Pet food/Salmonella outbreak
An article released today in the journal Pediatrics (Behravesh et al, 2010) provides more information about a salmonellosis outbreak linked to pet food. The outbreak itself is old news - I commented about it almost two years ago. What is new is the detailed epidemiological analysis of the outbreak, and there is some interesting information in the paper that is worth reporting. Here are the highlights:
Almost 50% of people who were infected were kids two years of age or younger.
- That's not too surprising considering kids less than five years of age are a high-risk group for getting sick after being exposed to Salmonella.
Households with sick people were almost 7 times as likely to have recently purchased the affected food.
- This provides good evidence of the link between the contaminated food and disease.
The Salmonella strain that was found in people was also found in bags of pet food at the manufacturing plant, samples from the manufacturing plant environment, and fecal samples from dogs that had eaten the food.
- This is pretty convincing evidence that the food was the source. Because they were able to type the Salmonella strain in people and it was an uncommon strain, and they then found the same uncommon strain in food, animals and people, it paints a pretty clear picture of what happened.
Illnesses occurred over a 3 year period.
- This is pretty concerning. This was more than a little lapse at a plant that led to contamination of a single batch of food or a short term event. This was a major failure in quality control that was undetected for a long period of time, resulting in at least 79 human infections in 21 US states.
A cluster of infections caused by the strain involved here, S. Schwarzengrund, was identified early in the outbreak. However, a link with pet food was not considered until the following year.
- That's unfortunate but maybe not surprising. There are a lot of other more likely sources of infection that were probably focused on initially. "What kind of pet food do you feed your dog?" was unlikely to be a routine question asked of people with infections. Identification of outbreaks caused by uncommon events is difficult and typically takes more time.
People that fed their dog in the kitchen were 4 times as likely to have an infection.
- Feeding a pet in the kitchen presumably increased the chance of cross-contamination with human food or contamination of the food preparation environment.
The cause of contamination was never identified. The authors of the paper suspected that contamination occurred after extrusion (the process during which the kibble is formed), which makes the most sense. The extrusion process results in high enough temperatures to kill bacteria like Salmonella. Possible causes of contamination include contaminated equipment used after extrusion, cross-contamination of pre- and post-extrusion food and contamination of substances (e.g. flavour enhancers) sprayed on kibble after extrusion. The fact that Salmonella was found in the room where materials were sprayed on the kibble supports this further.
In general, dry pet food is quite low-risk in terms of Salmonella contamination, but just like with other non-raw-animal products such as lettuce, tomatoes and sprouts, contamination can occur and human infections can result. The best way to reduce the risk is to use good general hygiene practices, particularly washing hands after handling food, keeping pet food and pet food bowls out of kitchens and limiting contact of young children and other high-risk individuals with pet foods.
Frozen mice recall: Salmonella
MiceDirect, a company that sells frozen mice, rats and chicks as reptile feed, has issued a recall because of Salmonella contamination of their product. Contaminated critters have been sold across the US (except Hawaii) through mail order and pet stores, and recalled product codes can be found in the FDA recall notice. Contamination isn't a big deal for the reptiles, since carriage rates for Salmonella are already high and they are usually healthy carriers. The concern is for people who handle the frozen rodents/chicks (or who can be exposed indirectly from contaminated surfaces in the home). There have been previous outbreaks of human Salmonella infections associated with contaminated frozen rodents.
Unlike many other recalls where the product is recalled because of contamination but without evidence of human illness, human illnesses suspected to be linked to contaminated reptile food have been identified in 17 states. In reality, reported cases may be the tip of the iceberg, and I suspect that if cases in 17 states are confirmed, there will be (or may already be) many more. Other details regarding these cases and the recall, such as the strain of Salmonella involved, haven't been released.
In response to this problem, the FDA report and the company website indicate that products from MiceDirect will be irradiated. It's not clear if this will be a standard protocol from now on, or whether it's a short-term response to the contamination problem. Considering the repeated outbreaks associated with frozen reptile food, irradiation sounds like a good standard practice. Perhaps the best way to help make (or keep) it a standard practice industry-wide is for consumers to vote with their wallets: ask for irradiated or otherwise treated (e.g. high pressure pasteurization (although I'm not sure what that would do to a mouse)) feeds to reduce the risks of contamination.
Because of recurrent problems with contaminated frozen reptile feed, if people are not buying products that are treated to eliminate contamination, they should assume that all such feed is contaminated and handle it accordingly. That means using basic practices such as:
- keeping frozen reptile feed away from human food
- if defrosting it in the refrigerator, keep the reptile feed in a sealed container that is not used for human food and that is disinfected afterward
- washing hands after handling the feed
- disinfecting any potentially contaminated surfaces that come in contact with the feed
- discarding uneaten food promptly, since Salmonella can multiply as uneaten food sits in the open, especially in a nice, warm reptile terrarium
A link to more information about MiceDirect is available through a post on Barfblog.
