The most common (but still quite rare) disease that can be transmitted from fish to humans is infection with Mycobacterium marinum. This microorganism can be found in both freshwater and saltwater. It can cause skin infections, usually in areas where the skin is already broken, such as pre-existing scrapes and cuts, or skin that is damaged while cleaning an aquarium. Serious or long-term problems are rare in otherwise healthy people, but infection can be fatal in individuals with a weakened immune system.

Various other bacteria found on fish and in aquariums can cause infection in people as well. These are usually also "opportunistic infections" that tend to occur in people with weakened immune systems or infected wounds.

While fish are low risk pets, you can still minimize the risks that do exist by following a few simple precautions:

• Wash your hands after contact with aquarium water or items in the aquarium. Gloves should be worn to prevent skin damage if you need to touch rough or sharp surfaces.
• Do not clean an aquarium in the kitchen.
• Do not dump aquarium water down the kitchen sink.
• Prevent contact of aquarium water or contents with open wounds on your skin.
• Keep aquariums covered. This helps keep other pets (e.g. cats) from drinking or playing in the water. (It also prevents escape attempts by the fish, which never end well!)

The latest bizarre example of stupid things done with bats occurred in Montana, where a parent brought a dead bat to a school and let young children (kindergarten and grade 5 students) touch it. Touching a bat in itself is a bad idea, let alone touching one that has died of unknown causes and encouraging kids to touch it. The teachers apparently had no objections to this activity. The parent who brought the bat had the students use an alcohol hand sanitizer after touching the creature, but it is still very irresponsible for someone to encourage children to touch a high-risk animal, regardless of what is done after. I'm sure the parents of the children didn't know beforehand, and certainly some were no doubt very upset when they found out about the incident (or livid would be a better description, if it was my kids that were involved). School officials did not find out about the dead bat until after its little visit, at which time the local and state public health authorities were contacted. The bat was tested and was positive for rabies.

Overall, the risk of rabies transmission is probably low in this case, but not zero.  It has therefore been recommended that the 80 students that may have touched the bat be given post-exposure rabies shots, which may cost up to $800 per child!. Another ten children may have touched the bat at a soccer practice - for a dead bat, it sure covered a lot of ground!

• Never touch a bat, dead or alive.  Obviously, if you shouldn't touch a bat, you shouldn't encourage kids to do so either!
• Unstructured and unapproved contact with animals in classrooms should be prevented. Animals can be good educational tools, but only if student and animal health and welfare are properly addressed.

More information on Rabies is available on the Worms & Germs Resources page.

Most of the research about hand hygiene that has been published has focused on its use and impact in human hospitals, but this area is now also being studied more with regard to animals and veterinary medicine. A study published earlier this year in Veterinary Microbiology provided more evidence that hand hygiene is a critical infection control measure when dealing with animals. The study, coordinated by Dr. Maureen Anderson (of Worms&Germs fame) looked at MRSA carriage rate in veterinarians who work with horses. In addition to finding a high rate of MRSA carriage among these veterinarians (which was consistent with other reports indicating that equine vets are at higher than average risk for exposure to MRSA), the study looked at factors associated with MRSA carriage. Vets that reported routinely washing their hands between farms and those that reported washing their hands after contact with potentially infectious cases had a significantly lower rate of MRSA carriage. That should come as absolutely no surprise, but it's one more piece of evidence that we need to pay more attention to this routine infection control measure, in human hospitals, in veterinary environments and in households.

Remember, the 10 most important sources of infection are the fingers on your hands!

Click here for instructions on how to wash your hands properly.

• Animals that received fluoroquinolones were significantly more likely to develop an MRSA versus an MSSA infection.  Fluoroquinolones are a specific class of antibiotics that includes drugs such as enrofloxacin, orbifloxacin and marbofloxacin.
• In both groups (MRSA and MSSA), most of the infections were skin and ear infections, with no significant difference in types of infection between the groups.
• There was no difference in the proportion of animals that survived their infections between the two groups: in both groups, over 90% of the animals survived. However, it is important to bear in mind that the majority of the infections were skin and ear infections, which are not usually life-threatening.  Further study of more serious types of infection is needed to determine if MRSA is associated with a greater risk of death in dogs and cats.

