commercially for feeding reptiles.
Guinea pigs are relatively benign pets in terms of zoonotic diseases, but like any animal, they can carry some pathogens that are transmissible to people. This was highlighted in a poster presentation at the recent International Conference on Emerging Infectious Diseases in Atlanta. The poster (Bartholomew et al) described a CDC investigation into an outbreak of Salmonella Enteritidis infections in people in multiple states in 2010.
Here are some highlights:
- The first affected person was a child who purchased a guinea pig from a pet store. The animal looked "frail" and was housed with the child's existing guinea pig. Later that month, both guinea pigs developed diarrhea and died. Shortly thereafter, the child developed diarrhea, fever, cough, chest and back pain, a rash and some other signs. Ultimately, a Salmonella infection of the sternum was diagnosed, indicating that Salmonella had traveled from the intestinal tract to the child's bloodstream and set up an infection in the breast bone.
- The CDC investigation focused on other people who had been diagnosed with the same strain of S. Enteritidis. They identified 10 such cases who also reported guinea pig exposure, scattered over 8 US states.
- The same Salmonella strain was also identified in guinea pigs, including one from a Texas guinea pig broker, around the same time as these cases were occurring.
- Most of the affected individuals were children. Three had purchased guinea pigs from the same pet store chain as the first child. Three other affected people were employees of stores from that pet store chain.
- Testing of the environment in pet stores from that chain did not identify Salmonella. However, since sampling was done well after people got infected, it doesn't mean it wasn't there earlier.
- No common guinea pig source supplier was found, but one Pennsylvania breeder was identified as a possible source for the cases associated with that pet store chain.
This is pretty strong evidence that the infections were guinea pig-associated.
Some take-home messages:
- Any animal can be a source of potential infection, and general hygiene practices should be used all the time to reduce exposure to pet feces.
- Sick animals might mean the potential for sick people. While it's sometimes tough to convince people that testing dead animals (especially dead animals that don't cost much) is useful, it might have had a great impact on the care of the first child. If physicians knew that the child was exposed to Salmonella, they might have been able to make the diagnosis much quicker.
- Pet stores are not uncommonly implicated as sources of outbreaks, and there are also risks to their staff. Pet stores need to have good infection control, hygiene and disease reporting practices.
- The nature of pet rodent distribution, with large breeders sending animals to brokers where large numbers of animals get mixed and sent on to pet stores, creates the potential for widespread disease transmission, as has been repeatedly shown in the past.
Rat bite fever is an infection caused by the bacterium Streptobacillus moniliformis (the main cause in most countries) or Spirillum minus (the main cause in Asia). The condition is, not surprisingly, associated with being bitten by a rat, although it can be transmitted by other routes such as dog bites. The bacteria live in the mouths of most rats (and a less-well-understood percentage of other animals). Disease occurs when these bacteria make it into the body via a bite, or other high-risk contact such as kissing the animal or letting it lick an open wound.
The Australian case report describes a 26-year-old woman who had a fever and sore throat, which progressed to a severe unrelenting headache with nausea, vomiting, sensitivity to light, neck stiffness and pneumonia. Streptobacillus moniliformis was isolated from a blood sample. The strain was fortunately susceptible to the antibiotics that had been started earlier. It wasn't until a couple of days later that a rash (a classic sign of rat bite fever) developed. Fortunately at that point the diagnosis had already been made and the woman was responding to treatment.
After "further history taking" it was revealed that the patient owned two rats and, while she had not been bitten, she had close contact with them, including kissing. It's not clear when the "further history taking" occurred, but it probably happened after they found the S. moniliformis and made diagnosis, which rounds out the case report nicely but doesn't speed up the diagnosis or improve case care. The animal contact question needs to be asked at the start. One of the Lessons from Practice that the article highlights is "A thorough history, including history of animal exposure and pet ownership, should be taken for all febrile patients." Remove "febrile" and I agree completely.
Anyway, the woman responded to treatment and went home after 17 days in hospital. Most people that are properly diagnosed and treated survive, but rat bite fever can be fatal.
Most rats carry at least one of the two bacteria that cause this disease. There's no indication to test pet rats (since we assume they all have the bug until proven otherwise, and we can't confidently prove otherwise) or treat them (since we have no evidence we can eliminate the bug from the mouth of a healthy rat). It's a limited but ever-present risk of rat ownership, and one that can be greatly reduce by avoiding kissing rats, preventing bites, proper wound care should bites occur, and ensuring that physicians know about potential rat contact if illness develops.
A Kitchener, Ontario family is dealing with a household outbreak of ringworm, likely contracted from a new pet guinea pig. Ringworm is a fungal infection cause by a few different types of fungi. Some ringworm fungi are able to infect both people and animals, and those can be spread in households from direct contact with an infected person or pet. In this case, the Gross family purchased a new guinea pig from a local pet store, and unfortunately, ended up bringing ringworm home as a bonus.
As is common, the new pet was the centre of attention when it got home, and the Gross' three children, ages 8, 5, and 2, had very close and frequent contact with it. The next day, the family noticed an area of hair loss on the guinea pig, at which point they took it back to the store. Ringworm was subsequently diagnosed, though there's no mention of how this was done, nor is there any mention of what actually happened to the little critter afterward.
The big problems started a week later, when a red lesion was seen on their youngest child's back. This was also diagnosed as ringworm, though again there's no mention of how, or whether it was definitively confirmed as ringworm. The newspaper report goes on to say "More spots kept appearing on Matthew’s skin as Gross was given different steroid creams to try and contain the infection." You always need to take media descriptions of medical issues with a grain of salt. Hopefully, the child was treated with anti-fungal cream, not steroid cream, as the latter not only won't treat ringworm, they may make it worse if used alone. Steroid creams are often prescribed for non-specific skin issues (particularly if the skin is very itchy, which can certainly happen with ringworm), but in a case like this where there was known contact with an animal with ringworm, I have to hope that the physician was treating with an antifungal cream instead of, or in addition to, a steroid cream.
Anyway, whether despite or because of the treatment, more skin lesions kept appearing on the child. Then skin lesions were found on the family dog, and both the dog and cat ended up being treated for ringworm. The treatment for dogs and cats is relatively straightforward, but it's still a hassle and can be somewhat expensive, and often takes several weeks.
The family has contacted the pet store about paying for cleaning supplies, air purifiers and veterinary bills, but the company did not respond to the newspaper reporter's inquiries, citing an ongoing investigation. It's hard to say whether the company should be held responsible. It largely depends on the measures they take to reduce the risk that they are selling pets at increased risk of transmitting infectious diseases. There's always a chance of picking up something from a pet, so an infection does not necessarily indicate incompetence or liability. If a store had reasonable practices in place, it's probably the purchaser's responsibility to take proper precautions when they take the pet home, and it's an example of why prompt veterinary examination of new pets is always a good idea. It's rarely done, particularly for species that cost less than the price of a veterinary exam, and you never know whether it would have helped prevent anything in this case, but in many instances it can help identify potential issues and address them before problems occur.
Preventing outbreaks like this can be difficult. Ringworm can be found on animals in the absence of any skin disease, so you can't always tell an animal is infected by looking at it. (However, in this case if a large patch of hair loss was noticed by the owners the day after the guinea pig came home, it's likely that something was evident the day before). Ringworm is spread by direct contact, which is common between pets and kids, especially new pets that often get smothered with attention in the first few days. Good hygiene practices, particularly attention to handwashing, can certainly help, but some degree of risk will remain.
Overall, guinea pigs are relatively low risk for zoonotic diseases, but this report shows that even "low risk" pets can be sources of infection. Fortunately, while controlling ringworm outbreaks can take time and be frustrating, it's not a serious disease and it is controllable.
More information about ringworm can be found on the Worms & Germs Resources page.