Livestock-associated MRSA in dogs
A study we just published in the journal Veterinary Record (Floras et al 2010) described an MRSA outbreak in a dog breeding kennel. That's a little unusual in itself, but considering how MRSA is spreading amongst the dog population, it's not really astounding. What was unique about this outbreak was the strain of MRSA that was involved, sequence type 398 (ST398).
ST398 MRSA is commonly referred to as livestock-associated MRSA, since this strain seems to have originated in pigs, and is commonly found in pigs and calves in some regions of the world. It can also infect people, and high rates of carriage of this MRSA strain can be found in pig farmers, pig vets and other people with close contact with livestock. In some areas of Europe, this strain is a big problem, accounting for a large percentage of human MRSA infections. Interestingly, it seems to be a rare cause of illness in people in North America (at least at the moment).
Dogs seem to be innocent bystanders when it comes to MRSA. The vast majority of MRSA strains found in dogs are common human strains, indicating that, ultimately, MRSA in dogs originated in people. There are only two other reports of dogs with ST398, both from Europe. One was a dog with a skin infection. The other was a healthy dog (a carrier) who was owned by a pig vet.
This kennel outbreak involved a larger number of dogs, including both healthy carriers and sick dogs. Overall, MRSA was isolated on at least one occasion from 23/42 (55%) dogs in the kennel. In a couple of litters, most of the puppies were identified as carriers, but fortunately most stayed healthy. MRSA caused skin infection in one puppy and mastitis in a mother dog, and was also found in the respiratory tract of a puppy that died (although it may or may not have been the cause of death).
The source of the ST398 was not identified. One of the owners worked on a pig farm, but MRSA was not isolated from either owner. It's most likely that the owner did bring MRSA home from the farm, either as a transient carrier (in their nose) or as a contaminant on their skin. Regardless, once it got into the kennel, it was able to move between dogs, either from dog-dog contact or with the help of human hands. Fortunately, ST398 MRSA carriage by dogs seemed to be transient in this situation, which is consistent with what we know about carriage of other strains. MRSA is not really adapted for long-term survival in dogs, so they only carry it for short periods of time. That's a big advantage when it comes to trying to control this pathogen.
While we have to be careful to not over-interpret data from only a few studies, this report indicates that ST398 can cause disease in dogs and it can be present in apparently healthy dogs. It can also be spread relatively easily amongst dogs in a breeding kennel situation. While a pig-link was not confirmed, it's reasonable to suspect that dogs with contact with pigs (and perhaps other livestock) might be at higher risk of developing ST398 infections, as is the case with people.
This is a perfect example of the one medicine concept, and why we need to think about infectious diseases in broad terms, not just focusing on specific populations or species. This situation involved a pig Staphylococcus aureus that somehow acquired methicillin-resistance, spread widely around the world (most likely in pigs, initially), spread to people, and then likely spread to another species, in this case dogs.
Different shelter outbreak, different issues
An Indianapolis area shelter recently put out a public call for foster homes to help deal with an outbreak of respiratory tract disease in cats. They were trying to find homes for sick cats, presumably as part of a plan to depopulate the humane society to help control the outbreak. This is what a lot of people have said that the OSPCA should have done in the recent ringworm outbreak in Newmarket, Ontario. But these are two completely different issues.
The main difference is the nature of the infection. Feline upper respiratory tract viruses only infect cats. Therefore, foster homes that don't have cats can take them safely. Ringworm can affect people and other animals. Every household has some individuals that are susceptible to ringworm. Therefore, cats with respiratory tract infections pose no risk to appropriate foster households, while the same can't be said about ringworm. Reportedly, six staff members and two volunteers have contracted ringworm so far in the Newmarket outbreak.
Fostering a cat with viral respiratory tract disease is relatively easy. You just treat it like any cat and watch for signs of worsening disease or secondary infection. Fostering a cat with ringworm is not as easy. You need to keep it isolated to keep it from spreading the infection through contact with people and animals, and to prevent contamination of the household environment. You need to wear proper protective clothing when handling it. You probably need to treat it, such as giving it a bath twice a week and/or oral medication every day. It's not rocket science, but it takes a lot of time and commitment. Importantly, it takes long-term commitment, since you need to do this for weeks or months. You can't get into a situation when foster homes get bored and want to return the animal before it is considered non-infectious.
In all outbreaks, one of the most important steps is to figure out what happened and why. A detailed (and ideally arms-length) investigation needs to be performed to identify problems with animal management, medical care, general protocol, communications and other areas, and to make any required changes to reduce the risk of it happening again.
Ringworm recommendations
The OSPCA has changed their plans for management of the ringworm outbreak that is ongoing in a Newmarket, Ontario shelter. Now, some (hopefully all) remaining animals will be fostered out to local veterinarians while the situation is being brought under control.
