Group A strep and dogs
I was asked this the other day, in regards to a post about pets and recurrent strep infections in people: "You listed a few things to remember and one of them was how the pet might be an "innocent bystander infected by a family member." Is there any indication that a dog might get sick from licking a person infected with Group A Strep?"
Streptococcal infections in dogs are very rare. When they occur, they are typically caused by Streptococcus canis, a Group G strep. Group B strep infections have also been reported. I'm not aware of any reports of Group A (Streptococcus pyogenes) infections in dogs, despite the fact that exposure is probably very common.
Group A strep is a predominantly, if not exclusively, human pathogen. It can be found in healthy individuals (e.g. in the throats of 10-15% of healthy kids) and is the main cause of strep throat. Group A strep also causes invasive infections such as cellulitis, various soft tissue infections, and in rare circumstances, necrotizing fasciitis (flesh-eating disease). Considering how commonly healthy people carry this bacterium and how common strep throat is, you have to assume that dogs are frequently exposed to this bacterium from household contacts.
Licking a healthy human carrier would certainly create an opportunity for a dog to be exposed. Licking wounds of patients with strep infections would probably be worse. Since exposure is probably common and we don't really identify problems in dogs with this bacterium, the risk of infection in dogs is presumably very low. However, basic measures should always be used to reduce the risk of exposure to infectious agents. Even though we don't recognize Group A strep as a problem in dogs, you don't want your dog to be the first case. Dogs shouldn't be allowed to lick infected wounds for both the health of the dog and the person. Strict avoidance of people with strep throat doesn't make sense, but licking should perhaps be avoided since the sick person could also be at higher risk for a secondary infection from the multitude of bacteria present in the dog's mouth.
Bottom line... the risk of Group A strep infection in dogs is minimal, but basic hygiene practices can make the risks even lower.
Rabies death in Indiana
An Indiana woman has died of rabies. Little information is currently available. Reports state that bat rabies was involved but that the source of exposure was not known. Presumably, they have determined that she was infected by the bat rabies variant (strain), but she didn't report being bitten or otherwise exposed to a bat. Bat rabies is a serious concern because it is easy to get bitten by a bat and not know it. Most cases of rabies in Canada and the US are associated with bat exposure. This is a tragic reminder about why we pay a lot of attention to bats and rabies (and why my family received post-exposure treatment after having a bat in the house a few years ago).
More information about rabies can be found on the Worms & Germs Resources page.
No spleen + dog bite = beware
A report from Seattlepi.com is a textbook example of what can happen to certain people after dog bites. Mike Moore tried to break up a fight involving his two dogs and received a minor bite. It barely broke the skin. No big deal, eh? Well, perhaps for most people, but unfortunately not for Mr. Moore.
He cleaned the wound and didn't think much about it. Two days later, he thought he had the flu. The next day, he was worse and went to the hospital. By the time he arrived, "his face and body had a bluish tint" ...never a good sign. When he was being examined, he was asked about the scar on his abdomen and he told the hospital staff it was from his spleen having been removed. They then asked about the bandage on his hand and he mentioned the dog bite. (Insert big ringing bells here!) The article says that the medical staff couldn't pinpoint the problem right away, but hopefully Capnocytophaga was a leading thought. Mr. Moore was critically ill by this point with multiple failing organs. He was admitted to ICU, became septic (overwhelming infection in his bloodstream) and was put on a ventilator. His hand had to be amputated, as did both legs below the knee and three fingers on the remaining hand. But he survived. (Despite the obvious long-term problems, he's very lucky to be alive after such a severe infection).
People that have had their spleens removed or who have non-functional spleens are at much greater risk for various infections, such as Capnocytophaga infections. No one should be allowed to leave a hospital after having their spleen removed without a letter saying, among other things, if you are bitten by a dog, get thee to a physician (pronto)! If you don't have a functioning spleen, make sure you know the risks and how to protect your health.
More information about Capnocytophaga and bites can be found on the Worms & Germs Resources page and in our archives.