This study provided more evidence that MRSA is an important problem in dogs and cats, and that the use of antibiotics is likely an important factor in the development of MRSA infections, compared to infections caused by MSSA. It also showed that the survival rate for common types of MRSA infections is high, if the infection is properly diagnosed and managed.  Hopefully the information provided by this study can be used in future studies to help evaluate more risk factors, and to identify things that can be done to reduce the impact of MRSA in dogs and cats.

More information about MRSA in pets can be found on the new MRSA information sheets posted on the Worms & Germs Resources page.

Picture: Gram stain of Staphylococcus aureus

A key part of rabies prevention, which is also a major focus of rabies education programs, is the need for vaccination of pets, even strictly indoor pets. Rabies vaccination is a cheap and effective way of protecting your pet, yourself and your family from this disease. It's also required by law in many areas.  The implications of rabies exposure of pets that are not properly vaccinated can be severe, possibly including euthanasia or very long quarantine, even if they are not infected.

Many groups are holding events to increase awareness about rabies, such as the People and Pets Walk to End Rabies which is being held by the University of Guelph. Information from an advertisement for this event states "Although rabies does not seem like an issue at home, it is a major health problem for both humans and animals in developing countries, claiming the life of one person every ten minutes.  If we work together, we can make a difference. Please show your support and join us at the walk to help make rabies history!" That statement should make it clear why we talk about rabies so much. One human death every 10 minutes is a startling figure for a disease which we should be able to control.

More information about rabies is available on the Worms & Germs Resources page.

Above: All reported disease outbreaks/cases worldwide in the last 30 days.
Below: Reported outbreaks/cases of Salmonella in North America in the last 30 days.
See the HealthMap site for more details.

The report comes as no surprise - turtles are actually relatively commonly implicated in cases of salmonellosis in people (although still not nearly as commonly as foodborne transmission). It's particularly a concern in children, because kids may have close contact with pet turtles and may be more susceptible to serious infection.

In response to the cases in Los Angeles, the county Department of Public Health emphasized that parents must be wary of buying turtles for their children. Even though the sale of small turtles (less than 4 inches long) was banned in the US over 30 years ago, unfortunately these animals are still widely available in many pet stores, flea markets, and from other sources. Los Angeles Public Health personnel reported that children were getting sick because they were kissing their pet turtles - something that is very risky and should never be done by anyone, especially children. If people have pet turtles, they must be very diligent to practice good hygiene to reduce the risk of transmission of Salmonella.

More information about the risks associated with pet turtles, and measures that should be taken by people who own turtles, is available on the Worms & Germs Resources page.
 

Treatment selection is further complicated by problems that can occur when methicillin-resistant staphylococci are tested against certain drugs in the lab - problems that are not readily apparent unless extra testing is done.  One "problem" drug is the antibiotic clindamycin. Clindamycin can be an effective treatment for MRSA or MRSP infections, but some MRSA strains may be resistant to it despite appearing to be susceptible based on normal laboratory testing. This is because the bacteria can have "inducible resistance".  Inducible resistance can be detected by a special test called a D-test (see picture), but this test is not widely performed in veterinary laboratories.

In recent study presented by Dr. Meredith Faires (University of Guelph) at a conference last week, 55% of MRSA from dogs and cats that were reported to be resistant to erythromycin and susceptible to clindamycin were actually inducibly resistant to clindamycin.  But no MRSA that were susceptible to erythromycin were inducibly resistant to clindamycin. In contrast, inducible resistance to clindamycin was not identified in any MRSP. Therefore, in the absence of specific testing for inducible resistance (i.e. a D-test), it is wise to consider all erythromycin resistant MRSA to be clindamycin resistant as well, regardless of the results of traditional antibiotic susceptibilty testing.

