Rabid cat attacks jogger
A search is on for a woman in Spring Hill, Florida who was attacked by a rabid cat while jogging. The cat apparently jumped on the woman's back without provocation while she was out for a jog. The cat was later caught and found to be rabid, but not until after it had attacked three more people and a dog. Since the cat has been confirmed as rabid, and it is certainly possible that it may have bitten the jogger during the attack, there is a real risk to the unknown woman of developing rabies.
The potential for rabies exposure should be considered following any bite from a mammal. If the animal is acting strangely (attacking joggers would certainly qualify) and it's rabies vaccination status is unknown, the concern is much greater. It's important to identify any animal that has bitten someone so it can be evaluated to deterimine whether there is a risk of rabies. This would include examining the animal for clinical signs of rabies, and checking its vaccination status. Being vaccinated against rabies doesn't guarantee the animal doesn't have rabies, but it makes it very unlikely. Depending on the degree of risk and the status of the animal, observation of the animal in the home, strict quarantine, or euthanasia and testing might be indicated.
This jogger probably needs to be treated for rabies exposure, unless a bite can be completely ruled-out. This post-exposure prophylaxis (PEP) consists of an injection of anti-rabies antibodies, followed by 5 doses of rabies vaccine given over 28 days. It's not fun, but it's nothing like the old PEP method that people often hear about, which involved many more injections given in the abdomen. It's a small price to pay to avoid an almost invariably fatal disease.
More information about rabies can be found in our rabies archives and on the Worms&Germs Resources page.
Rat bite fever
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.
More information about the care of bites can be found in our bites archives and on the Cat Bites information sheet on the Worms&Germs Resources page.
Lungworms in dogs: Parasite risk or marketing ploy?
I read a press release today entitled "New Parasite Infection Killing Pet Dogs in Southern England". It's about the lungworm Angiostrongylus vasorum. The main reservoir for this parasite in England is the common red fox. Slugs and snails are involved in transmission of the worm as well. Infection of dogs most likely occurs through ingestion of the parasite from contaminated water or other environmental sources. The press release mentions a study that was released last year which reported an increase in the parasite in wild foxes. It mentions (without providing any data) that infections are occurring regularly dogs in some regions. This may well be true but brings to mind an important point I mentioned the other day (among others): know the source of information you are reading. I know I'm being a bit cynical, and it's possible that they have the well being of pets in mind, but the press release is from an online veterinary pharmacy, a company that obviously benefits from increased treatment of pets with dewormers.
This is made clear by their statement "Luckily there are a number of medicines available that can provide real and lasting protection from this nasty parasite. At www.vetscriptions.co.uk we recommend that all dog owners make it their business to find out about this disease and make sure that their dogs are fully protected."
Is lungworm a real and increasing threat in the UK? It's certainly possible. I don't dismiss the possibility at all.
Would I get concerned about it at this point? No. I'd look for objective information and ask my vet if there are any concerns in my particular area. Like the press release says, people should "make it their business to find out about this disease."
So what does this tell me? It reminds me that there are a lot of potential infectious disease threats out there that I need to pay attention to, but there are also a lot of people trying to make money at the same time. It could be that this company is being benevolent and honestly trying to make sure that pet owners are aware of the risks of lungworm. It's also possible they are taking advantage of a marginally relevant problem. Information like this is good for raising some questions, but getting advice from a non-biased source is critical.
European bat lyssavirus in cats
Some areas of the world are fortunate enough to be rabies-free. However, there's a closely related virus that is of concern in many of these areas: European bat lyssavirus (EBLV). This virus is present in bats in various countries and can occasionally be transmitted to other animals. A recent report in the journal Emerging Infectious Diseases describes EBLV infection in two cats in France. Both cats died, although the actual cause of death of one of them was uncertain (the animal was also infected with feline immunodeficiency virus (FIV)).
Infection with EBLV in domestic animals is very rare. The risk to dogs and cats is probably very low, but obviously not zero. Avoiding contact with bats is always a good idea. Even in rabies-free areas, measures should be undertaken to keep bats out of houses, and people or animals should never touch sick or injured bats.
The risk to humans from infected domestic animals is unclear. It is thought that dogs and cats pose little risk for further transmission. While susceptible to infection, they are unlikely to transmit EBLV, probably because they produce very low levels of virus. Although there are no clear data about using standard rabies prophylaxis for the prevention of EBLV, it is believed that it would be effective if the virus was transmitted from an infected animal to a person. One cat in this report bit a veterinarian, who received a rabies vaccine booster since he/she had previously been vaccinated against rabies. Fifteen people who were exposed to the second cat underwent the recommended rabies post-exposure series of shots as a precaution.
Even in rabies-free areas, bites from bats or other wild animals should be taken seriously. They should immediately be cleaned thoroughly with lots of soap and water, and medical attention should be sought.
A big problem with EBLV is that it can be very difficult to diagnose. In this Emerging Infectious Disease report, several different tests were used and results were inconsistent. Multiple tests are probably needed to make a diagnosis. It's possible, therefore, that without this kind of comprehensive testing cases could be missed.
Overall, EBLV is a minor concern for public health, but is yet another reason to just use common sense - avoid contact with bats and treat bite wounds carefully, even in rabies-free areas.