One question that has been asked widely in the press and by the public is why these animals haven't simply been sent to foster homes. Particularly now, with all the attention, there would presumably be many people willing to take in these pets. However, putting animals infected or potentially infected with ringworm into foster homes is a controversial and potentially problematic situation, because ringworm can be spread easily to people and other animals in the household. Sending out an animal that is or may be shedding a zoonotic disease is a tricky situation, and one that can't be taken lightly. Additionally, proper management of these animals can take significant time and effort.
A better approach is to send the animals to places where they can be properly, safely and humanely isolated and treated. Veterinary clinics are a logical option, and a request has been sent to clinics in the area to take animals for quarantine and treatment. The reason veterinary clinics are being solicited is that many clinics have the ability to properly house these animals in isolation units and have the expertise and commitment to properly treat them.
Nonetheless, this is no small favour to ask of these veterinary clinics. Just as taking an infected pet into a household carries some risk, taking these animals into a clinic is also associated with some risk of transmission to people and other animals. However, with proper facilities and protocols, and the donation of sufficient personnel hours to implement those protocols, the risks should be minimal. To facilitate this, we have developed an information sheet with infection control and treatment recommendations for veterinary clinics. For anyone else who is interested, the document can be found here and on the Worms & Germs Resources page under Information Sheets For Veterinarians.
Image: Ringworm lesions on the paws of a dog. Although this is how "classic" lesions tend to appear, clinical signs of ringworm in pets can be highly variable. (click image for source)
Why do shelter outbreaks occur?
The recent ringworm outbreak in a Newmarket, Ontario shelter has focused a lot of attention on shelter outbreaks, outbreak prevention and management. A common question that I've been getting in the last couple of days is "Why do these outbreaks occur?"
There are many reasons why an outbreak can develop. I have no first-hand knowledge of the Newmarket outbreak, and don't know what prompted that outbreak, but here are some general causes of outbreaks.
Inadequate protocols:
- Shelters need clear and logical protocols for all things dealing with animal care. This needs to include aspects like where new animals go, what types of evaluation and monitoring are performed, vaccination and deworming plans, when animals need to be tested or treated, when they can be released from quarantine, how to record and report infectious diseases, how to clean and disinfect areas and items, personal hygiene, and protective clothing, among other things. These protocols need to be in writing and accessible to all personnel.
Inadequate training:
- Shelters often have large numbers of staff, many with minimal training in animal husbandry or medicine. Proper training is required to ensure that they know what to do and why. (The latter is important because if people know why they need to do something, they are more likely to do it.) Training programs need to be well-structured and formal, not casual, follow-someone-around-and-see-what-they-do training.
Inadequate supervision:
- Even with good protocols and training, the facility managers need to ensure that protocols are followed. They need to enforce protocols and address problems with compliance. They need to make sure their protocols are up-to-date and consistent with best practices.They need to monitor disease rates and concerning trends of illnesses, so that problems can be identified early. They need to know when to get advice and who to ask (see below).
Infrastructure challenges:
- Some facilities (or actually, most facilities) are not well designed in terms of infection control. That makes it harder to prevent disease transmission and contain problems. Limitations in isolation/quarantine areas may result in mixing of new (and more likely infectious) animals with those ready for adoption. Few sinks may reduce handwashing, a key component of infection control. A facility that is too small for the animal load results in cramming in too many animals.
Poor awareness:
- If staff (from management on down) don't understand the issues, they may not act appropriately. Proper routine preventive measures and outbreak response measures may not be convenient, easy or cheap. There must be motivation to implement them. If there is little awareness of the problem, people are less likely to do what is needed.
Failure to act appropriately when the first cases are identified:
- It is much easier to contain a problem when you act early. If only a few animals have been infected or exposed, it's much easier to take aggressive measures. Once you get a large number of infected or exposed animals, it's much harder to do things like properly separate different groups (e.g. infected vs potentially infected vs non-infected). The more animals affected, the greater the chance of further transmission. Keeping your head in the sand and hoping things will go away can result in a small containable outbreak becoming a facility-wide, difficult-or-impossible-to-contain outbreak.
Failure to get good advice:
- People working in shelters can't be expected to be experts in all aspects of infectious diseases and infection control. That's why getting good advice (and following it) is critical. Sometimes, people don't ask for advice or don't go to the real experts. This can happen because they don't really understand the problem, don't know who to contact, don't want to admit they don't know everything or don't realize they are in over their heads. A little good advice, especially early, can make a world of difference.
Bad luck:
- Ultimately, you can have an exceptionally run facility and still get an outbreak. By the nature of what shelters do, they bring in a lot of animals with potentially infectious diseases and have many animals that are at higher risk of getting sick if they get exposed. It's much less likely to occur with a good infection control program, but you can never 100% guarantee nothing bad will happen. You can't do much about this. All you can do is make the best program possible, and try to limit any problems that develop.