Having pets in school classrooms is a somewhat controversial subject. For every good point that's raised (e.g. promoting empathy, entertainment, learning about animals and their care) there are bad points (e.g. poor environment for the pet, rough handing, disorganized or absent medical care, disease transmission, fear, allergies, distraction). Some organizations have developed detailed guidelines for using animals in classrooms, but animals are often in classrooms with little consideration of the issues. Little is known about what happens with these pets. We tried to do a survey of teachers from some school boards a few years ago and only ended up getting about two responses out of hundreds of eligible teacher participants (the overall lack of support from board administration didn't really help get the survey out and get teachers interested either, but that's another story). So, we really don't have a good idea of the types of animal contact that occur in classrooms or the problems that result, but we know from various case reports that complications like infections can and do occur.
PetSmart and the Pet Care Trust have a "Pets in the Classroom" program where kindergarten to grade six teachers can get support for having a pet in the classroom. Their release outlines a few of their perceived benefits, and some of the complexities of having pets in classrooms. Their points are in italics, with some comments from me.
Hamsters make fun classroom pets because they are active and teach children the importance of schedules and responsibilities.
- Yes and no. They can be entertaining, but they can also be distracting. You have to differentiate something that's a novelty from something that is being used as part of the educational curriculum. Hamsters can be injured with rough handling by young children and close supervision is required. They may also bite when handled, especially when handled by young kids who don't know what they are doing. Plans to take care of the hamster over holidays and the summer are needed, and are often not considered in advance. The disease risks of hamsters are relatively low, but not non-existent. Having nocturnal animals in a busy daytime setting is also questionable ethically.
Guinea Pigs are easily handled and encourage children to follow a regimented routine.
- They are similar to hamsters in their benefits and risk, but their larger size makes them more robust and less prone to handling injury. They are probably one of the better mammals to have in a classroom, but still require good organization, planning and practices.
Fish are a great way to illustrate basic chemistry and biology principles while students follow regularly scheduled water changes.
- Fish can be great classroom animals. There are ways to incorporate them into the curriculum, from behaviour to animal care to feeding to water quality and environmental concerns. They need some care, with regular feeding and proper water maintenance, but with basic supervision and planning, the risks to the animals and people are minimal and they can be of benefit educationally.
Bearded Dragons depend on their environment for heating and cooling and are a great way to teach about geography and the environment.
- Bearded dragons (see image) are great little reptiles with a lot of personality. However, they have specific requirements for care and feeding, something that cannot be easily fulfilled in a lot of classrooms. Also, being reptiles, they are high risk for Salmonella shedding. In a low risk household, it's not a big deal with basic hygiene practices. However, in a classroom with lots of kids, perhaps limited enforcement of hygiene, and kids eating in the area where the reptile is, the risks get higher. General guidelines are that children less than five years of age and people with compromised immune systems should not have contact with reptiles. This means they should not be in kindergarten classrooms or rooms where such students may spend time. More complicated is the issue of immunocompromised individuals. I'm not convinced that teachers always know when one of their students is immunocompromised, and what happens if there's an established pet and a student becomes immunocompromised? Bottom line: Reptiles shouldn't be in classrooms.
Leopard Geckos are docile in nature and teach children about different nocturnal behaviors.
- These are interesting little critters, but not good classroom pets, like other reptiles, for the reasons outlined above. Nocturnal pets may not be great for classrooms either since the daytime activity and disruption may be harmful to them in the long term.
Certain pets can be good additions to certain classrooms, with some logical planning and common sense, but poor planning and bad animal choices can be harmful to students and animals. School boards should be proactive and develop or adopt sound protocols for classroom pets.
The more we look, the more we find when it comes to MRSA (methicillin-resistant Staphylococcus aureus). As people start looking for it in different animal species, it's often found. We've found it in many species already, including dogs, cats, rabbits, pigs, walruses, dolphins and alpacas, so it's not a big surprise to see a recent paper in the Journal of Clinical Microbiology (Ferreira et al 2011) about suspected MRSA transmission between a human and a hamster.
The case report describes a person with advanced cystic fibrosis who had undergone a lung transplant and had various other medical problems. Prior to another surgical procedure, MRSA was identified through routine pre-operative screening. Nasal and rectal swabs were then collected from the person's three pet hamsters, one of which was positive. The MRSA isolates from the human and hamster were the same, supporting transmission from one to the other. Given the person's underlying health problems, frequent contact with the healthcare system, the typical human origin of the strain that was found, and limited contact of hamsters with other animals or people, it is most likely that MRSA was transmitted from human to hamster in this case.
The paper concludes with: "Should testing of the pets of MRSA-positive patients be recommended? At this point, we recommend that MRSA-positive patients be informed that their companion animals can be potential sources of infection or reinfection. In the presence of a MRSA-positive human or animal, heightened hygiene practices should be instituted and unnecessary close contact should be avoided. Screening of household pets might be indicated in situations of recurrent MRSA infections despite adequate treatment or when immunocompromised patients live in the household."
That's consistent with our standard recommendations and hits most of the key points:
- Awareness is critical. People need to know what the risks might be and what they can do about them so that they can make informed decisions and realize why recommendations are being made.
- Testing of pets is rarely useful, particularly in the absence of a recurrent MRSA problem.
- Good hygiene practices are critical.
I don't really agree with the comment that testing of pets might be indicated when immunocompromised people are in the household (although the comment is properly hedged by saying "might be indicated"). A large percentage of the population has some degree of immunocompromise, and there's a huge spectrum from minimal risk to tremendous risk. Even in high-risk patients, screening is questionably useful to me because it doesn't really change what I'd do.
- If I screened a hamster from a high-risk person and found MRSA, I'd say that it probably came from the person, that it's possible it could be transmitted back to the person, that good hygiene practices should be followed and close contact should be restricted. There's no indication (or ability, in reality) to treat the hamster.
- If the hamster was negative, I'd say it was possibly negative because screening is not 100%, that the hamster could be exposed to MRSA from the owner at any time, and so to manage unknown colonization and reduce human-hamster transmission, I'd recommend good hygiene practices and restriction of close contact.
- If I'm going to do the same thing with a positive and negative result, I don't do a test.
This paper should be yet another reminder that we live in a complex relationship with our pets, including microbiologically. While we need to consider the role of pets in human infection (and the role of humans in pet infection), and we need to balance that with the positive aspects of pet ownership in order to maximize the benefits while minimizing the costs.
Easter is one of those holidays when there are concerns about dumb pet purchases. Spur-of-the-moment purchases of inappropriate pets can lead to animal suffering and death, and risk of human infection. Easter's problems: baby chicks and rabbits.
Rabbits can make great pets. They're a long-term commitment, but they’re relatively low maintenance, a lot is known about how to raise them and they are generally low risk for transmission of infections to people. Chicks are a different story. Chicks are notorious Salmonella vectors and have been linked to numerous outbreaks. They are easily injured and often improperly raised. They also grow up (well, some of them do, at least) to be full sized poultry, something that most people don't really want.
A story from Vidalia, Georgia highlights some of the issues with Easter pets. In it, Tracy Gunn describes his need to buy a chick for his daughter - and not just any old chick, but a dyed chick, something that’s illegal in 36 US states, but not Georgia. Gunn states "I don't know what she's going to do with it." Sounds like a recipe for a few minutes of novelty, followed by a relatively short life for the chick. At least his daughter’s 17, and not in the high risk group for salmonellosis.
Alongside the cage full of multicoloured chicks was a collection of rabbits.
“The bunnies sell real good for Easter. We've been selling a lot of them about the last month. Can't keep enough of them.” said a store employee.
He followed that up with “They buy (rabbits) for their kids for Easter, then they take Easter pictures and stuff like that with them, I'm not sure about what happens to them afterward.”
That’s the problem. Kids get a few minutes of novelty enjoyment, but then a lot of those animals end up dead, released into the wild (not a good thing) or dropped off at an animal shelter, because people don't think about the "afterward" part before they buy.
Pet purchases need to be made with thought and foresight:
- Do I really want this pet?
- Am I committed to taking care of it for its entire life?