More information about rabies can be found on the Worms & Germs Resources page, and in our rabies archives.
Deworming kittens and puppies
Deworming adult cats and dogs is a rather controversial area at the moment. Balancing concerns about animal health, zoonotic disease transmission, drug resistance, compliance and cost is difficult. Risks vary between different regions/climates and there are no clear answers. One area that is much less controversial is deworming of kittens and puppies (less than 6 months of age), as there is general consensus that aggressive deworming is needed in these animals.This is because young animals are much more likely to harbour parasites. They are also more likely to contaminate the household environment during the litter/house training process and tend to have very close contact with people. The greatest concern tends to be about roundworms, since they are very common in dogs and cats (especially young ones) and zoonotic infections can occur (i.e. visceral and ocular larval migrans, similar to that caused by the raccoon roundworm, Baylisascaris procyonis).
Standard deworming guidelines are:
- Puppies should be dewormed at 2, 4, 6 and 8 weeks of age, then monthly until 6 months.
- Kittens should be dewormed at 3, 5, 7 and 9 weeks of age, then monthly until 6 months.
Further treatments depend on various factors, including the animal's lifestyle (risk of exposure), how common different parasites are in the region and perhaps whether there are high-risk people in the household. Your veterinarian can provide the best advice for your individual pet.
Another thing to remember is that not all parasites are killed by all dewormers. Specific deworming programs need to be set up to address different parasite risks.
More information about roundworms (and other parasites) in dogs and cats can be found on the website of the Companion Animal Parasite Council, an industry-funded organization.
Photo: A large mass of roundworms from the intestine of a heavily infected animal.
New York Times and Pet Health Advice: Bad Combination
I used the think the New York Times was a reputable newspaper and source of reasonable information. However, considering some of the articles I've seen, I no longer have a good opinion of this newspaper. One example from a few years ago came across my desk recently. The article is basically an infomercial for an unqualified person that sells pet health products. The person in question is an industrial designer by training - you'd think a reasonable news source would look for someone with training in veterinary medicine, nutrition or pharmacology when discussing pet health. (Given the level of expertise they require, I guess I'm qualified to comment in the New York Times about how to solve conflict in the Middle East or fix the economy). Among some of the gems in this article are:
- People "have to include raw and whole foods in their pets' diets..." and "[Pets] don't get E. coli or Salmonella." Tell that to the dogs and cats that get sick and die from Salmonella. I can't believe people that sell raw foods continue to falsely claim that pets can't get Salmonella. Outbreaks of salmonellosis associated with raw foods have been reported. Dogs have even been sickened in the recent peanut butter Salmonella outbreak.
- The big problem with the pet food industry is that people treat pets like televisions and get a new one if they're sick. Apart from the last part being ludicrous, what does that have to do with the pet food industry?
- The alley dogs this guy grew up with in the Bronx lived a long time. Now, a dog is considered old if it lives past 7 years. Show me any evidence that feral dogs live longer than household pets. Not a chance.
- Pets are dying younger because of low grade nutrition and pharmaceuticals. Again, show me evidence that pets are living shorter lives. I'm certain it's the exact opposite.
People need to make sure that they critically assess things that they read about pet health and diseases. Just because something is written in a high profile newspaper doesn't mean it's necessarily correct. In the internet era, volume overload and differentiating good sources from bad sources can be difficult. Here are some tips:
- Look for advice from qualified individuals. That's not a guarantee, but I'd rather have my car fixed by a mechanic than a gardener.
- Beware of advice from people that are in a conflict of interest, such as people selling a product. For most reputable companies, representatives can be sources of good information, but unfortunately it's not always true.
- Ask your veterinarian about questions relating to animal health and nutrition.
- Use common sense. If something seems too good to be true, it probably isn't. Something that claims to cure all that ails you probably cures nothing.
Cheap rabies vaccine clinics... good vs bad
Rabies clinics are common in some areas. They are typically one or two day events where people can get their pets vaccinated against rabies at very low cost. The good aspect of these clinics is that some animals that get vaccinated there would not otherwise be vaccinated. The downside of rabies clinics is that they are not the same thing as a normal vaccine appointment with a veterinarian. Rabies clinics are usually "assembly line" vaccination - the goal is to get as many animals vaccinated as quickly and efficiently as possible. The animals are not given a physical examination and there is no discussion with owners about preventive medicine or other problems. Therefore, there is no opportunity to detect and address other health problems, which is (in my opinion) the most important aspect of routine vaccination appointments. There is also no opportunity for vaccination against other important diseases.
Rabies vaccine clinics can be beneficial in situations where some people are unable (or, unfortunately, unwilling) to pay for a normal veterinary examination and complete vaccination. Anything that increases the number of animals vaccinated against this devastating disease is useful. However, rabies clinics also can compromise the health of animals (and potentially their owners) if they are the only routine veterinary contact. They can also end up hurting owners financially in situations where early disease would have been detected and addressed during a regular vaccine appointment. Often, diseases are much more difficult and expensive to treat when they are identified later.