While commercial pet foods undergo rigourous quality control and are much less likely to contain potentially harmful bacteria such as Salmonella than, for example, raw meat diets, it is important to remember that situations such as this can happen. So it's still a good idea to wash your hands after handling pet food, of any kind.

• Only use meat that is suitable for human consumption. Don't buy 'adulterated' meat or meat labeled unfit for human consumption.
• Keep raw meat frozen until you need it. Only thaw out the portion that is need for the next feeding, and thaw the meat in a sealed container on the bottom shelf of a refrigerator.
• Handle raw meat with care. Do not allow it to contaminate kitchen surfaces or items that may come in contact with other food. Clean and disinfect any items that come into contact with raw meat.
• Wash your hands thoroughly after handing raw meat or anything that has touched raw meat (e.g. your dog's food bowl).
• If your pet does not finish all the meat fed right away, discard any uneaten raw meat promptly. Do not allow raw meat to sit in a bowl at room temperature. Some dangerous bacteria can multiply rapidly under these conditions.
• Regularly clean and disinfect your pet's food bowl, but bear in mind that  a recent study showed that it is very hard to eliminate Salmonella from raw meat in food bowls.
• Make sure your veterinarian knows that you feed raw meat. This is particularly important if your dog develops vomiting or diarrhea.
• It is very important to make sure that your pet's diet is well balanced, which can sometimes be difficult to do when feeding non-commercial or raw diets.  Read about raw meat feeding, and try to find good sources of information (which is not always easy) to reduce the risk of problems caused by feeding an unbalanced diet.
• Never feed raw meat to sick dogs, puppies or pregnant dogs.

A recent study in the journal Zoonoses and Public Health described the risks of therapy dogs shedding Salmonella and other potentially harmful bacteria. The authors tested 200 dogs over a 1 year period, 20% of which were fed raw meat as part of their normal diet. Dogs fed raw meat were 23 times more likely to shed Salmonella compared to other dogs. They were also 17 times as likely to be shedding extended spectrum beta-lactamase (ESBL) Escherichia coli (a highly drug-resistant form of E. coli). 

The study concluded that, because of the risk of Salmonella shedding and the high-risk nature of the patients and other people that therapy dogs interact with, dogs that are involved with hospital/patient visitation programs should not be fed raw meat.

What does this tell us about feeding raw meat to pets?

Although this study doesn't answer all of the questions about the risks of raw meat diets, it reinforces the fact that pets fed raw meat have significantly higher rates of shedding of potentially harmful bacterial such as Salmonella and antibiotic-resistant E. coli. Eating pig ear treats has also been associated with Salmonella shedding. However, there was no association between a dog being fed raw meat and the animal itself developing diarrhea. In fact, raw-fed dogs had a lower incidence of extra-intestinal infections (combination of eye, ear, skin and urinary tract infections).

In general, raw meat diets should be avoided. While adverse health effects were not reported in this study, disease (including deaths) from Salmonella has been reported in dogs in other studies. While the overall risk may be low, feeding raw meat is an avoidable risk. However, it would be inappropriate to completely ignore the finding that raw-fed dogs had lower rates of certain infections. It is possible that there can be health benefits from feeding raw meat in certain dogs, but the potential benefits must be weighed against the potential risks to the animals and people with which the has contact. Raw meat diets should never be fed to pets that have contact with immunocompromised people (in the household or as part of visitation program), infants or the elderly.

If you are going to feed raw meat to your pet, make sure you take precautions to reduce the risk of infecting yourself or someone else. We'll post more on that aspect soon.

Overall, the infectious disease risks associated with having "Rover" in a restaurant should be very low. Dogs don’t emit some intangible "aura of infection," so just having them in the vicinity while people are eating is not a problem.  Microorganisms have to make it from the dog’s body to a person (and usually into their mouth) to cause disease. We don’t have many concerns about airborne spread of diseases from dogs to people.  In reality, simply having a dog in a restaurant should be less risk than having people in the restaurant (since people can transmit some infections to each other over short distances by coughing and sneezing).  But for this to be true, people still have to handle their dogs properly, meaning people who touch a dog should wash their hands before eating, and restaurant staff should not touch any dogs in the restaurant at all.