- Can I take care of it properly with my current living situation?
- Can I afford to take care of it properly?
- How do I take care of it?
- Are there any disease risks that I need to be concerned about?
- Are there any people in the household who are at high risk for disease caused by this type of animal?
If you can't answer these questions, don't buy or adopt an animal - of any kind.
A Montreal pediatrics resident has expressed concern about rat bite fever in kids. Dr. Karine Khatchadourian described three cases of this bacterial infection in a paper called "The rise of the rats: a growing paediatric issue," published last year in the journal Paediatrics and Child Health. The article didn't really present any evidence that this is a "growing" issue, but it is a disease of concern.
Rat bite fever is a bacterial infection most commonly (but not exclusively) associated with bites from rats. Healthy rats often carry the bacterium that causes the disease (Streptobacillis moniliformis in North America), and infection can occur when the bacterium is inoculated into the body by a bite, or when it's spread to mucous membranes like the mouth through direct mouth-mouth contact with pet rats (yes, some people kiss their rats).
The disease can be serious, and even fatal, if not properly diagnosed and treated. It's also a classic example of why physicians need to ask their patients about pet contact and why people need to take bites from pets seriously. Knowing that a rat is in the house, and particularly if a bite has occurred, is a key factor in helping make the diagnosis. If the physician doesn't ask the question, this critical piece of information may be missed, along with the diagnosis.
Being concerned about rat bite fever (and other zoonoses) is good, and ways to educate pet owners and physicians about such diseases are needed. However, extrapolating "rat bite fever is bad" to "rats are bad" is a stretch. The statement in the paper "Should we, as health care professionals, advocate to have rats banned from being sold in pets stores?" is over the top.
Every animal carries many microorganisms that can cause disease in people, given the right circumstances. Similarly, every person you meet is carrying something infectious. The key things to consider are:
- What is the likelihood of infection?
- How severe is the disease that may occur?
- What can be done to reduce the risk of infection?
- What is the cost-benefit, i.e. how do the potential risks compare to the potential benefits?
How can the risks be reduced?
- Rat owners need to be aware of the disease.
- Good handling practices are needed to reduce the risk of bites.
- Any bites that occur should be promptly cleaned and a physician contacted if there are concerns.
- Contact of rat saliva with broken skin or mucous membranes (e.g. kissing the rat) should be avoided.
- Physicians need to know whether their patients own pets, including rats, and know what diseases may be associated with those types of animals.
With this type of approach, the risk of infection can be reduced and the ability to properly and promptly diagnose the disease, in the odd case that it occurs, can be maximized.
I don't want to downplay rat bite fever. It certainly can cause illness, particularly in children under the age of 12. A recent paper reported a fatal case in a 14-month-old boy, however in that case the infection was associated with ferrets, not a rat.
Parents of small children need to think about the risks of zoonotic diseases, as well as injuries (e.g. bites) when deciding whether to get a pet, and what type of pet to get. If people like rats, take care of them properly and communicate well with their physician (and if their physician is aware of the issues), then the risks of serious disease are quite low.
Dr. Khatchadourian suggests that parents "should stick to cats and dogs, and steer clear of rats." However, that's no assurance that a zoonotic infection will not occur. There's no evidence indicating the risk of disease is less with those species. It doesn't even eliminate the risk of rat bite fever, since Streptobacillus moniliformis can be found in the mouths of dogs too.
Rather than banning rats from pet stores, we should focus on educating pet owners, veterinarians and physicians about zoonotic diseases.
A recent press release from The Pet Care Trust reported on the status of its Pets in the Classroom program, which provides support to teachers to have pets in school classrooms. On the surface, it seems like a fine concept, helping to enrich school activities. However, it's one of those ideas that can do a lot of good, or it can also be very bad, depending on how the program is run.The Pet Care Trust has some useful information about pets in classrooms, and anyone considering having a pet in a classroom needs to be aware of a variety of concerns, including:
- Welfare of the pets (e.g. minimizing stress, preventing abuse)
- Adequacy of pet care, particularly during weekends and holidays
- Access to and cost of veterinary care
- Distraction of students
- Infectious disease transmission
Given the topic of this blog, I'll focus on the last one.
Infectious disease transmission from pets in classrooms is a real problem. Zoonotic infections can and do occur in these situations. The risks are quite variable, and depending on the animal, children, classroom and pet care, can range from inconsequential to quite serious.
The type of animal is very important. Certain species are very high risk for carrying particular infectious diseases and for transmitting them to people. Reptiles are notorious for Salmonella, so it is recommended that children under five years of age and immunocompromised individuals (among others) not have contact with reptiles. Even with older kids there's a risk, and older kids have picked up Salmonella in classrooms from reptiles or a reptile's food (e.g. frozen rodents).
So, it's concerning that 435 of the 2066 grants handed out by this program were for reptiles, and included kindergarten to Grade 6 classrooms. A lot of reptiles went into classrooms with a lot of young kids. Typically, elementary school children (at least around here) eat in their classrooms, which raises even more concern. While the majority of students would be five years of age or older, immunocompromised kids are not exactly uncommon, and it's unclear whether teachers have adequate knowledge of whether kids in their classes are immunocompromised, nor whether they understand that such children are at increased risk of disease from classroom pets.
I'm not saying pets in classrooms are a bad idea. However, it's often done poorly and with little forethought. To be effective and safe, you need to consider many things, such as:
- What species should it be? From my standpoint, no reptiles or other high-risk species (e.g. baby chicks) should be in any classroom, because you can't guarantee a high-risk person won't be around. The animal needs to be small enough to be properly housed in a classroom. Its care requirements need to be basic and readily met. It shouldn't be a species that gets stressed easily, and it needs to be an animal that can tolerate all the activities that go on around it (e.g. a nocturnal species is probably not a good idea).
- What types of hygiene/infection control practices need to be used around the animal and how will they be enforced?
- What disease or injury (e.g. bite) risks are present and how will they be managed?
- Who will take care of it? This means who will take care of it for its lifespan, not just the upcoming school year.
- Who will arrange and pay for any medical expenses that arise, either for preventive medicine or treatment of disease?
- Will parents be notified?
- What happens if a child in the class is allergic to or afraid of the animal?
- Will proper supervision be available at all times?
- Who from the school or school board must give permission, and is there a standard approval process? (There should be, but there rarely is.)
- Why is the animal going to be there? Will there be any educational use or it is just there for fun/decoration?
If you can answer all these questions adequately, then a pet might be a good fit in the classroom in question. If you can't answer them, or can't be bothered to try to answer them, then there should be no pets in the classroom until you can.
Cowpox virus is an example of a virus with a misleading name. It's place in history is from Jenner's observation that milkmaids who had been infected with cowpox were resistant to smallpox, leading to the use of cowpox (which causes very mild disease) to protect against smallpox (which is very, very bad). While cattle can be infected, they are not the true host of this virus, and infections in cattle are actually quite rare.
Various rodents are the true reservoir of cowpox. Other species can be infected from contact with infected rodents, including people and pets. Among pets, cats are most commonly infected, with most reports coming from central Europe. Cats may be infected more often because they may more often have close encounters with rats, but they are probably also inherently more susceptible to the disease than dogs.
Cowpox infections in dogs are very rare, but a case was recently described in Veterinary Dermatology (von Bomhard et al 2011). It involved a five-month-old Rottweiller from Germany that developed a very mild case of cowpox, with a single nodule on its muzzle. The dog recovered uneventfully, but it was an interesting case of a rare disease in a dog, and one that has some human health considerations.
People can be infected with cowpox from pets. In particular, infections from pet rats have been a problem in central Europe over the past few years. Outbreaks of human infections have been identified associated with widespread dissemination of infected rats from infected breeding or distribution facilities. Infections have also been reported from cats, and cats are a significant concern because of their ability to be a bridge between wild rodents and people, and because of the close contact they tend to have with people.