So, while it's obviously tempting to take the cheapest option available, if you can afford a regular veterinary appointment, don't use rabies vaccine clinics. It will be better for your pet and for you to have a regular vaccination appointment with a good physical examination and full consultation.
More information on rabies can be found on the Worms & Germs Resources page.
Plague isn't back... It never went away
Plague (aka the "black death") is a fascinating disease. It is one of the most important diseases in human history because it had a devastating impact of the human population during various outbreaks. Many people may not realize it, but plague is not just a historical problem - it is still alive and well in some areas of the world. Plague is caused by the bacterium Yersinia pestis, which tends to circulate in rodent populations and can be spread by fleas. In North America, plague is most common in some regions of the southwestern US, particularly New Mexico, Arizona and Colorado. We're heading into the high-risk season for plague in those areas: March to October.
Plague can infect domestic pets, and pets can be a source of human infection. Cats are quite susceptible to plague, whereas dogs are quite resistant. Cats can transmit plague to people. Pneumonic plague (infection of the lungs with Y. pestis, not to be confused with bubonic plague which is primarily infection of the lymph nodes with Y. pestis (see picture left)) in cats is of particular concern, because in this form the bacterium can be spread through the air over short distances.
Prairie dogs (which some people keep as pets) are also very susceptible to plague.
A paper in Clinical Infectious Diseases a few years ago (Gage et al, 2000) described 23 cat-associated cases of plague in people, five of which were fatal. People were infected by face-to-face contact, bites, scratches or simply caring for an infected cat. Most affected people were cat owners, but some were veterinary clinic personnel. Plague is treatable with antibiotics, but the disease can progress rapidly, so it's important to determine the diagnosis and start treatment as soon as possible.
Here are some things to consider if you live in an area where plague exists:
- Keep pets indoors as much as possible to help prevent exposure to infected wildlife.
- Use routine flea control measures as directed by your veterinarian.
- Consider any cat that develops a fever of unknown origin or enlarged lymph nodes a plague suspect.
- Don't let cats and dogs hunt wild rodents, and don't let them have access to rodent burrows.
- If your pet has been diagnosed with plague, you need to seek medical attention promptly in case you have been exposed. If a person in the household is diagnosed with plague, pets should be investigated as possible sources and should be treated prophylactically in case they have been exposed.
Lower photo: Bubo in the leg of a person infected with bubonic plague (source: Centers for Disease Control and Prevention)
Rabies survival: good news, but don't get too excited
Until a few years ago, rabies was described as "invariably fatal" in people. A case of rabies in a 15-year-old girl in Wisconsin a few years ago changed that. She managed to survive this deadly disease due to a very aggressive treatment protocol, that was subsequently named the Milwaukee Protocol. This led people to call start calling rabies "almost invariably fatal". Unfortunately, subsequent attempts to treat people with this protocol failed, and there has been some debate about whether the treatment was really effective - rabies virus was never actually isolated from the first survivor, and some have speculated that the girl was in fact infected with "defective" virus that was less virulent. The patient also developed a very high antibody level against rabies virus, and this abnormally profound immune response to the infection may have also played a role in her survival. Regardless, the failure of anyone to report similar success using the Wisconsin Protocol dampened optimism about this treatment.
That was until a recent case from Brazil, where another successful treatment was reported in a 12-year-old boy who was apparently infected with rabies. He was recently released from the critical care unit, but still has some neurological problems as a result of his ordeal.
It’s heartening that there has been another survivor of this dreadful disease, but I think we still need to consider rabies "almost invariably fatal". We can't afford to relax one bit about the severity of this disease. It is likely that only a very small percentage of people treated with this protocol will survive, and even fewer (if any) will recover fully. Survival likely depends on very aggressive treatment started very early in disease, as well as a host of other factors such as a strong immune response by the patient and, probably, a lot of luck. Prevention of this disease remains, by far, the best protection for both people and animals.
More information on rabies can be found in our Rabies archives and on the Worms & Germs Resources page.
Cats and pregnancy: Not-so-"expert" advice
A recent column by pediatrician Dr. T. Berry Brazelton has caused quite a stir. Dr. Brazleton is apparently a very well known syndicated columnist, and he answered a question from a reader about her pregnant daughter and her cats. The reader was concerned about the cats lying on the baby. However, Dr. Brazleton focused on the risks of toxoplasmosis, which we've covered in previous posts and in a fact sheet in the Worms & Germs Resources page. He points out some valid facts and concerns regarding toxoplasmosis and prevention of this disease. However, he strayed off the logical, evidence-based trail with the statement "It would be better for the baby if your daughter would rid herself of the cats."
I am unaware of any medical, veterinary or public health group that advocates removal of pets from households with pregnant women. In fact, the Centers for Disease Control and Prevention (CDC) specifically state that pregnant women do NOT need to get rid of their cats. Dr. Brazleton also stated "Some cats will seek out the infants' mouths and noses and lie on them to smother them." While Dr. Brazleton may be well-versed in pediatrics, he apparently didn't take the time to look into current evidence and recommendations in this regard. His statements are ill-informed and irresponsible.