Ringworm at the OSPCA
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.
For more more information about ringworm, download the information sheet from the Worms & Germs Resources page, or check out our archives.
Photo source: yorkregion.ontariospca.ca via www.thestar.com
Dogs also affected in 2007 Australian equine flu outbreak
In 2007, there was a massive equine influenza outbreak in Australia. A large number of horses were infected in this country that was previously equine influenza-free, and there was tremendous economic disruption caused by containment measures. It turns out horses weren't the only animals infected. A report in the April edition of Emerging Infectious Diseases describes influenza infections in dogs associated with the equine outbreak.
In some ways, it's not too surprising. Canine influenza in North America is caused by H3N8 influenza that moved from horses to dogs. Similarly, H3N8 influenza of equine origin has been identified in dogs in the UK. So, while it's an uncommon event, we know that in some situations, the "standard" equine H3N8 influenza virus can infect dogs.
The first dog that was diagnosed lived near a large horse stable. The dog developed typical signs of influenza: decreased appetite, lethargy, nasal discharge and cough. After the first dog was identified, other dogs were noted to have similar signs, including dogs whose owners had contact with infected horses and dogs that had contact with other sick dogs. Some dogs had severe infections. Influenza was diagnosed through detection of antibodies in their blood, and the influenza virus was isolated from one dog. The virus that was isolated was the same as the one present in horses (and different from that in US dogs).
For influenza to jump between species a few things have to happen.
- First, the virus has to be able to infect the other (non-natural) species. This can happen because the virus is inherently able to infect different species or because of a random viral mutation that allows for infection of the new species.
- Second, the virus must encounter that host (in this case, dogs). It must then be able to multiply within the new host.
All this can happen with or without development of disease. For the virus to truly establish itself in the new species and spread (like canine flu did in the US):
- The virus must be able to multiply well in the new host, and adequate virus levels must be produced for the new host to be a source of infection to other individuals.
- The new host must come into contact with other susceptible individuals.
- The virus must be able to infect new hosts readily enough to maintain infection in the population, instead of dying out after a couple transmission cycles.
In these Australian cases, while it is apparent that equine flu was able to infect dogs, there was no clear evidence that perpetual dog-to-dog transmission occurred. Influenza virus was rarely detected in nasal secretions from infected dogs, making it unlikely that the virus would spread between dogs. Therefore, the virus was not able to establish itself in the dog population. This means it ended up being only an interesting situation that affected a limited number of animals, instead of the creation of a new, self-propagating infection that could continue to circulate in dogs in the country.
Cryptosporidiosis from wildlife centre lambs
The May 2010 edition of Emerging Infectious Diseases contains a report about an outbreak of cryptosporidiosis in Scotland (McGuigan et al. 2010). Cryptosporidiosis is a common parasitic disease caused by Cryptosporidium, a protozoal parasite. It causes diarrhea, which is usually annoying (to say the least) but self-limiting in healthy people, but the infection is potentially fatal in people with compromised immune systems.
An investigation was launched after a single case of cyrptosporidiosis was diagnosed by a Scottish laboratory. The reason a single infection caused such concern is that it was suspected to have originated from contact with lambs at a wildlife centre, so there was potential for exposure of many people. The concerns were valid, since a total of 128 cases of cryptosporidosis were uncovered during their investigation, and 117 of the people affected had visited the wildlife centre. Another 252 unconfirmed cases were also identified.
The investigation suggested that direct contact with diarrheic lambs was the source of infection. Lambs (and calves) are high risk for shedding Cryptosporidium, even when they're healthy. Diarrhea increase the risk of transmission from these animals even more, because diarrheic animals are more likely to (1) shed the parasite and (2) have fecal staining of their haircoats, which increases the likelihood of fecal contact for every person and animal around them. That's why young ruminants (e.g. lambs, calves) as well as young poultry are considered inappropriate for petting zoos and other similar public animal contact events. This outbreak is yet another example of why these recommendations are in place.
At the wildlife centre in this study, children were apparently encouraged to pick up the lambs, despite visible diarrhea. No handwashing facilities were near the lamb petting area and it took "considerable effort" to find a location to wash your hands anywhere on site. Alcohol hand sanitizers were available, however Cryptosporidium is resistant to alcohol. Handwashing is a critical component of disease prevention, but unfortunately it is very underused. In general, people are becoming much more aware of the need for handwashing, but even so, if handwashing facilities are not conveniently located, people tend not to go to much effort to find them. That leads to increased risk of infections, as was the case here.