It's not surprising that disease was so mild in this Rottweiller puppy, and the risk to people in contact with the dog was probably limited because of the mild nature of the infection. No human cases were reported associated with this dog. Human infections from dogs have not been reported, largely because the disease is so rare in dogs and perhaps because when they are infected, dogs tend to have very mild disease. Cowpox is of minimal concern for most pet owners, but it something to be aware of when obtaining a new rodent, especially in regions where cowpox is an issue, and when dealing with cats in areas where cowpox is endemic in wild rodents. Some basic preventive measures include:
- Pet rodents and cats (especially newly obtained rodents) that develop skin lesions should be handled with care and be examined promptly by a veterinarian.
- Wild rodents should never be caught and kept as pets (for various other reasons, as well).
- Contact between domestic pets (particularly pet rodents and cats) and wild rodents should be prevented.
One concern with uncommon pets is our relatively poor understanding of the infectious agents they may carry. For our "established" pet species, we have a reasonable understanding of what bugs tend to be present and which animals may be at higher risk. The less common the pet, the less research tends to be available, making it harder to assess risks and determine what types of prevention programs need to be in place.
A recent study published in Veterinary Parasitology (Levecke et al. 2010) provides information about chinchillas and the parasite Giardia. This Belgian study involved collection of stool samples from 80 healthy pet chinchillas from 4 households and 4 breeders. They identified Giardia in a rather astounding 66% of samples. Young animals were more likely to be infected, as were animals that participated in shows (I didn't realize there were chinchilla shows).
A subset of samples were typed using molecular techniques to determine the Assemblage (strain/type) of the Giardia. This is very important from a human health standpoint, because some types of Giardia can infect both animals and humans, while others are more host-specific. Most samples (86%) contained Assemblage B. However, a combination of different Assemblages was common, and Assemblages C (71%), A (52%) and E (9.5%) were also found. Importantly, all positive samples contained at least one of Assemblages A or B, which are types that can cause disease in people. Assemblage C is typically associated with dogs and Assemblage E with livestock, so those results were a little surprising.
What does this tell us? It tells us that a large percentage of healthy chinchillas may be shedding Giardia in their stool, and that they typically shed types that can cause disease in people.
Does this mean people are getting sick from pet chinchillas? Not necessarily, but it indicates there is a risk.
What can chinchilla owners do? It's pretty straightforward. Giardia has to go from the animal's stool to a person's mouth to cause infection. The use of good general management and hygiene practices (especially handwashing) should greatly reduce the risks. As the folks at Barfblog say, "don't eat poop."
Should chinchillas be tested for Giardia? Probably not. A single negative result does not necessarily mean Giardia isn't there or that it never will be. Given the numbers reported here, it's best to go on the assumption that every chinchilla is (or could be) positive, and take appropriate precautions.
Never a dull moment...
This morning the Toronto Star published an article about the intended euthanasia of 350 animals at a humane society in Newmarket due to an ongoing ringworm outbreak. This was quickly followed by another article about the same event that gave a few more details, including some comments from the OSPCA chief executive officer Kate MacDonald, who confirmed that the euthanasias had begun. A "very aggressive strain" of ringworm and "human error" (related to a breakdown in protocols) are currently being blamed for this morning's actions. A lot of people are (understandably) very upset. No one ever wants to see an infectious disease outbreak come to something like this.
I’m hesitant to comment too much at this stage, because we still don’t have all the facts - apparently even the duration of the outbreak is unknown. No one has said if all 350 animals are infected (or what percentage of them are), nor how many other animals are present at the shelter. We also don’t know what’s already been tried in terms of controlling the outbreak.
A few facts about ringworm (dermatophytosis) that people need to remember:
- Ringworm is a skin infection that can be caused by several species of fungi. It is not a "worm" at all. It is also very easily transmitted by direct or indirect contact with infected animals - their fur, their cages, their blankets, or anything else that may be contaminated with infected skin cells or hair. Such infectious material can even be spread over short distances (e.g. room to room) in dust that is stirred up into the air.
- Ringworm is transmissible to people, so with a large outbreak there are also issues with staff safety, and concerns with adopting out infected animals. For most people ringworm infection may cause itchy, uncomfortable skin lesions, but for higher-risk people (e.g. very young children, the elderly or immunosuppressed individuals) the infection can be much more serious.
- There are also a lot of animals (particularly cats) that carry ringworm without showing any signs of infection. If the Newmarket shelter has 350 animals with clinical signs of ringworm (a detail about which we have no information right now), that’s pretty bad, but even the animals who don't appear to be infected may be carrying the fungus and could spread it to others.
- Crowding, close contact and warm, humid environments are all factors that increase the risk of ringworm transmission. These are also all factors that are very hard to control in a crowded animal shelter.
- Ringworm is treatable, but it is not cheap or easy. Animals typically require systemic therapy (usually oral medication, which can be very expensive particularly in large dogs) as well as whole-body topical therapy (e.g. dips, shampoos, sprays), and they need to be treated for several weeks. Decontamination of the environment at the same time is critical to prevent reinfection.
Cleaning up a ringworm outbreak at a shelter with at least 350 animals is no small undertaking. The second article in the Star also describes personnel at the shelter this morning wearing "white hazardous material suits, latex gloves and plastic covers over their shoes", which would be considered reasonable precautions for entering a highly contaminated environment.
I'm sure we'll hear more about this in the days to come, and hopefully that will include more details about why the mass euthanasia was deemed necessary by the OSPCA.
Photo source: yorkregion.ontariospca.ca via www.thestar.com
A Phoenix, Arizona man is suing a pet store after he contracted rat bite fever from a rat he had purchased. It's not surprising to see a lawsuit following a serious illness, considering people in the US often try to sue for just about anything, but I'm not sure it won't get very far. I don't doubt that the man had rat bite fever, or that he got it from the rat he purchased - the question is, is the pet store really liable? Specifically, did they do anything inappropriate?
"Rats being sold to people should not have rat-bite fever," Heitzman's lawyer, M.E. "Buddy" Rake Jr., tells New Times.
Actually, the rats don't have rat bite fever... rats are healthy carriers of the bacteria that cause rat bite fever. There are two different bacteria that can cause the disease, Streptobacillus moniliformis and Spirillum minus. Streptobacillus moniliformis is presumably the cause here since it's the main cause of rat bite fever in the US. This bacterium is very commonly found in healthy rats, with upwards of 100% of healthy rats being carriers. You have to assume that every rat is carrying this bacterium.
"It wouldn't be any different if they sold someone a dog with rabies," he says. "I'm not in the nuisance-lawsuit business - he was in rough shape."
It would certainly be a different story if the store sold someone a dog that had signs of rabies. It's possible that someone could buy a dog that had been exposed to rabies but which was healthy at the time of sale, but that's pretty unlikely. However, a big difference is that there is a highly effective vaccine against rabies. There is no such thing for rat bite fever. If a pet store sells an unvaccinated dog of unknown origin that could have been exposed, despite knowing the need for rabies vaccination, there certainly could be liability issues. Selling a rat that is carrying a bacterium that we assume most or all rats carry anyway is different.
PetCo did not immediately return telephone calls this afternoon, but in its defense, there is an information pamphlet explaining exactly how to avoid contracting rat-bite fever available on the company's Web site. ...though it seems the pamphlet's best suggestion is to not get bitten in the first place.
It would be better if everyone who bought a rat was given the information sheet, but it's a start. The fact is, the best way to avoid rat bite fever IS to avoid getting bitten by a rat! Proper rat handling is a very important aspect of disease prevention, since you can never rule out the possibility that a rat is a carrier.
Our suggestion: Don't have a disgusting rat for a pet.
Whoa. Rats can make excellent pets. They can also carry infectious diseases. However, EVERY animal can carry infectious diseases, and rats are probably no more risky than most other domestic pets. The key is to take common sense precautions to reduce the risk of injury and infection (though the risk can never be completely eliminated). For rats, this includes selection of a rat that is not aggressive or fearful, knowing how to properly take care of a rat, knowing how to take care of a bite should it happen and being aware of some diseases for which you might be at increased risk because you own a rat.