Does this mean we should be allowing dogs in all restaurants? Not necessarily. The biggest weakness of even the most logical infection control measures is lack of compliance - people who break the "rules". For example, would people actually minimize contact with the dog and wash their hands? Would food servers really stay away from them? Would all dogs be adequately trained never to bite, scratch, jump up or behave inappropriately in a busy restaurant environment? Furthermore, people with allergies to pets and fear of dogs need to be considered.

In the end, most dogs probably would not cause a problem in most restaurants around most people… but "most" is not "all". Clearly, this is not a straightforward issue, and there are logical arguments on both sides.

Diagnosis of TB in pets is not particularly surprising, since it has been clearly shown by a few other infectious diseases that disease trends in people can sometime be reflected in their pets. It's hard to say if this is an under-recognized problem, an emerging problem or a very rare event that gets a lot of publicity. Really, the only way to tell will be to see what happens over time. Currently, TB is very rare in pets so it is important to keep possible risks and concerns in perspective. There is no reason for pet owners with TB to give up their pets. People with active TB should consider their pets as part of the family, and interact with them as they have been instructed to with people (i.e. if they are supposed to avoid close contact with people they should do the same with their pets).

There is currently no indication that infected pets can transmit TB back to people, and the risks are probably very low. TB is most easily spread through coughing, and pets with TB rarely develop respiratory disease with coughing. That, combined with the rarity of TB in pets, means that the risk of acquiring TB is much, much higher from other people than from pets.  

This is just one more example of the "one medicine" concept, whereby we need to break down the barriers between 'animal diseases' and 'human diseases' (because the bugs are clearly doing so).

• The biggest health risk is actually probably from dog bites. Bites can be avoided through proper handling and training of dogs that are brought to public beaches.
• Many different bacteria (e.g. Salmonella, Campylobacter) can be passed in the stool of even healthy dogs. Some of these can be harmful to people, but only under certain circumstances, such as if they are swallowed or if they contaminate an open wound.
  • Promptly picking up any stool passed by a dog greatly reduces the risk of significant contamination of the sand. Also, sunlight is an excellent “disinfectant” and will help kill any residual bacteria left behind.

• Dogs can also have different kinds of zoonotic parasites in their stool.
  • Some of these parasites (e.g. roundworms, hookworms) are passed in a form that takes days to become infectious to people. So promptly removing dog stool from the beach minimizes the risk of transmission.
  • Other parasites, such as Giardia, are immediately infectious when passed in the stool, but must be swallowed to cause infection. Prompt removal of dog stool, good hand hygiene with soap and water or an alcohol-based hand sanitizer before eating, and avoiding sand contamination of food and drink should largely eliminate this risk as well.

Overall, the risks of having dogs on beaches are very low if people behave responsibly, specifically properly restraining their dogs and promptly picking up stool.

More information about zoonotic diseases associated with contamination of sand and Sandboxes is available on the Worms & Germs Resources page.

Listeriosis is an infection caused by the bacterium, Listeria monocytogenes. It can affect many animal species, but it is rarely identified as a cause of disease in dogs and cats. When signs do occur, fever, diarrhea and vomiting are most commonly reported.  Rare cases of neurological disease in dogs and cats, and one case of suspected miscarriage in a dog due to listeriosis have been reported. Listeria skin infection has also been reported in dogs.

Overall, the risk of listeriosis in pets associated with the tainted meat products is very low. Pets that ate any of the recalled food products do NOT need to be tested or treated if they are not ill. However, should a pet that ate recalled meat become ill, it is important to inform the animal's veterinarian about the potential exposure to Listeria.