Pets and H1N1 revisited
The recent discovery of H1N1 influenza in a pet ferret has led to another round of concern about the potential impact of H1N1 on pets and pets as a source of human infection. Finding H1N1 in a ferret is not particularly surprising, considering ferrets are susceptible to various (including human) influenza viruses. We shouldn't dismiss the potential that certain pets could become infected by this virus or transmit, it but the overall risks are presumed to be very low. There have obviously been many, many cases of H1N1 influenza in pet owners, yet there is just this one report in a pet (although it's certainly possible that other pets have been infected but not diagnosed). Ferrets may be the biggest concern. Pet birds and pot-bellied pigs may also be at higher risk considering this virus can clearly infect pigs and birds. Cats are probably a bigger concern than dogs because of what we know about cats' susceptibility to (and ability to shed) H5N1 (avian) influenza.
The risks are low to pets and pet owners, but there's rarely a no-risk situation with infectious diseases. A few basic measures should be taken to reduce the risks associated with this pandemic virus:
- If you have (or think you may have) influenza, treat you pet like other people in your family. Avoid contact with them, especially their faces, and pay close attention to hygiene (especially handwashing). This should help reduce the risk of exposing your pet to H1N1.
- If you have influenza, or your pet has been exposed to anyone with influenza, and your pet becomes ill (e.g. respiratory disease, fever, lethargy), contact your veterinarian. Avoid close contact with your sick pet (especially the face) and wash your hands after you handle it.
- Relax and enjoy the company of your pet. The risks of influenza are low.
Swine flu has gone to the birds
Just when all those turkeys that managed to survive Thanksgiving weekend thought their troubles were over, there's new issue: H1N1 influenza (formerly known as swine flu) has been found in an Ontario turkey flock. The H1N1 virus was first reported in birds in Chile in late August.
This is not a reason to panic. No one can get the flu from eating a properly-cooked Thanksgiving turkey (nor from any other type of properly-cooked turkey). The producer has voluntarily (and very responsibly) quarantined the affected flock, and no birds or eggs have left the facility. There is no risk to the food chain.
Pigs can be infected by human, pig and bird flu viruses, and multiple infections can result in viruses trading genes and producing new viruses that can infect more species. So it's not too surprising that H1N1can infect people, pigs and now birds as well. This incident serves as an important reminder that we need to remain diligent about infection control and hygiene, even around animals. It's highly unlikely that these turkeys had contact with infected pigs - most likely the virus was spread to this flock by a person. Poultry producers may therefore need to consider getting vaccinated for H1N1 flu not only to protect themselves, but also their flocks, and anyone who may have the flu should definitely stay off these farms. Hopefully the virus does not become established in wild bird populations (like H5N1 has in some areas), as this would make it much harder to control.
Recommendations for avoiding the flu (H1N1 or other) remain the same:
- Wash your hands and/or use alcohol-based hand sanitizer
- Sneeze into your elbow
- Disinfect commonly touched surfaces
- Stay home if you are sick
- Get vaccinated!
Horse Strep in a person via a dog
Streptococcus equi subspecies zooepidemicus (usually just called Strep zooepidemicus) is a common cause of infection in horses. It is an "opportunist" that is often found in healthy horses, but which can cause disease in certain situations. While horses are the natural host of this bacterium, sporadic infections and outbreaks are occasionally reported in dogs at cats, particularly in shelters or other crowded situations. Severe (including fatal) pneumonia can occur, as was reported in a recent outbreak in a humane society in Ottawa. Rarely, S. zooepidemicus can also cause infections in people.
A report in the Journal of Medical Microbiology (Abbott et al) describes a serious S. zooepidemicus infection in a person, that was traced back to a dog. The dog lived on a farm that also had horses. It developed pneumonia and S. zooepidemicus was isolated from its respiratory tract. The dog was treated and recovered. However, the dog owner also became ill with fever, headache, a stiff neck and general malaise. Penicillin was prescribed, but the person's condition did not improve and he/she ended up in the hospital. Streptococcus zooepidemicus was also isolated from this person's nose and throat. When the dog and human strains were compared using molecular tests, they were related. An investigation of the farm was performed, and while all the horses present at the time were negative for S. zooepidemicus, the bacterium was isolated from a healthy dog.