Image source: http://commons.wikimedia.org
Urine from healthy animals is typically considered to be of little to no risk to people. This is generally true, at least for the otherwise healthy human population, but like with most things in infectious diseases, there are exceptions. An interesting one in rabbits is a bug called Encephalitozoon cuniculi. This microorganism (now classified as a fungus, but previously considered a protozoal parasite) is very common in healthy pet rabbits. In fact, the majority of rabbits have antibodies against E. cuniculi and may have it living in their bodies, particularly in the kidneys. It can cause infection of the brain, and is an important cause of neurological disease in rabbits, but more often than not it lives within the rabbit without causing any problems. Rabbits can shed spores of this organism is their urine, although they mainly do this only in the first few weeks after they've become infected, and shedding after that may be intermittent.
E. cuniculi is one of a group of microorganisms that became much more important when the HIV/AIDS epidemic hit. While rarely a cause of disease in people in the pre-HIV era, E. cuniculi is recognized as a potential cause of infection in people with compromised immune systems, particularly people with AIDS. Infections of people with normal immune systems are extremely rare.
It's always a challenge deciding what to do with a microorganism that can be shed by a large number of healthy animals. One reference "strongly advises" routine testing of rabbits, but that makes no sense to me. Here's why:
- Screening always comes down to a question of what you would do with the results. If you get a positive antibody test, it means that the rabbit has been exposed sometime in its life, but that does not mean that it is necessarily still infected or shedding spores - so it's not really convincing.
- Tests can be done to detect spore shedding but they are not particularly reliable. Since infected animals shed spores intermittently, a negative result here isn't convincing either.
- If the animal is positive, what would you do? If the household has no immunocompromised people, I'd say do what you've always done, and pay attention to good hygiene.
- If the animal was "negative," I'd say do what you've always done, and pay attention to good hygiene... same as for a positive rabbit.
- If there is an immunocompromised person in the house, I wouldn't say to get rid of the pet, since there's no evidence that's necessary. There is also no evidence that treatment is useful to eliminate E. cuniculi shedding rabbits. If the animal is positive, immunocompromised persons should avoid contact with urine and feces, and use good personal hygiene... just as they should do if the rabbit is negative!
.A public health expert has recommended that an exotic animal dealer's facility be demolished or "completely gutted and sterilized" because it is so contaminated with animal feces and vomit, as well as roach infested and swarming with uncaged animals. No evidence of infection control was present in the facility that "reeked of death and decay on a mammoth and overwhelming scale."
26 000 (yes, twenty-six thousand) reptiles, rodents and mammals were removed from US Global Exotic's Texas facility last week, in a raid prompted by an undercover investigation by PETA. An employee working undercover in the facility for PETA documented various abuses. The company now stands accused by the city of inhumanely housing the animals as well as denying them proper food, water and medical care. Hundreds of dead animals were found, and some animals had started eating one another to survive. An SPCA spokesperson said she stopped counting at 200 dead iguanas.
Buying certain things on the internet is fine. Buying live animals over the internet is something that you shouldn't even consider. This is a multi-million dollar industry that feeds off the naivety of people, the willingness of people to ignore serious welfare issues in their desire to get a unique pet, and the suffering of animals. Exotic pets can be good pets in certain situations, but tremendous numbers of them suffer and die from inadequate care at distributors, pet stores and homes, with many (many) more dying during smuggling.
If you want an exotic pet:
- Read a lot about it first. Make sure you can properly manage the animal and that it's legal in your area.
- Learn about any infectious disease risks and whether it's appropriate for your household. In general, exotic pets should not be present in households with children under five years of age, pregnant women, elderly individuals and people with compromised immune systems.
- Find a small, local breeder. Buy the animal from a place where you can see how they are raised so you can have more confidence they are healthy and have been properly cared for.
- If you want to buy an exotic pet from a pet shop, ask clear questions about the origin of the animal and request supporting documentation. Only buy a pet that was bred locally. US Global Exotics apparently sold most of their animals through pet stores.
Don't support illegal and unethical activities by buying exotic pets - if you really want to have such a pet, remember that it requires a lot of forethought and investigation of the source.
It seems like whenever a hit TV show or movie features an animal, there's concern about the "101 Dalmatians effect," whereby there's a mad rush to get the animal for a pet. When 101 Dalmatians was a hit movie, there was a huge spike in sales of this rather unusual breed - a breed which is certainly not for everyone. This results in unqualified breeders and puppy mills churning out marginal or poor quality pets and people getting a pet that really doesn't suit them. The end result can be a lot of disappointment, heartache and abandoned pets. This pattern has been repeated with various other breeds and animal species, and there is concern that the same will happen with guinea pigs as a result of the new Disney movie G-Force.
In terms of human health, guinea pigs are relatively benign. Bites and scratches are probably the biggest concern, and are often the result of improper handling. Bites can become infected from bacteria in the guinea pig's mouth or from bacteria on the person's skin. Allergies are also a potential problem. The number of diseases that are known to be transmitted by them is relatively small, and the risk of disease transmission is rather low.
Lymphocytic choriomeningitis virus (LCMV) is a concern with all rodents. It typically only causes disease in people with compromised immune systems, but can result in fatal infection. The risk of a guinea pig carrying this virus is likely greatest in animals from large rodent breeding facilties and when there is contact with wild rodents.
Ringworm is perhaps the most common infection that people get from guinea pigs (apart from infections following bites). Even healthy guinea pigs can carry the fungus that causes this disease.
Guinea pigs can carry Salmonella, but they are quite susceptible to infection and usually get quite sick. The risk of a healthy guinea pig shedding Salmonella, especially for a prolonged period, is pretty low. The risk is presumably greatest shortly after purchase.
Rabies is always a potential problem in mammals but the risk is very low with small rodents such as guinea pigs. (Very low isn't zero though, since hamsters have been sources of potential rabies exposure).
There are other potential problems too, but they are all quite rare.
The keys to reducing the risk of infection are:
- Purchase a guinea pig that looks healthy, is eating well, has no skin lesions or diarrhea, and is active and alert. Ideally, purchase an animal from a local breeder as opposed to a store that might have obtained the animal from a large breeder, via an animal warehouse, hundreds or thousands of miles away.
- Learn how to properly handle a guinea pig to reduce the risk of bites and scratches, as well as injury to the animal.
- Keep pet guinea pigs away from wild rodents.
- Use good general hygiene. Wash your hands after handling the guinea pig and after contact with bedding.
- Thoroughly wash any bites or scratches.
- Take particular care in the period shortly after purchase.
- Even though the cost of the guinea pig is less than the cost of a vet visit, a veterinary examination is important when the animal is sick. Apart from our ethical responsibility to take care of our pets, it's important to make sure that illness isn't caused by a disease that can be transmitted to people.
More information about the diseases mentioned above is available on the Worms & Germs Resources page. While we don't have a specific guinea pig info sheet yet, much of the information on the hamster information sheet also applies to guinea pigs.
Cab drivers have to put up with a lot of risks, but attacks from marauding rats probably aren't high on their list of concerns. However, a Ukrainian cab driver was recently attacked by a rat, and the rat was subsequently killed and found to be positive for rabies. The cab driver is now undergoing post-exposure treatment, and authorities are vaccinating pets and trying to eliminate mice and rats in the nearby neighbourhoods.
This is another good example of why it's important not to ignore a bite from any mammal, because rabies can affect any mammal. People often don't consider rodents a concern when it comes to rabies transmission, because most rodents would die from an attack by a rabid animal, thus preventing them from becoming infected and passing on the virus. This is probably true in most circumstances, but there have been enough reports of rabies in rodents, and potential human exposure from contact with rabid rodents, that we have to pay attention to this risk. Overall, the likelihood of acquiring rabies from a rat bite is pretty minuscule, and much less than the risk of contracting other diseases such as rat bite fever, but it's not zero. Since rabies is almost invariably fatal, even seemingly low risk situations need to be carefully assessed. In the case of this cab driver, there was definitely a risk of rabies exposure. If the rat had not been caught and tested, the potential for rabies exposure might have been dismissed, which could have had catastrophic consequences for the cabbie.