Control measures at the wildlife centre implemented after the investigation included removal of the lambs (who should never have been there anyway), disinfection of the premises with bleach (although disinfecting a farm environment is very difficult, and Cryptosporidium is also resistant to bleach), and stopping direct contact between animals and visitors.
As we enter the season when there are more fairs, petting zoos and other animal contact events, facility managers need to pay attention to important factors like:
- Readily available hand hygiene facilities
- Good design to control the types of human-animal contact and to steer people towards hand hygiene stations
- Appropriate animals: no calves, lambs or chicks
- Proper supervision of people and animals
A little common sense goes a long way. The goal is to set up these events so that there is still a beneficial impact of seeing and interacting with animals while reducing (but never eliminating) the risk of disease transmission. A 100% safe petting zoo is not achievable (there's always some risk in life), but some pretty simple measures can greatly reduce the risks while still providing excellent entertainment and educational opportunities.
Raccoon vaccination in New York
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In response to ongoing problems with rabies in raccoons in New York's Central Park, a vaccination program is now underway. Raccoons are being trapped, vaccinated, tagged and then released. This is a logical response to the outbreak and one that will hopefully have a significant impact.
Trap, vaccinate and release programs can help in a few different ways. Firstly, they protect the individual raccoons that are vaccinated. However, in the bigger picture, mass vaccination is designed to protect humans and animals beyond those that are vaccinated (this is referred to as "herd immunity" - click here for a good video about this concept from a previous post). As the number of vaccinated (and therefore immune) individuals in a population increases, there's less risk of ongoing transmission of the disease (in this case, rabies), since an infected animal is less likely to encounter a susceptible (unvaccinated) individual. If, on average, an infected individual does not have a chance to infect another individual, the outbreak will eventually die out. The key is getting a high enough percentage of the population vaccinated.
For eradication of dog rabies, the World Health Organization recommends vaccinating at least 70% of dogs in a population. I'm not sure what the critical number is for raccoons, but it's presumably a similar, and reasonably high, number. Since a high vaccination rate is needed, there needs to be a concerted effort to do more than just a token vaccination program. It also helps if there's good information about raccoon numbers and distribution in the area. As long as the Department of Health is serious about this program and puts the required time and resources into it, the odds are very good that it will be successful.
2008 Australian Hendra virus recap
The latest edition of the journal Emerging Infectious Diseases contains a paper describing the 2008 Australian Hendra virus outbreak in horses and people.
In this outbreak, there were five horses infected and two humans infected. The horses predominantly had signs of neurological disease, not respiratory disease like some other reports describing this disease. Four horses died. One recovered but was euthanized for public health reasons.
Two people became infected after working with the sick horses, which represents 10% of the total veterinary staff that were exposed to the infected horses. Both people started off with influenza-like illness, which seemed to improve initially, but then signs of severe neurological disease developed. They were treated with ribavirin, an antiviral drug, as part of an experimental treatment. One of them died after 40 days of illness, the other person survived.
The authors stressed that the effectiveness of ribavirin could not be determined, but they recommend it nonetheless because of the severity of Hendra virus infection and lack of other options. Ribavirin was also used in the 2009 outbreak, but it is clearly not 100% effective since one person died there also.
A number of concerning activities occurred that put people at risk of infection, including a "percutaneous blood exposure while euthanizing an infected horses" (they didn't explain exactly what this was, but it could have been a needlestick), low use of personal protective equipment, and contact with potentially infectious body fluids. This is unfortunately not surprising since the approach to infection control (particularly in terms of zoonotic infections) is often lax in equine medicine. That certainly has to change, particularly in areas where Hendra virus may be present.
Much more information about how to control this potentially devastating virus is needed. Fortunately, infections are uncommon and it is restricted to a fairly small geographic range in Queensland, Australia.
Image source: http://animalphotos.info/
This Worms & Germs blog entry was originally posted on equIDblog on 27-Jan-10.
Salmonella from frogs
The CDC is investigating an apparent multistate outbreak of salmonellosis associated with contact with frogs. As of December 7, 48 infected people had been identified from 25 states - a pretty remarkable distribution. People got sick between June 24 and November 14, 2009. As is normal for Salmonella outbreaks linked to animals, young children have been more commonly affected, with kids under 10 accounting for 77% of cases. Fortunately, no one has died.
As part of the investigation, contact with animals was investigated and their preliminary analysis indicates contact with water frogs like African Dwarf frogs is the likely source of infection.
Amphibians often get ignored when it comes to zoonotic diseases. The risk of salmonellosis associated with reptiles is fairly well known, but not too many people think about the risk associated with amphibians. The same general guidelines for keeping and handling reptiles should be used for amphibians:
- Children under the age of five should not have contact with amphibians, nor should people with compromised immune systems.
- Hands should be thoroughly washed after handling frogs or having contact with their environment (terrarium/aquarium).
- Frogs should not be allowed to roam freely in the house.