Here are some of the key points to remember about EEE:

• Like West Nile, EEE is a seasonal disease.  It is more common in warmer areas, especially some regions of the southeastern US.  It is rare in cooler climates, but occasionally EEE is found in horses in Ontario.
• EEE is usually fatal in horses, and there is no effective treatment.
• EEE can also occur in people, and can be fatal in some cases.
• Infected horses cannot transmit the EEE virus to people, but if a horse gets EEE from the mosquitoes in the area, then people could also potentially be exposed to the virus by mosquitoes.
• A vaccine for EEE is available for horses, but most horses in Ontario are not vaccinated for EEE because it is so rare.  Nonetheless, vaccination can be considered because the disease is so devastating when it occurs.
• As for West Nile virus, avoiding mosquitoes - for both horses and people - is an important preventative measure for EEE.

For more information, see the Worms & Germs Blog post "Eastern Equine Encephalitis – Not Just For Horses", or the CDC's website on arboviral encephalitides.

Toxoplasmosis is caused by the protozoal parasite Toxoplasma gondii.  Infection of a pregnant woman with Toxoplasma can cause birth defects or even miscarriage. But the real risk occurs when a woman who has not been previously exposed to Toxoplasma becomes infected during pregnancy. Pregnant women who were exposed to Toxoplamsa before they became pregnant, and therefore already have antibodies against the parasite, are not at risk.

Cats are the only animal species that can spread Toxoplasma in their stool. Only a very small percentage of cats are shedding Toxoplasma at any one time, but the proportion can be higher among cats that go outside, hunt or are fed raw meat. It takes 24 hours or more for Toxoplasma in cat stool to become infectious - a person cannot be infected with Toxoplasma from fresh stool. This key point can greatly reduce the risk of transmission from a cat, if the cat's litter box is cleaned out on a daily basis.

Any infection that can potentially have devastating effects on a fetus needs to be taken seriously. While it appears to be rare these days, some women are still advised to get rid of their cats if they are pregnant. Pregnant women do not need to give up their cats!  A few basic measures can greatly reduce the risk of transmission of Toxoplasma from cats to pregnant women:

• Pregnant women should not have contact with litter boxes (or any cat feces) if possible - preferably another person should do the litter box cleaning.
  • If a pregnant woman must clean the litter box, it should be done daily so that Toxoplasma does not have enough time to become infectious.
• Litter boxes should be regularly scrubbed and cleaned with scalding water (see the Worms & Germs Resources page for more information on Litter Boxes).
• Keep your cat's fur free of stool contamination.  This is especially  important in longhaired cats that might get stool on the fur around their hind end, or sick/old/obese cats that have difficulty grooming themselves properly.
• Keep your cat indoors. Outdoor cats are more likely to be exposed to Toxoplasma and spread the infection.
• Do not feed your cat raw meat.
• Wash your hands thoroughly after cleaning the litter box, handling raw fruit and vegetables, and working with soil (for example, in the garden).
• Cook all meat completely to recommended temperatures, and practice safe meat handling to prevent spread of contamination from raw meat to kitchen surfaces and other food.

More information about Toxoplasma and zoonotic diesases associated with Cats can be found on the Woms & Germs Resources page.

A blood test can be performed to determine antibody levels (also called a titre) against rabies virus. However, there is not enough information available to determine what antibody titre is high enough to say that an animal does not need to be re-vaccinated. Skipping rabies vaccination based on blood test results is dangerous and not recommended. While rabies is uncommon in most areas, exposure can occur, even in strictly indoor animals (e.g. if a bat gets into the house). Rabies vaccination is a legal requirement in most areas of Ontario. The implications of rabies exposure in an animal that is not "up-to-date" on its vaccines can be severe, including prolonged quarantine or euthanasia. I do not know of any jurisdictions that allow rabies antibody levels to be used in place of vaccination, and animals that are not recently vaccinated are treated as non-vaccinated, regardless of their antibody titre.  The risk to your family or your pet from rabies is greater than the very tiny risk of vaccine-associated sarcoma. If you care about your pet and your family, make sure your pet is properly vaccinated against rabies.

More information about rabies can be found on the Worms & Germs Resources page.