More information about rabies can be found on the Worms & Germs Resources page.
One more post about illogical and dangerous activities associated with animals and young children and I'll hopefully get off the subject for awhile. I came across this daycare's website today. Keep in mind (again) that the the Centers for Disease Control and Prevention (CDC) recommends that children less than 5 years of age not have contact with reptiles, and that the Compendium of Measures to Prevent Disease Associated with Animals in Public Settings published by the National Association of State Public Health Veterinarians states that wild or exotic animals may not be appropriate in school settings. The photo gallery from this particular daycare included some great pictures of things that you should NOT do with young children. Some of the more striking example are below:
1) Letting a large snake wrap its body around the neck of a young child.
2) Letting a young child kiss a snake.
3) Letting a child touch a turtle.
4) Letting a young child pet a pygmy hedgehog. (Like reptiles, hedgehogs very often carry infectious pathogens, including Salmonella.)
- whether anyone made sure these children immediately washed their hands after they touched the animals.
- how may kids but their hands in their mouths before they washed their hands. (Probably almost all of them, considering the "animal visit" probably went on for quite a while.)
- whether this activity took place in the same area where the children later ate lunch or a snack.
- whether the parents knew that this was going to happen.
I'm not against young children having contact with animals. I think pet contact can be very rewarding for young children. However, these individuals are at higher risk for infection and it is our responsibility to protect them. Putting them in high risk situations like these is inappropriate. Animal visitation in daycares is not necessarily a bad thing, if it involves animals that are a low risk species (e.g. dogs and cats), that are healthy, and that have been temperament tested (to show they are at low likelihood of biting). It is also important that parents provide consent for their children to participate, that good hygiene practices are used (and enforced), and that the people bringing in the animals know what they are doing.
A recent edition of the Veterinary Record contains a case report of Weil's disease in a person that adopted a feral (wild) rat (Strugnell et al, 2009). Weil's disease is a severe disease of the kidneys, liver and other body systems that can develop after acute leptospirosis (infection by Leptospira bacteria). This group of bacteria can infect a wide range of animals and is typically shed in the urine. The person that was affected adopted the rat after it was caught by her neighbour's cat. The paper says that the rat was "urinary incontinent" - not something we usually notice about rats since they are not typically litter or house trained. I presume this means the rat was urinating frequently when out of its cage, including when it was being handled. Because of this, the owner reported that she "aimed" to wash her hands after every time she touched the rat.
A couple of weeks after adopting the rat, the woman was admitted to hospital because of lethargy, muscle aches, mild abdominal pain, cough and a bloody nose. Blood tests showed that she had decreased levels of white and red blood cells, as well as liver and kidney disease. After further testing she was diagnosed with leptospirosis. She had to be treated in the ICU, but eventually made a complete recovery. The adopted rat and the other rat that she owned were euthanized by the owner's partner shortly after she was admitted to hospital. Testing of the adopted rat identified Leptospira in the kidneys.
This is another example of why wild animals should be left in the wild, and another case highlighting the need for veterinarians, physicians and public health personnel to work together.
Cowpox is a disease caused by cowpox virus. This virus is most famous for being used by Edward Jenner to vaccinate people against smallpox (which is caused by a related virus). However, despite the name, rodents are the natural host of cowpox virus, not cows. Most human cases of cowpox are associated with contact with rodents. Cats are another important source of human cowpox infection in some areas.
Cowpox infections in people are uncommon. Most cases occur in Europe, western parts of the former Soviet Union and parts of Northern and Central Asia. Outbreaks of cowpox can be associated with infection of pet rats at central breeding or large housing facilities, which results in large numbers of infected rats that are then shipped to many different places. Recently, outbreaks of rodent-associated cowpox have been reported in Germany and France. It is suspected that these infections are associated with a large rat breeder in the Czech Republic, however this has not been confirmed.
Cowpox causes typical "pox" lesions, like those that are seen with chickenpox. Only a single lesion is present in most cases, but multiple lesions can develop. Flu-like symptoms such as fever and fatigue, as well as enlarged lymph nodes, are also common. Severe, even fatal, disease can occur in individuals with a weakened immune system, but in most people cowpox infection causes only mild illness and resolves without treatment.
Cowpox is not a concern in many areas of the world. In regions where it is present, basic, common-sense precautions can reduce the risk of infection.
- Contact with infected animals should be avoided. Cats are an important source, and cowpox should be considered in any cat with appropriate skin lesions in an endemic area. The same should apply to rats with skin lesions.
- Gloves should be worn when handling cats and rats with skin disease, and hands should be washed immediately after glove removal.
- If skin lesions are identified on a rat, particularly over the feet, ears or tail, the animal should be examined promptly by a veterinarian.
- Don't buy any rat with skin lesions, and if possible, avoid buying rats that were bred and/or housed in facilities with a very large number of other rats.
Rats can be really interesting pets. They can be quite social and are interesting to watch. Being larger than hamsters and gerbils, they can also be more easily and safely handled. They can still bite, however, particularly if they are not properly socialized and/or they are handled by people who don't know how to do it properly. Even though rats have tiny teeth, bites can still cause problems. One concern is rat bite fever. This disease is actually caused by two completely separate bacteria. Streptobacillus moniliformis is the most common cause in North America and Europe, while Spirillum minus is the main cause in Asia.
I'll focus on Streptobacillus moniliformis today. This bacterium is very commonly found in the mouths of healthy rats. Up to 100% of rats can be carriers. It doesn't cause disease in the rats, but it can be transmitted to people by bites or scratches. It can also be spread simply by handling rats (especially if a person has any cuts or broken skin), and through close contact with rats' mouth, such as kissing and sharing food (yes, some people do).
In most people, rat bite fever causes a high fever, headache, chills, vomiting, joint and muscle pain and a rash, most commonly over the soles of the feet, palms of the hands and the extremities. While the disease will resolve on its own in many cases, treatment with antibiotics is indicated because severe complications such as inflammation of the heart, pneumonia and meningitis can also develop.
Common sense can help reduce the risk of rat bite fever.
- Assume all rats are carrying S. moniliformis in their mouths.
- Only handle rats if you know how to do so properly, and if you know the rat is amenable to being handled. Avoid contact with the rat's mouth (e.g. kissing).
- If you have open sores or cuts on your hands, avoid handling rats or wear gloves.
- Always wash your hands thoroughly after handling a rat or cleaning its cage.
- Thoroughly clean any bites from any rodent immediately with lots of soap and water.
- If you develop signs consistent with rat bite fever after being bitten, consult your physician as soon as possible, and be sure to let your physician know about the bite.
If your veterinarian suspects your pet may have ringworm, there are several different ways he or she may test for the causative fungus (a dermatophyte) on your animal's fur and skin. Some of these techniques are more useful than others in different situations.
- Wood's lamp: A Wood's lamp is simply a special ultraviolet light. Approximately half of all Microsporum canis strains (the most common species of dermatophyte that causes ringworm in cats and dogs) will fluoresce blue-green under such a light. This type of testing is obviously very easy to perform. However, other debris in an animal’s hair coat may fluoresce as well, and other species of fungus that cause ringworm do not fluoresce, so this test is not useful by itself in most cases.
- Microscopy: Sometimes ringworm fungus can be seen on hair shafts from an infected pet when examined under a microscope. However, it is easy to confuse other debris and structures for dermatophytes. Also, not every hair on an infected animal will carry the fungus, so it's possible to miss the infected hairs altogether with this test.