- Aquarium/terrarium water should not be dumped out in the kitchen sink. Ideally, amphibian habitats should be cleaned outside. Care should be taken to prevent contamination of the household environment.
- Amphibians should not be kept in childcare facilities or kindergarten classrooms.
Another fatal strep outbreak at a shelter
A very poorly-written and confusing report suggests that another Streptococcus zooepidemicus outbreak is underway in dogs in a shelter in Ohio. Five of 175 dogs on the premises died suddenly of hemorrhagic pneumonia. The report variably mentioned a "virus that mutated from horses," that it's thought to be "not contagious" despite multiple dogs being affected, and that it's a "rare form of streptococcus" (a bacterium). Presumably, they are dealing with a group of dogs with Streptococcus zooepidemicus pneumonia (technically, Streptococcus equi var. zooepidemicus). This bacterium predominantly lives in horses but periodically causes infections in other species. Outbreaks in dogs are uncommon but have been reported in other shelters. I assume that cultures from the dead dogs identified the bacterium, otherwise other possible causes such as canine influenza would also have to be considered.
The statement about it not being contagious is bizzare. Obviously, it is contagious between dogs. It may have been referring to dog-to-human transmission, but while that's rare it has been reported.
The shelter is apparently treating all dogs with penicillin prophylactically (i.e. to prevent any more dogs from getting sick). There's no clear guidelines regarding management of S. zooepidemicus outbreaks in kennels. It's now known whether mass antibiotic treatment does anything helpful, but it has been used in other outbreaks. I think it's likely that these outbreaks stop on their own, rather than penicillin having a major impact, and that there's probably another underlying cause such as a viral infection to account for outbreaks of this rare disease. However, that's just speculation for now. Hopefully this outbreak will cease with whatever treatment and infection control measures they put in place (or on it's own). Hopefully a good review of routine infection control practices will be performed at the same time, as routine practices (or lack thereof) are often a major problem in shelters.
Rabies quarantine in (and of) Santa Cruz County, Arizona
A large number of rabies cases in Santa Cruz County, Arizona has lead to the rare practice of implementing a county-wide rabies quarantine. Fifty-four cases of rabies have been diagnosed so far this year, mainly in skunks. That's about twice as many as normal.
Quarantine is probably not the best description of what they are doing, but they are taking measures to improve vaccination of pets, reduce roaming pets and discourage human-wildlife interaction.
For the next 60 days, the following rules are in place:
- Dogs and cats must be vaccinated against rabies.
- Dogs must be confined to the property or on a leash.
- People are not allowed to feed wild animals.
- Pet food must not be left outdoors after sundown.
Those are all pretty standard measures that should be used anytime. It sounds like these rules already exist in Santa Cruz County but their "quarantine" means that they will be aggressive in enforcing them. Increasing enforcement is a good idea, but ongoing efforts after this quarantine period are also needed because rabies will continue to be a risk in that area.
Image source: www.acmeanimalremoval.com
Deja vu all over again: Turtles and Salmonella
You'd think, after countless outbreak of salmonellosis associated with pet turtles, that people would learn and things would start to improve. I guess not. A paper published this week in Pediatrics (Harris et al) described a large outbreak of Salmonella Java associated with pet turtles. Between May 2007 and January 2008, 107 infections were identified. The median age (the age in the middle of the range of affected people) was seven years old. Sixty percent of infected people reported exposure to turtles during the week before they got sick; 87% were small (<4 inch) turtles, and 34% were purchased at a retail store (despite the fact that the sale of turtles less than 4 inches long is banned in the US). Five infected people, all less than 10 years of age, reported kissing the turtle or putting it in their mouths.
When they compared people with Salmonella Java infection to people without the infection, 72% of people with Salmonella reported contact with turtles versus only 4% of controls.
Salmonella is far from rare but it's nothing to ignore. Thirty-three percent of infected people were hospitalized. Fortunately, no one died.
The link between turtles and Salmonella has been known for a long time. Healthy turtles can carry the Salmonella bacterium and be a source of infection, particularly for children. The sale of small turtles is banned in the US to reduce the likelihood of close contact between turtles and kids, but this law is widely flouted. An understanding of the link between turtles and Salmonella is surprisingly uncommon - only 32% of Salmonella patients in this study (and 28% of controls) reporting knowledge of this link. Clearly, there are a lot of areas which could be improved.
- If banning the sale of small turtles is truly an effective measure, then it should be enforced. "Black market' turtles are far too easy to find.
- More public education is needed, among the general population and particularly people buying turtles. You shouldn't be able to take a turtle home from a store without an information sheet about the risk of Salmonella and how to avoid it.
- People with turtles (or any reptile) need to recognize the risk and act appropriately. Good general infection control and hygiene measures are needed to reduce the risk of Salmonella exposure.