One should never dismiss peoples' concerns about disease or injury to babies from pets. The health of babies far superceeds concerns about pets. However, there are positive social and emotional aspects of pet ownership that similarly must not be ignored. There is simply no evidence that removing cats from households with pregnant women or infants is useful or necessary. The key is to consider basic (often common sense) infection control measures and proper animal management/training to reduce the risk of any adverse events.
Pet columnists have picked this article up and made various responses. One of the best I've seen is from Steve Dale. It provides some good basic information about why Dr. Brazleton's advice is unsound.
Comprehensive information about toxoplasmosis, and reducing the risks of disease, can be found on the Worms & Gerns Resources page.
Image credit: http://homepages.cwi.nl/~steven/julian/choclet/choclet.html
Parvo in the park
A park in Orange County, Florida has been closed because a dog with canine parvovirus was found in the park. Canine parvovirus is a potentially serious infection in dogs (mainly puppies) that can cause severe vomiting and diarrhea. In some cases, it can be fatal. Proper vaccination against parvovirus is critical for puppies. In Orange County, they have closed the park because of concerns about parvovirus transmission. The have also apparently "bleached the dog park".
Parvovirus can live for a very long time in the environment, however disinfecting an outdoor environment is not only impractical, it's impossible! We can disinfect clean, smooth surfaces like sealed ceramic floors and smooth countertops, but we can't disinfect outdoor environments with permeable, porous surfaces and abundant organic debris (dirt). Bleach is not active in the presence of organic debris, and porous surfaces allow bacteria and viruses to escape contact with disinfectants. So, while it's good to see that they are concerned about disease transmission, this particular aspect of their control efforts isn't going to be effective.
Parvovirus exposure is an ever-present risk in areas where multiple dogs congregate. The virus can be shed in the stool of even healthy-looking dogs. In this situation (like all others) the emphasis should be on keeping high-risk dogs (e.g. unvaccinated puppies) out of these areas, not closing the park altogether and attempting to disinfect it. Parvovirus vaccination is very effective, and properly vaccinated adult dogs are quite low risk. Prompt removal of stool by dog owners helps reduce the risk further by decreasing the risk of environmental contamination. Therefore, the three most important control measures are:
- Ensure puppies are properly vaccinated.
- Keep puppies out of areas visited by numerous dogs until they have been fully vaccinated.
- Scoop poop.
And since the focus of this site is zoonotic diseases, remember that canine parvovirus is not transmissible to people. Human parvovirus infection (Fifth disease) is caused by a completely different virus.
Baby accidents and dog baths
Recently I was having a discussion with a reporter about cleaning and disinfection, and the reported mentioned that her child had pooped in the bathtub the other day. My response was "mine too", since coincidentally, my 17-month-old daughter did the same thing on the same day. We discussed about what to do with the bathtub, and it lead me to thinking about issues regarding bathing pets in bathtubs.
I'm not sure I've ever given my dog a bath in the bathtub, but some people do. I've never seen any recommendations about infection control practices associated with dog-washing or an assessment of the possible risks involved. Since there are lots of bacteria that live on or in pets (and people), and some of these can cause disease in certain situations, it's something worth considering. Overall, the risks from a healthy pet in a household full of healthy people are probably exceedingly low. There are, however some situations where risks might be higher.
Pet factors that may increase the risk of disease transmission to people if they bathe in the same tub include:
- Diarrhea
- Wounds or skin infection
- Contamination of the hair coat with feces
- Young puppies or kittens, since they are more likely to be carrying certain infectious bacteria or parasites
People that are probably at higher risk of infection if they use the same tub as a pet include those who:
- Have open skin lesions/wounds or chronic skin disease
- Are immunocompromised
- Are very young or very old
- Are pregnant
It's probably best to avoid bathing pets in the bathtub (and certainly don't bathe them in the kitchen sink!!), if possible. Bathing pets outside or in the laundry room sink are better ideas, although they're not always practical. If you are going to bath your pet in the bathtub, here's what I'd recommend:
- Ensure the pet is healthy.
- Remove items from the area around the tub that might become contaminated (e.g. wash cloths, shampoo bottles, kids' bath toys).
- After the bath, use soap and water to clean the tub, walls and other areas that may have been splashed.
- Rinse all surfaces thoroughly with hot water.
- Allow all surfaces to dry completely.
I'm not sure a disinfectant is really needed in most cases, but it probably wouldn't hurt. If used, a disinfectant (like diluted household bleach) could be sprayed or wiped onto surfaces after cleaning. It should be allowed to sit for at least 15 minutes. Immediately wiping off the disinfectant greatly decreases the chance of it having any effect.
If you have a high risk pet or high risk person in the household, I'd be very careful. The best thing would be to bathe the pet elsewhere, either outside or take it to a at a vet clinic or pet groomer. If you do bathe your animal in the tub in this situation, be especially thorough about cleaning the tub afterwards, and definitely apply a disinfectant.
Group B Streptococcus: Don't blame the dog
I received the following question from a reader the other day: "I'm currently pregnant and was bitten by my grandmother's German Shepherd. The bite was on my ankle and broke the skin in several places. I went to the doctor and was prescribed antibiotics and the wound has seemed to heal fine. This is my second pregnancy and I have been diagnosed as group B strep positive, which I wasn't with my first child. I know that dogs can't spread strep throat to humans, but is it possible that I picked up group B strep from the bite?"