This is a rare situation and one that shouldn't result in too much concern. It does highlight a couple points that are good to remember:
- Getting cultures is very important for obtaining a diagnosis.
- Animal contact and pet health should be considered whenever someone is sick with a potential infectious disease. Physicians need to know whether their patients have contact with animals. They need to be told if a sick animal is present so they can consider whether the pet and human illness might be related. Knowing to what someone may have been exposed might speed up diagnosis and appropriate treatment.
- Rare things are rare, but they happen. We shouldn't focus on rare events but we have to keep our minds open and recognize that strange things happen with infectious diseases.
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.
News flash: You can't sue a dog
A lawsuit against various parties, including a dog, has been tossed out by a Michigan judge. Inez Starks sued the city of Warren, several police officers and Liberty, a police dog, after being bitten during some sort of confrontation in 2007. I don't have any details about the bite, but "unprovoked attack" and "police dog" don't tend to go together. Police dogs can and will bite in certain situations, but these are extremely well-trained and well-handled dogs. Most people that are bitten by a police dog probably have themselves to blame more than anyone else. Inadvertent bites could potentially result from being an innocent party in the middle of a confrontation, I guess, but there is no indication this person was merely an innocent bystander.
Anyway, the suit was tossed out by the judge. As a good example of sanity in the legal system, the judge fined Starks' lawyer for naming the dog in the suit.
Dog bites are a big deal and the cause of many lawsuits. Dog owners need to take their responsibilities seriously to reduce the risk of bites (and consequently being sued). At the same time, people need to take responsibility for themselves to reduce the likelihood of being bitten when confronted by a dog. Usually, that's focused on "be a tree" training in kids, but not upsetting police dogs is probably another good rule of thumb.
Staph pseudintermedius infection in a person
When I talk about methicillin-resistant Staphylococcus pseudintermedius (MRSP), I usually say that the human health risks are low because human infections are very rare. However, rare doesn't mean it can't happen, as demonstrated by a case report entitled "Beware of the Pet Dog: A Case of Staphylococcus intermedius Infection" published in the American Journal of Medical Sciences (Kempker et al 2009).
This paper reports about a post-operative sinus infection in a 28-year-old woman. Cultures were taken and the bacterium was initially misidentified as a coagulase-negative Staphylococcus. It was then misidentified as S. aureus, and finally determined to be S. intermedius. In reality, that's probably another misidentification because the bug almost certainly was truly S. pseudintermedius. (It's become clear over the past couple years that S. intermedius is basically non-existent in dogs and that what has been called S. intermedius in the past is truly S. pseudintermedius).
It's important to remember that human infection with S. pseudintermedius is a rare event. Whenever you see a single case reported, you know it's a pretty uncommon or novel event. Further, this was a post-operative infection, not a spontaneous infection occurring in a low-risk person. At the same time, we need to make sure we don't completely ignore the potential risks. While the risk of transmission of S. pseudintermedius (including MRSP) seems to be very low, we shouldn't ignore it completely. Isolation and other strict measures aren't indicated when dealing with a pet with S. pseudintermedius infection, but general attention to basic hygiene practices and avoiding contact with the infected site is still a good idea.
Internet drug buyers beware
The US Food and Drug Administration (FDA) has warned consumers about buying antiviral flu treatments over the internet. The FDA issued this warning after it tested "Tamiflu" purchased over the internet. Most of the products contained oseltamivir, the active ingredient in the original Tamiflu, but at varying concentrations. Some were pretty obviously a problem, such as one of the orders that arrived in an unmarked envelope with a postmark from India, and consisted of unlabeled, white tablets taped between two pieces of paper. These tablets contained talc and acetaminophen (the active ingredient in Tylenol), but no oseltamivir.
The commissioner of Food and Drugs, Margaret A. Hamburg, M.D, stated in the FDA press release that “Medicines purchased from Web sites operating outside the law put consumers at increased risk due to a higher potential that the products will be counterfeit, impure, contaminated, or have too little or too much of the active ingredient.”