- Households with children under five years of age, or with immunocompromised individuals should not have pet turtles.
- Antibiotics are not the solution. Attempts to create Salmonella-free turtles with drugs have just led to the production of turtles carrying antibiotic-resistant Salmonella.
- Common sense needs to be a little more common. The picture above (from http://www.familylovezone.com/js_DeepAndWide.htm) was proudly posted by a parent.
More information about infectious disease risks associated with turtles can be found on the Worms & Germs Resources page.
Vancouver petting zoo outbreak numbers climb
Five more E. coli O157 infections have been linked to the Pacific National Exhibition's petting zoo, bringing the total to 18. It's very likely that the true number of infected people is higher, since mild cases are often missed because they don't go to the doctor or because testing is not performed. This situation follows a very large outbreak linked to a UK public farm and closure of some other UK petting zoos because of E. coli O157. Clearly, more effort needs to be put into proper management of these events, design of petting zoo facilities, scrutiny of animals and education of the public about infection control practices. Petting zoos shouldn't be banned, but they should be regulated and run responsibly. .jpg)
Severe diarrhea outbreak in Florida dogs
Tuttle Animal Medical Center in Florida has reported six dogs with severe bloody diarrhea, vomiting and fever, over the past month. The affected dogs were from the same general area in Sarasota County, and all but one died within 24 hours. However, care must be taken when interpreting information such as this. Apparently, most dogs were owned by people with limited finances, so it's hard to say whether they would have died if aggressive (and expensive) treatment could have been provided. A disease like parvovirus is highly fatal without treatment, but survival rates are excellent if proper treatment is provided.
Initial testing of these dogs to identify the causative agent has been unsuccessful, including a rapid in-clinic test for parvovirus. Because of limited finances, complete diagnostic testing has not been performed, and it's likely that only a very limited range of possible causes have been investigated. That's a problem with a user-pay system such as this. There's no incentive for owners of dead pets to pay for further testing that could help understand the problem and/or help other peoples' pets.
Various experts have been consulted, but it sounds like there is minimal material (e.g. saved fecal samples) to use for further testing. Trying to make a diagnosis based on clinical signs and basic laboratory data collected by the clinic during standard work-up and treatment is essentially impossible. Veterinary infectious disease expert Dr. Cynda Crawford told VIN News Service by e-mail last Wednesday "There is very little case material to work with, so am struggling with meaningful diagnostic approaches,...Everything is basically speculation at this point."
Florida's Division of Animal Industry is apparently "monitoring the situation." At this point, there's nothing that can really be done, but hopefully assistance with testing will be provided should further cases be identified. One official from this agency speculated that E. coli O157 could be the cause. That seems pretty unlikely. This bacterium can cause disease in dogs but it's quite rare. Six apparently unrelated cases due to such a rare cause seems pretty unlikely, although it shouldn't be dismissed.
A general tenet of medicine is "common things occur commonly." Situations like this are most often unusual presentations of a common disease (e.g. parvovirus) rather than a new disease. More aggressive diagnostic testing for known causes of disease, along with additional testing to try to identify new pathogens is needed if further cases are identified. Sometimes apparent outbreaks like this go away on their own without any intervention or diagnosis. Only time will tell whether this is a small local event or the "tip of the iceberg."
E. coli outbreak at a petting zoo
The latest edition of the CDC's Morbidity and Mortality Weekly Reports describes an E. coli O157:H7 outbreak associated with a petting zoo. The outbreak, which occurred at a day camp in Florida in 2007, involved 7 infected individuals. Two children were hospitalized. The same E. coli strain affecting the people was found in the stool of goats at the petting zoo.
During the investigation of the facility, it was noted that many of the general recommendations for petting zoos were followed, including providing handwashing stations, promoting hand hygiene compliance, prominent signage, and restricting eating and drinking in the zoo area. This shows that outbreaks can occur even at facilities that seem to be doing a reasonably good job of infection control. However, several key issues were identified:
- Campers were not instructed how to wash their hands properly.
- Handwashing was not carefully monitored.
- There was unlimited (and presumably not completely supervised) contact with animals throughout the day.
Numerous outbreaks of disease associated with petting zoos have been reported, often involving E. coli O157, a strain of E. coli that can cause serious or even fatal disease. This E. coli strain can be found in healthy cattle, sheep and goats. Other potentially harmful microorganisms can also be found in healthy animals of these, and other, species (particularly in their manure). Because you never know whether an animal is “potentially infectious,” taking measures to reduce the risk of disease after possible exposure is critical, particularly meticulous hand hygiene. Restricting high-risk animals (e.g. calves, baby chicks, pregnant sheep and goats) from petting zoos is also important.