The short answer is that it's extremely unlikely there's an association.
Group B Streptococcus is predominantly a problem in people. Most people that carry this bacterium have no problems, although it can cause infections in some situations. It is of particular concern in pregnant women, because in 1-2% of exposed newborn babies the bacterium can cause serious infections such as bloodstream infections, meningitis and pneumonia. That is why pregnant women are often screened for Group B Streptococcus shortly before their due date, by taking a swab from the vagina and rectum. Approximately 10-30% of pregnant women carry Group B Streptococcus. Pregnant women that are carriers are usually given antibiotics shortly before delivery to reduce the risk of infection of the baby.
What about the role of pets? Group B Streptococcus is mainly found in people, and is quite common in healthy people. It is rare in pets, although it can cause various types of infections in animals too. Group B Streptococcus infections in dogs might actually represent human-to-dog transmission, although this hasn't been proven. In the case described above, a dog bite on a person's leg would not be a high risk for transmitting this bacterium to the intestinal tract or vagina. If a dog was carrying this bacterium in its mouth, it could cause a bite wound infection, but it is very unlikely that the bacterium would spread to other parts of the body in a healthy person. Other bacteria in the dog's mouth would be more likely to infect such a wound, even if Group B Streptococcus was present. If dogs were common carriers of this bacterium (which they are not), the main risk of transmission would be from regular contact, not bites.
So don't blame the dog... at least not for the Group B Streptococcus. The bite itself is another issue.
Why not to feed puppies human breast milk (in case you needed a reason)
I came across an interesting (and somewhat bizarre) paper in the journal The Lancet from 1988. It described a case of listeriosis in a baby. Listeriosis is caused by the bacterium Listeria monocytogenes. Human infections are usually acquired from eating contaminated food. I made some comments about the risk of listeriosis to household pets in an earlier post during the recent foodborne outbreak of listeriosis in Canada that was associated with contaminated meat
The paper from 1988 puts a "new spin" on potential sources of infection for pets.
The baby described in the report was not breastfed for the first three days of life because her mother had some post-delivery complications. The surplus milk that was collected over those three days was reportedly fed to a litter of Doberman puppies. All three puppies in the litter became sick the day after the child began showing signs of illness. Listeriosis was diagnosed in both the baby and the puppies. Listeria monocytogenes was cultured from the mother's milk. Apparently the baby and the puppies were all infected by drinking the mother's milk. The baby, and two of the three puppies, survived.
Certainly, human-associated listeriosis in pets is extremely rare, and (presumably) so is feeding puppies human milk. This case just shows how infectious diseases can do strange things, and that diseases can move between people and animals in both directions. It also highlights that knowing the health status of both animals and people is important for physicians and veterinarians to make informed decisions about diagnosis and treatment of some diseases.
Hatching chicks in classrooms
My oldest daughter is in Grade 2, and last year her class hatched chicken eggs in the classroom. As a parent, I was somewhat torn about the idea. My main concern was the risk of exposure to Salmonella. A recent article in Morbidity and Mortality Weekly Reports described outbreaks of salmonellosis associated with contact with live poultry. Most cases were associated with handling baby chicks obtained from agricultural stores or by mail order. Infections from classroom and petting zoo-associated contacts were also reported.
Salmonella contamination of eggs and carriage by baby chicks is very common. The CDC recommends that children less than five years old do not have any contact with baby chicks, and that older individuals pay close attention to hygiene in order to prevent transmission of Salmonella. Being six years old, my daughter was just over this age cutoff (although there's nothing magical about going from five to six years old, so I'd still consider her at somewhat higher risk). So, as long as good infection control practices were used (e.g. hand hygiene), the risk to the children was probably quite low. Were the benefits of hatching eggs in the classroom worth the risk? I don't know, but she enjoyed the experience and did learn a few things along the way. Concerns about infectious diseases are often dismissed, which is a problem, but sometimes excessive concern gets in the way of life. There's rarely a clear answer as to what is acceptable and what is too risky, given the potential benefits.
- Eggs and chicks should not be kept in classrooms where children under five years old will be present, or if there are immunocompromised children in the class. It's unclear whether all teachers would know if they had a high-risk child in the class. Parents of immunocompromised children should make sure teachers know about their child's increased risk.
- It is prudent for teachers to send home a note to inform parents if eggs/chicks will be in the classroom, or if similar activities involving animals are undertaken.
- Eggs and chicks should be kept in a complete enclosure, in an area that is always supervised when children are around.
- Chicks should always be kept in their enclosure. They should never be taken to areas (e.g. a student's desk) where food might be consumed.
- Direct contact with eggs and chicks (and their environment) should be kept to a minimum.
- Hands should be thoroughly washed or an alcohol hand sanitizer used immediately after contact with eggs, chicks or their environment.
- Appropriate thought should go into the use of eggs and chicks in classrooms. They should be there for more than the "novelty factor". There should be a clear teaching plan associated with them so they provide the maximum educational value possible.
- Testing eggs and chicks for Salmonella isn't practical. A negative result cannot guarantee that Salmonella is not there. As well, there are other infectious diseases that are of concern. Consider all eggs and chicks Salmonella-positive and handle them appropriately.