- Fungal culture: The best way to diagnose ringworm is to culture the fungus from the infected individual (person or animal). In animals, one of the best ways to collect a sample for culture is to comb over all the fur and skin with a new toothbrush, and then try to grow dermatophytes from the toothbrush. This allows the fur from all over the animal to tested, rather than just one little clump of fur plucked from one area. It can also make it easier to get a sample from the face and paws of cats, which is where these animals often carry the fungus. Although fungal culture is the best way to diagnose ringworm, remember that fungal culture takes much longer than bacterial culture – instead of days, it may take up to three weeks to grow some dermatophytes.
It's also important to remember that dogs, and more often cats, may carry dermatophytes on their fur even when they look healthy. A positive fungal culture from an animal with skin disease, particularly a cat, does not necessarily rule out other diagnoses, so your veterinarian may still recommend other tests as well. However, any animal with ringworm should be treated to prevent spreading the infection to other animals and people.
A report about the health risks in children associated with nontraditional pets was recently published in Pediatrics, the official journal of the American Academy of Pediatrics. The report also discusses diseases associated with animals in public settings such as petting zoos and pet stores. Although contact with pets and animals can be beneficial to growth and development in children, it is very important to be aware of the risks associated with certain kinds of animals. Physicians, veterinarians and public health personnel can help parents select appropriate pets in order to maximize the benefits while minimizing the risks to children.
One of the most important pathogens discussed in the report is Salmonella. Although Salmonella can be transmitted by many animal species, including traditional pets like dogs and cats, it is a particularly high risk with certain other kinds of pets, including reptiles, amphibians and baby poultry (chicks and ducklings). It has been estimated that direct or indirect contact with reptiles or amphibians is responsible for 6% of all sporadic Salmonella infections in the US, and 11% of cases among people younger than 21 years. There is also a relatively high risk of Salmonella transmission associated with animal-derived pet treats, such as pig ears, and raw meat.
The report makes several recommendations about how to reduce the risk of infection, injury and allergies from nontraditional pets, many of which you may have seen before on the Worms & Germs website. Just a few of these are:
- Always wash your hands after contact with animals, animal products or their environment, and after contact with animal-derived pet treats.
- Supervise hand washing for children less than five years old
Children less than five years of age and individuals with weakened immune systems should avoid contact with reptiles, amphibians, rodents, ferrets and baby poultry. These animals:
- Should not be kept as pets in households where children less than five years of age or individuals with a weakened immune system live.
- Should not be brought to childcare centres.
- Should not be allowed to roam freely in ANY house or living area.
- Should not be permitted in kitchens or anywhere food is prepared.
More information about Salmonella in pets and the risks associated with feeding raw meat and animal-derived treats to pets can now be found on the Worms & Germs Resources page.
For more information on ringworm, see the Worms & Germs post Ringworm: Skin fungus by any other name. The photos here show ringworm lesions on a person's arm and on a cat's face, respectively. (Photo credits: A. Yu, Ontario Veterinary College)
Over the past several years, studies have shown that many environmental disinfectants sold and labeled for use against the fungi that cause ringworm (which are called dermatophytes) in animals and people are, in fact, not effective when used in households and veterinary clinics. The problem is the chemicals are typically tested against a suspension of the organisms in a test tube, but in the “real world” the fungi are usually found on small fragments of infected hairs. Its possible that the hair shaft protects the fungus from the actions of some disinfectants.
There are a few disinfectants that have been shown to be effective against dermatophytes even when they are found on infected hairs and skin cells in the environment. The most readily available one is household bleach, used at concentrations of 1:10 to 1:100. Other effective products include Virkon-S® (a detergent-peroxide based product) and Peroxigard® (an accelerated hydrogen peroxide product) . An environmental spray containing enilconazole (an antifungal agent that is also found in the topical medication Imaverol®) was also found to be very effective. This product is not approved for household use, but it is approved for use in catteries. It is also licensed as a topical treatment for dogs and horses in most of Europe and Canada.
Eliminating ringworm from the household or clinic environment can be difficult, because the fungus can be found anywhere that an infected animal (or person) sheds hair or skin cells. Here are some guidelines for environmental disinfection of dermatophytes:
- All bedding, brushes, combs, rugs, cages, etc. should be vacuumed, scrubbed, and washed with hot water, detergent, and 1:100 chlorine laundry bleach, or another effective disinfectant (see above). It is best to throw out any items that cannot be thoroughly disinfected.
- Walls, floors, lamps, etc. should be scrubbed and cleaned in a similar manner.
- Carpeted areas may be impossible to effectively decontaminate. If possible, remove the carpet and either wash in hot water and bleach, or discard it. Otherwise, frequent vacuuming with immediate disposal of the collection bag is necessary.
- Vehicle interiors should be decontaminated as much as possible in a similar manner.
- Curtains can be “dry-cleaned” at a professional cleaner.
- Clean heating vents (from the house furnace) as well as possible. If the house is heated by hot air, change the furnace filter once weekly throughout the decontamination process.
- Cleaning and disinfection of the environment should be repeated at least once every 4-6 weeks (the more often, the better) until all affected animals and people have eliminated the fungal infection.
Obviously, environmental clean-up for ringworm is quite an undertaking. If infection can be identified early, lesions can potentially be kept covered and movement of pets can be restricted to reduce the extent and amount of environmental contamination.
Special thanks to Dr. Anthony Yu (one of the veterinary dermatologists at the Ontario Veterinary College) for providing much of the information in this post, as well at the photos.
Ringworm infection is not caused by a worm at all - it's actually a skin infection caused by certain kinds of fungus called dermatophytes. The scientific name for ringworm is dermatophytosis, or dermatomycosis. Some of the more common zoonotic species of dermatophytes found in animals include Microsporum canis, Trichophyton verrucosum, T. equinum, and T. mentagrophytes. There are also some dermatophytes that are primarily transmitted from person to person that are not carried by animals. These include the fungi that cause athlete's foot and jock itch.
Like many fungi, dermatophytes grow best in warm, moist environments, but they can grow almost anywhere on the body. They tend to grow around hairs and in the superficial layers of the skin, and the infection can be quite itchy. A ringworm skin lesion tends to spread out from one point on the skin, causing hairloss as it progresses, resulting in a bald patch (see picture right). The outside (most active) edge of the infection often appears as a red ring, from which "ringworm" gets its name. The centre of the lesion may begin to heal, and the hair may start to grow back, even as the bald patch gets bigger. It may take anywhere from a few days to a few weeks for visible lesions to develop after a person or animal has been infected. (Photo credit: A. Yu, Ontario Veterinary College)
Ringworm is quite contagious. The fungi are present in the large numbers on hair and skin cells that are shed by infected individuals. People or animals can be infected through contact with these infected hairs and skin cells, either directly on the affected person or animal (i.e. direct contact), or on things like clothing, blankets, hairbrushes etc. that have touched the affected skin (i.e. indirect contact).
Ringworm occurs all over the world, but no one knows exactly how common it is because there are so many different kinds of fungus that cause it, it's not reportable, and many cases probably go undiagnosed. Signs of ringworm in animals are often the same as in people, however not every animal that is infected with ringworm develops signs of infection. It has been estimated that ~90% of cats that are carrying dermatophytes do not show any signs of infection, but they can still transmit the fungus to other animals and people. (NB: this does NOT mean that ~90% of cats carry dermatophytes!) Almost any animal can be infected by at least one dermatophyte or another - cats, dogs, rabbits, rodents... even horses and cattle!
- Early identification of ringworm is important to reduce the risk of transmission to people and other animals. If your pet develops bald patches, particularly if they're itchy, it should be examined by your veterinarian to determine if a fungal infection may be present.
- If you or anyone in your household develops an area of skin that appears infected (especially if it appears as a red "ring"), keep it covered with a piece of clothing or a bandage and see your doctor.
- Most cases of ringworm can be treated with either topical (e.g. ointments) or oral anti-fungal medication.
- Clean your pet's grooming supplies (e.g. brushes, combs) regularly.
- Always wash your hands after handling your pet.