Petting zoos can be great events, but carry any inherent risk of disease. More information about petting zoos and the diseases associated with them can be found in a new information sheet on the Worms & Germs Resources page. The National Association of State Public Health Veterinarians has also just released its revised Compendium of Measures to Prevent Disease Associated with Animals in Public Settings, a comprehensive document about measures to reduce the risks associated with petting zoos and other animal contact events.
Rabies quarantine in Flagstaff, Arizona
Quarantining animals that have potentially been exposed to rabies is a standard practice, but quarantining a whole town is new to me. Because of a large increase in rabies cases in the Flagstaff, Arizona area, a rabies quarantine was established on April 8th by the Coconino County Board of Supervisors. The quarantine requires all dogs and cats to be enclosed or secured on their owner's property. When off the property, animals must be on a leash that is no longer than six feet in length. All dogs and cats must be vaccinated, and low-cost rabies vaccine clinics have been held to help increase compliance with this requirement. Vaccination of wildlife using baits containing an oral form of rabies vaccine will also be performed. The quarantine also restricts feeding and interacting with wildlife. Also, people cannot leave pet food outside after sunset and all compost piles must be completely enclosed.
This is an aggressive approach to rabies control in an area experiencing a wildlife outbreak of the disease. They've implemented comprehensive but still quite practical measures that should help reduce the risk of exposure of domestic animals (and people) without a significant negative impact on pet owners. I've mentioned my concerns about rabies vaccine clinics in the past, but this is a situation where I think it's a good idea.
It's always hard to evaluate the effectiveness of outbreak measures, because you never know what would have happened if nothing had been done. Regardless, it will be interesting to see how well this quarantine works, both in terms of the number of new rabies cases they see and the response of citizens to these restrictions. It would be very useful if Coconino County personnel provide information about how things went when the quarantine is over - the information might be useful for management of future rabies outbreaks.
Fatal needle phobia: Rabies in Bali
ProMed mail reports two more rabies fatalities in an ongoing outbreak in Bali, Indonesia. The first person was bitten by a stray dog, which always must be considered a potential rabies exposure, especially in an area where an outbreak is underway. He received one rabies shot but did not undergo the whole post-exposure series because of a fear of needles, and he died.
The second person was bitten by both a stray and a pet dog, another clear indication for post-exposure treatment. She refused treatment because of a fear of needles, and also died of rabies.
These were two completely preventable deaths. The decision to forgo treatment almost certainly cost these people their lives - rabies is preventable with appropriate and timely post-exposure treatment. These cases also highlight the need for proper education of the public when it comes to rabies, both in terms of avoiding strays and the need for prompt attention when there's potential exposure to the disease. I have no idea how forcefully medical or public health personnel explained the need for proper treatment. For people that want to decline treatment, aggressive and comprehensive education is needed. Ultimately, people are allowed to make bad decisions, but we need to make sure they at least make informed bad decisions.
There are various other concerning issues with this outbreak, particularly the government's response to it. Multiple sources have apparently advised the government that aggressive vaccination and halting of dog movement between the peninsula and the mainland could contain this outbreak. So far, this has not been done. Amazingly, importing rabies vaccine into Bali was illegal until December 2008, and it is still illegal to vaccinate dogs outside of the outbreak area! The cost of vaccination has been used as an excuse not to do so. Certainly, financial issues are important in developing countries. However, the estimated cost is only about $0.50 US per dog. When one considers that this area is highly dependent on the tourist industry, they need to consider this as an investment to maintain their economy. Would you like to spend your vacation in an area with an ongoing rabies outbreak?
Rabies outbreak in Angola
A large outbreak of rabies continues to have devastating effects in Angola, Africa. While rabies outbreaks are not uncommon in some parts of the world, the number of people affected in this outbreak is remarkable. A hospital in Luanda, the nation's capital, has diagnosed rabies in at least 93 children in the past 3 months. All have died. The main source of the disease in this case is Angola's large stray dog population. Stray dogs can transmit rabies to other dogs and people through bites. The poor socioeconomic status of the country increases the risk of outbreaks like this because:
- Vaccines are not readily available (for dogs or people)
- It is difficult to organize and fund vaccination programs for stray dogs
- It is difficult to educate the general population about how to avoid and manage rabies exposure
- The healthcare system is relatively limited
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These problems, all related to a poor economy, create a "perfect storm" for a rabies outbreak. The shortage of human rabies vaccine and the high cost of post-exposure prophylaxis (PEP) makes it much more likely that people will actually develop signs of rabies after being exposed. The cost of PEP is more than the average Luanda family makes in a month.
Fortunately, the outbreak seems to be waning. However, without improvements in stray dog management (including vaccination) and access to adequate PEP, future outbreaks and problems are inevitable. It was reported that "adequate" supplies of canine rabies vaccine are now available. Hopefully, a concerted effort to vaccinate as many dogs as possible will reduce the rabies load in the canine population, thereby helping to decrease the risk to the people living in the area as well.