Lambing season and Q fever
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I have a small flock of Soay sheep and lambing season started today (too early, but better than the -30C weather from a few days ago). For someone like me, lambing season inevitably triggers thoughts about Q fever, a zoonotic disease that is most commonly associated with contact with small ruminants like sheep and goats (especially sheep). The disease is caused by the bacterium Coxiella burnetii. This organism is highly infectious - very few bacteria are required to cause infection - and is considered a potential bioterrorism agent. Coxiella burnetii can be transmitted by direct contact with an infected animal, or by inhalation of organisms in dust or dirt that get blown into the air. It can be carried by healthy animals several species, but the greatest risk of transmission is from sheep and goats around the time of birthing (lambing and kidding, respectively). At that time, large numbers of C. burnetii can be shed with the placenta and fetal fluids, and can also be found on the newborn animals. Close contact with the animal and these tissues during lambing, such as with our first lambing this morning - a stillborn lamb that was stuck at the shoulders and required some manipulation to free it - can result in transmission of C. burnetii.
On a happier note, the second lambing in our flock was unassisted, although I still handled the little guy to make sure he was okay.
Q fever can affect people of any age or health status. Disease can range from mild to life-threatening. More information on Q fever can be found on the websites of the Ontario Ministry of Health and Long-Term Care and the Centers for Disease Control and Prevention (CDC), as well as the previous Worms & Germs post entitled "Q Fever - From Goats to People (and Pets!)". The disease can cause miscarriage in pregnant women. People with heart valve disease or vascular grafts are also at high risk for serious disease from this infection.
- It is prudent to consider all sheep and goats Q fever-positive unless proven otherwise (which is difficult to do).
- Contact with newborn lambs and kids, placentae and fetal fluids of sheep and goats, and any area contaminated by these tissues should be avoided as much as possible. If contact is necessary, it should be done by low-risk people, and careful attention should be paid to hygiene, especially handwashing.
- Pregnant sheep and goats should not be used in petting zoos. Unfortunately, this is actually a common occurence.
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- Live birthing exhibits, where sheep or goats give birth in public during fairs or similar events, should not be held. If they are held, they should be in an area where there is no direct or indirect contact with the public, unlike this picture (right).
- While we focus on sheep and goats, many different species can shed Coxiella burnetii, including cattle and cats. It is reasonable to consider all animals a risk around the time of giving birth, and ensure that hygiene practices are optimal.
- At my place, Q fever control consists mainly of careful attention to hygiene around newborn lambs and their ewes, and not allowing my kids to handle newborn lambs.
- Like most zoonotic diseases, hand hygiene is a critical infection control measure.
Avoiding surgical site infections: No quick & dirty
One of my favourite stories about surgeons comes from a book by Irwin W. Sherman called "The Power of Plagues." In the pre-anesthesia and pre-antibiotic era, speed was considered the sign of a good surgeon. One surgeon, Robert Liston, was particularly renowned for his speed. However, speed sometimes lead to problems. In one surgery, he amputated a leg in 2.5 minutes, but the patient died of infection after surgery (a common event those days). During surgery, he accidentally amputated the finger of his assistant as well, who also subsequently died of infection. To top it off, he slashed the coattails of a surgeon who was watching, who "died of fright" thinking his organs had been slashed too. He's the only surgeon on record with a 300% mortality rate for a surgery.
These days, surgery is a lot more humane and safe. However, problems like surgical site infections still occur. They occur following a much smaller percentage of surgeries than they used to, but they can still be very serious. Nowadays, more of these infections are being caused by multidrug resistant bacteria, which can affect and be transmitted between both animals and people. It's been stated that the time of maximal influence on surgical site infections beings and ends in the operating room (e.g. the most critical time for preventing infection is during the surgery itself). However, there are things that can be done at home to help reduce the risk of infection.
- Antibiotics are usually NOT required after surgery, depending on what procedure was performed. But, if antibiotics are prescribed by your veterinarian, make sure you give the full course and follow all instructions carefully.
- Keep your pet from licking the surgery site. Trauma from licking and chewing, and bacteria from the mouth can help start an infection. If your pet is licking or chewing its surgery site, consult with your vet about ways to stop this.
- Keep an eye on the surgery site. If you see signs of infection such as excess heat, pain, redness, swelling or discharge from the site, talk to your vet as soon as possible.
- Don't touch the surgery site. You could contaminate the site with bacteria from your skin that could start an infection. Also, if an infection is present, bacteria could spread to you. If you must touch the surgical site (e.g. if you need to change the bandage over it, or your veterinarian has instructed you to clean the site), you should wear disposable gloves.
Dog infection linked to peanut butter Salmonella outbreak
Maybe the only thing surprising about this is that it's taken this long, but there has now been a dog infection reported in association with the massive peanut butter recall due to Salmonella contamination. This outbreak has made hundreds of people sick, and caused a few deaths so far. Pets that eat contaminated "people food" or pet treats are also at risk. So, it's not too surprising that an infection in a pet has now been reported (and reported cases are usually just the tip of the iceberg).