Watch for another Worms & Germs blog post about ringworm and how to clean up if you or your pet is infected, coming soon! More information about ringworm and dermatophytes can be found on the CDC's Dermatophytes website.
You may notice a recurring theme in many of our posts and on virtually all of the information sheets on the Worms & Germs Resources page: an emphasis on handwashing. There is increasing emphasis on hand hygiene (i.e. hand washing and use of alcohol hand sanitizers) education in hospitals because the hands of healthcare workers are a major (if not the most important) means of disease transmission between patients. Despite hand hygiene being easy, cheap and effective, people rarely wash their hands as often as they should, and they often don't do it properly.
Most of the research about hand hygiene that has been published has focused on its use and impact in human hospitals, but this area is now also being studied more with regard to animals and veterinary medicine. A study published earlier this year in Veterinary Microbiology provided more evidence that hand hygiene is a critical infection control measure when dealing with animals. The study, coordinated by Dr. Maureen Anderson (of Worms&Germs fame) looked at MRSA carriage rate in veterinarians who work with horses. In addition to finding a high rate of MRSA carriage among these veterinarians (which was consistent with other reports indicating that equine vets are at higher than average risk for exposure to MRSA), the study looked at factors associated with MRSA carriage. Vets that reported routinely washing their hands between farms and those that reported washing their hands after contact with potentially infectious cases had a significantly lower rate of MRSA carriage. That should come as absolutely no surprise, but it's one more piece of evidence that we need to pay more attention to this routine infection control measure, in human hospitals, in veterinary environments and in households.
Remember, the 10 most important sources of infection are the fingers on your hands!
Hamsters can be wonderful pets, and overall, hamsters are relatively low-risk when it comes to diseases they can potentially transmit to humans. However, they can sometimes carry bacteria like Salmonella in their feces, and the virus that causes lymphocytic choriomeningitis, to name a couple. But there are a few simple things you can do to help greatly reduce the risk of transmission of these and other diseases from hamsters. Doing many of these things will also help keep your hamster as healthy as possible. It is very important to learn about what a hamster needs and how to take care of hamster (or any kind of pet) before you decide to get one.
Here are a few important hamster care tips to keep in mind:
- Keep your hamster in a clean enclosure with good ventilation and enough space for your hamster to have separate areas to eat, sleep, exercise and poop/pee.
- Prevent contact with wild rodents. This means keeping your hamster in its cage and not letting it roam around the house. Also ensure that your hamster cannot escape from its cage and wild rodents cannot get into the cage.
- Most importantly, always wash your hands after handling your hamster.
Also check out the new information sheets about hamsters posted on the Worms & Germs Resources page!
In people, there are detailed protocols for avoiding blood exposure in healthcare situations, and protocols for managing people exposed to human blood in hospitals and in the community. This is mainly driven by concerns about HIV and hepatitis viruses that can be transmitted by contact with blood. But these viruses are not present in animals, and the risks of transmission of disease from pets to people through blood are very low. Even contact with blood from a rabid animal is not considered rabies exposure, because the virus is found in the saliva, not the blood. This has led to a rather cavalier approach towards blood exposure in veterinary medicine, which is understandable but not ideal. New infectious diseases continue to emerge in animals and people, and eventually there is likely to be one that can be transmitted between species by blood. Therefore, it is prudent to try to reduce exposure to animal blood when possible, but without getting overly concerned (or paranoid).
- Direct contact with animal blood should be avoided whenever possible.
- In particular, avoid getting animal blood on any cuts, scrapes or other broken skin, and avoid getting the blood in your mouth, nose or eyes.
- If you do get animal blood on your skin, wash it off as soon as possible.
- While it is extremely unlikely for a person to get sick from touching animal blood, make sure you tell your physician about the incident if you do become ill.
No...hedgehogs aren't sneaking out of their cages and attacking people as they sleep. Rather, they can carry a variety of microorganisms that can be transmitted to people. There have been a few reports describing infections associated with hedgehogs, particularly Salmonella and ringworm. An excellent report in the journal Emerging Infectious Diseases highlighted the diseases hedgehogs have been shown to, or could, transmit to people. Hedgehogs don't have to be sick to be a source of infection.
Hedgehogs have been available for years, but they may be a fad pet at the moment. One breeder is quoted as saying “They are going up these last two months we actually have a waiting list about twenty people,” said Sarah Roberts a breeder in Mansfield. “That's never happened in the year’s of breeding we've done.”
While any pet could transmit infections to people, certain pets are higher risk. Overall, species that are rare or 'fad' pets may be of greater concern because we simply don't know much about them (i.e. what diseases they can transmit, how to reduce risks...).
These small creatures can probably be safe pets in some households, but are they really better than other species? You probably should not have a hedgehog if you or someone else in the household has a compromised immune system or if you have small children. If you do have a hedgehog, don't let it roam freely in the house and wash you hands after handling it.
A woman whose husband died of lymphocytic choriomeningitis virus (LCMV) infection is suing a pet store. The suit alleges that a hamster purchased at the store was the source of infection of a person, who subsequently suffered a fatal stroke (unrelated to the infection). The hamster-owner’s liver was donated to the Plaintiff’s husband, who died of LCMV infection a month later. Two other organ recipients died and the hamster was eventually identified as the source.
LCMV is a virus that can cause encephalitis and/or meningitis (inflammation of the brain and associated tissues). Human cases are typically associated with rodent contact; both pets and wild rodents. Infected rodents can appear to be healthy. People can be infected through bites or direct contact with rodents, their droppings, urine, bedding or other contaminated materials. Pet-associated infections are rare, and are of greatest risk in people with compromised immune systems, such as transplant recipients, and pregnant women.
Some key points from this report and LCMV in general are:
- All types of pets, even small ones, can transmit infection.
- Sometimes exposure to infectious agents is unavoidable. You’re not going to turn down a donated organ on the rare chance that the donor had an obscure and undiagnosed disease.
- People that are at higher risk for infectious diseases, such as transplant patients, should consult with their physician and veterinarian before obtaining a new pet.
- Appropriate controls should be used to reduce contact of people and pet rodents with wild rodents
- Wash your hands after touching a rodent or its environment
More information about hamsters and lymphocytic choriomeningitis virus is available in the Resources area.
INFORMATION SHEETS specifically for KIDS, for VETERINARIANS, for PHYSICIANS and for PUBLIC HEALTH PERSONNEL are also available on the Worms & Germs RESOURCES page!
Click on the highlighted topics below for information sheets. Topics that are not highlighted are in development and coming soon. Sheets for other animal species and diseases are also under development and will be added when they are available.
- Your veterinarian and physician are your ultimate resource for information about the health of your pets or your family.
- Information provided here is accurate to the best of our knowledge, but infectious diseases can be unpredictable and these sheets are for general information purposes only.
- There can be great variation in disease risks in different geographic areas. The information provided was developed for Ontario, Canada, but most of the information is relevant for other regions as well.
2012 International Clostridium difficile Symposium
2012 International Conference on Equine Infectious Diseases IX
2011 ASM-ESCMID Conference on Methicillin-resistant staphylococci in animals
- Miconazole susceptibility of MRSA and MRSP
- Livestock associated MRSA in community hospitals in Ontario
- Equine hospital MRSA surveillance
- Biofilm production by S. pseudintermedius
- Methicillin-resistant staphylococcal pyoderma in dogs, and impact of treatment on colonization rates
- Surgical site infections in a small animal hospital
2011 University of Guelph Centre for Public Health and Zoonoses Symposium
- Pet ownership, interactions and animal-associated disease risks in Canadian households
- Metagenomic investigation of the oral microflora in healthy dogs
2011 Canadian Animal Health Laboratorians Conference
2011 Canadian Association of Clinical Microbiology and Infectious Diseases
- 2011 American College of Veterinary Internal Medicine Forum, June
- 2011 ASM-ESCMID conference on methicillin-resistant staphylococci in animals, Sept