The case reported involves a dog in Oregon that was diagnosed with salmonellosis after being fed Happy Tails dog biscuits. The Salmonella strain recovered from the dog, who had severe diarrhea, was from the same serogroup as the strain involved in the peanut product outbreak. The product (Happy Tails Multi-Flavor dog biscuits, UPC 41163 42403, 4 lb box, “best by” date Oct 31 09) was tested at IEH Laboratories & Consulting Group in Lake Forest Park, WA and Salmonella was identified. Other products from this and several other companies have been recalled, so pet owners should check the products against recall lists. If in doubt, do not feed your pet(s) any treats until their safety can be verified.
Salmonella can cause disease in dogs ranging from mild diarrhea to severe bloody diarrhea and bloodstream infection that can be fatal in some cases. Dogs with salmonellosis can also transmit the infection to people, because they can shed large numbers of Salmonella in their stool.
If pets have been fed potentially contaminated peanut butter or treats, they should be watched carefully for signs of diarrhea, lack of appetite or decreased activity, and taken to a veterinarian promptly if there are any concerns. There is no indication to test or treat healthy pets that have potentially been exposed. Even if stool samples were tested and Salmonella was found, treatment of healthy animals would not be recommended. As always, careful handling of stool and frequent handwashing are key factors for preventing transmission of disease to people.
E. coli O157 outbreak tentatively linked to livestock show
An outbreak of E. coli O157 - the particularly nasty strain of E. coli that can cause hemolytic uremia (a serious kidney disease) and death - has been identified in Colorado, and signs are pointing toward a livestock show as the source. So far, 20 people have been identified as infected, including 19 children. The exact source of the infection is not clear, and could be food, water or contact with animals. However, considering the high percentage of children, the petting zoo is a likely source.
As we've discussed previously, petting zoos can be fun and educational events (particularly for children) but are always associated with some degree of infectious disease risk. Petting zoos are often poorly equipped to handle these risks, as we reported in a paper in Clinical Infectious Diseases a little while ago. Petting zoos are a risk because animals that appear healthy can still carry infectious diseases. This is particularly true for E. coli O157, which can be carried by perfectly healthy cattle. Despite the possibility of exposure to E. coli and other potentially harmful microorganisms, the potential for disease can be greatly reduced with some very basic measures, like handwashing, not eating in the petting zoo, handwashing, keeping baby bottles and other items out of the petting zoo, handwashing, and having signs encouraging people to wash their hands. The people in charge of this event stated that they had a well organized petting zoo with handwashing stations available, and that may very well be true. Having access to handwashing facilities is a critical step, but it doesn't do anything if people don't use them. Unfortunately, poor compliance with handwashing is very common and is one of the weakest links in infection control at petting zoos.
- Always wash your hands after leaving a petting zoo.
- Don't eat in a petting zoo area.
- Don't take items into the petting zoo that will go into a child's mouth, like bottles, cups and soothers.
Testing for ringworm with toothbrushes
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.
More information about ringworm is now available on the Worms&Germs Resources page, and in our archives.
Immunocompromised people and pets: testing for Bartonella
I did a presentation at a conference last week with a physician on the topic of "Pets and Immunocompromised Owners". It led to some interesting discussion. People with suboptimal immune systems are becoming more common in households and they often own pets. These individuals are susceptible to infections caused by microorganisms that would not typically cause disease in healthy people, and they are also more susceptible to severe (including fatal) disease caused by microorganisms that would only otherwise cause mild disease. Therefore, there's a lot of concern about pets transmitting infection to immunocompromised people. Rarely is removal of pets from households of immunocompromised people necessary, but precautions should be taken to reduce the risks of disease transmission.
One topic that comes up periodically is testing for Bartonella henselae. This bacterium is the cause of cat scratch disease, which is spread by cats through scratches (obviously) but also through bites and by fleas. Cats that carry Bartonella henselae hardly ever have any signs of disease. In healthy people, cat scratch disease typically causes fever, local lymph node swelling, headache and fatigue. Immunocompromised people, particularly people with HIV/AIDS, are at higher risk for severe disease, which can be fatal if it is not identified and treated promptly. Similar disease can also be caused by other species of Bartonella that are not carried by cats.
Tests for Bartonella are not 100% accurate. Some tests just indicate exposure which does not tell you whether the cat is still carrying Bartonella or if it was previously exposed but already eliminated the bacterium from its body. False negative tests (e.g. the cat has been exposed but the test comes back negative anyway) can also occur. When considering screening tests, or any diagnostic tests in general, only do a test if there's a reasonable chance that the results will affect what you do.
- If a cat is positive, I wouldn't recommend removing it from the house. It may or may not be shedding Bartonella, so the key points for avoiding cat scratch disease are reducing the risk of bites and scratches, and controlling fleas.
- If a cat is negative, it's probably (but not guaranteed to be) free of Bartonella, but it could be infected later in life, and the key points for avoiding cat scratch disease are reducing the risk of bites and scratches, and controlling fleas.
So, if the recommendations are exactly the same in both cases, save your money and spare the cat the blood sample. I don't recommend testing for Bartonella henselae. The Infectious Disease Society of America also does not recommend testing (or treating) cats for Bartonella in their guidelines for HIV/AIDS patients.
Buyer Beware - Scrutinizing New Products
This post originally appeared on www.equIDblog.com, the sister site of Worms&Germs that covers topics on equine infectious diseases, on February 3, 2009.
New animal health products are released on a daily basis. A great deal of time, effort and money is usually spent to market these products - sometimes more than was put into developing them. As a consumer, it's important to think before you buy, especially with new products. Take a moment to consider whether a product is right for your animal, and whether the product's intended use and claims are reasonable. The biggest problems tend to occur with "alternative" or non-traditional products, which encompass a huge range of products that are aggressively marketed, with little to no research or testing to back them up. Here are some specific points to think about:
- Ask for research proving that the product works. "Data on file", anecdotes and other non-scientific sources are not adequate. Demand published research in peer-reviewed scientific journals. That means that the research has been independently scrutinized. Published data are not a guarantee that something will work, because some journals are not very strong and may publish weak research, but the lack published research altogether may indicate that research was not done, was not done right, or showed no benefit to using the product. Regardless of the type of product, there is no reason why proper research cannot be done to prove it is beneficial if it actually works.
- When looking at promotional literature, read it with a bit of skepticism. Think about whether or not what they say makes sense. A good general rule that I have is something that claims to cure all that ails you, probably cures nothing.
- If promotional materials do talk about research, check if they did a proper statistical analysis to really show that the product is better than the alternative. Showing a difference in numbers between two groups really mean nothing without proper analysis. For example, you could flip a coin 10 times and get 6 heads and 4 tails. Someone else may flip the coin 10 times and get 5 head and 5 tails. Clearly there's a difference in the numbers, but does it mean there's a difference in the ability of the two people to toss a head or a tail? Absolutely not.
- Don't get taken in by endorsements from "big names". More often than not, they're being paid for the promotion.
- Consult your veterinarian about new products. Be aware, however, that bad science is often marketed to vets as well and your veterinarian needs to be equally diligent.
At the end of the day, it's still "buyer beware". However, thinking about these basic points may help weed-out some particularly poor products. Additionally, and more importantly, increasing demands by consumers to see solid supportive research may be the only way to get companies to actually invest in testing and research to make sure their products work.
Rabies on vacation: Pack some common sense
A few years ago, a tour agent in a Caribbean country tried to convince me that taking my young children in an open-sided vehicle on a drive over the country's highways was perfectly safe. My response was that the laws of physics don't go on vacation when I do - meaning that a car accident with unrestrained children is a bad thing even on a nice sunny island. The same concept goes for infectious diseases: when on vacation, you should try to leave your worries behind, but not your common sense. Travel-acquired diseases are extremely common. Transient, annoying, but usually self-limiting problems like food poisoning affect thousands of people on vacation, but more serious diseases can also be encountered.
A recent rabies outbreak in dogs in Bali highlights some of these concerns. Rabies is common in stray/feral dogs in many countries, and there can be huge dog populations in some common tourist areas. It's human nature for many people to want to feed or pet these strays. However, people often forget about the potential for rabies exposure. An additional concern is that proper post-exposure treatment for rabies may not be readily accessible in many countries. Some countries are mounting aggressive vaccination programs of strays in response to the risk to local inhabitants and tourists, but people need to be aware that the risk exists and can be very significant. It has been reported that 23 people from Britain have died of rabies acquired abroad since 1946. That's not a huge number, but it's not good if you are one of those 23, and such tragedies are preventable.
Remember these simple points when you are on vacation:
- Stay away from strays (dogs or cats).
- Report dogs that are acting strangely to local authorities or someone else that might be able to help (such as a hotel concierge).
- If you are bitten, take it seriously. If you cannot identify the dog, confirm its rabies vaccination status and ensure that it is properly quarantined, you should probably be considered exposed to rabies. If that is the case, get post-exposure treatment as soon as possible.
- If you are going to have contact with stray dogs or wild mammals during your vacation, such as volunteering with animal care groups, get vaccinated against rabies before you go.
- Always remember to pack some common sense.
Stupid things done with snakes
A Las Vegas woman reportedly agreed to babysit a friend's pet python. She brought the 18-foot snake into her house, where her three-year-old son also lived. Bad move, for many reasons. At one point, the woman returned from the bathroom to find the snake wrapped around her son, who was turning blue. The mother stabbed the snake 17 times before it released the child.
Large snakes can be dangerous, particularly to young children. Without proper (escape proof) enclosures and people who know how to handle them (and some common sense), there is a real risk of injury or death, as was clearly demonstrated here. Also, reptiles of all kinds (including snakes) are prime sources of Salmonella infection. Allowing reptiles to roam the house and/or have direct or indirect contact with young children is an unnecessary risk. Various groups have stated that reptiles are not appropriate pets for children less than five years of age, nor for people with weakened immune systems, primarily because of the risks of Salmonella.
Hopefully the child in this terrifying case is alright, although he was also bitten, which can lead to complications of its own. The snake had to be euthanized because of the stab wounds. So, we have an injured child and a dead snake resulting from the stupidity of a couple of adults who didn't apparently see a problem with leaving a large predatory carnivore free in the same location as a prey-sized child. Authorities are still deciding whether to charge the mother with child endangerment.