Another issue is that a drug like Tamiflu needs to be given very early in disease to have any effect. If you think you're getting the flu and order Tamiflu over the internet, it's pretty unlikely to have any chance of working by the time it actually arrives (if they send you the appropriate drug in the first place). Then there's the concern that few people actually need to use Tamiflu compared to the number that do, and that viral resistance to Tamiflu may develop with unnecessary use.
Bottom line: if you really need medication, you should get it from a reputable source on the recommendation of a physician. If your pet needs mediciation, you should take the same approach. It's hard to be certain about what you're getting if you order it through the internet, especially from companies that are illegally selling prescription drugs. It might seem cheaper to buy drugs over the internet, but if it's not needed or it's fake, it's going to cost you more in the long run.
Who should pay for Hendra virus research?
A proposed levy on horse owners to fund Hendra virus research has been met with opposition in Queensland. It has been suggested that a $25/horse levy in Queensland would provide needed funding for research into this rare but deadly disease, but this has been opposed by some vets and horse owners. One comment in response to the suggestion of a Hendra virus research levy is that the disease kills humans, so it should be publicly funded. However, Hendra only affects humans who have very close contact with horses, so that's a questionable argument. Also, medical research funding is certainly not overflowing, and the odds of a study such as this getting funded this way may be limited because it is so horse-oriented. I run into the same problem all the time with zoonotic disease research grants. Medical agencies don't want to fund it because it's too animal related, while animal agencies don't want to fund it because it deals more with human health.
Who should fund equine research? Should the government (i.e. all taxpayers) be solely responsible, or should some of the responsibility fall on horse owners, who stand to benefit the most from equine research? This is particularly true for a disease like Hendra that is very rare, currently restricted to one region, and only affects horses and people associated with horses. The rarity of the disease means that industry (e.g. vaccine companies) is probably not eager to fund research (because it would not be profitable). The focal nature of the problem geographically may limit interest from national or international groups. These factors could result in failure to do the necessary research to try to control this deadly disease.
This raises broader questions about funding for equine research. Many people and governments make lots of money from horses, directly or indirectly. You'd like to think that since so much money is made off the backs of horses (both figuratively and in some cases literally), that some of the profits would be put back into helping ensure the health and welfare of these animals. A fraction of a percent of the money generated by horses would be a tremendous asset for equine research, and help make great strides in improving the health and welfare of horses. Unfortunately, such funding is rarely available, and equine researchers are often very limited in terms of the research that can be done with the available dollars. As a researcher, I know the difficulties of finding enough research funding to pay laboratory personnel and grad students, plus perform high quality research. The limited funding that is available is one reason that equine research is now only a fraction of my overall research program. The equine industry as a whole needs to think about its role in research, even if it's from a self-serving standpoint whereby research is funded to help boost performance and profits.
This Worms & Germs blog entry was originally posted on equIDblog on 14-Oct-09.
Rabies and roadkill
Here's a recent question: "Can a rabies virus get into the body if you pick up a dead animal the roadway and have a cut on your hand? I understand the animal has to carry the rabies virus but sometimes we don't know what killed the animal. It may be infected and didn't use due diligence or perhaps it just wasn't fast enough. After reading stories here I'm less likely to remove a dead animal. Sometimes they are so juicy, the fluids are flung about and you may get some on your clothes or skin and not know it. How likely is contracting rabies from fluids in a cut? The reason I ask is when I was younger I picked up a dead squirrel with my bare hands and then noticed I had cuts on my hands. I went to a doctor who looked at me like I was crazy but I had that uneasy feeling because I knew rabies is almost always fatal. Of course, I didn't get it but when I watch other people remove dead animals from roadways I cringe. I can't even think about eating roadkill or skinning it for the fur but that's just me."
Good question. You've covered most of the important aspects of risk, which are pretty minimal:
- Animal has to be infected
- Live rabies virus needs to be present
- Rabies virus needs to get into a person's body (not just on it)
Let's look at these individually.
Animal needs to be infected
- You never know whether this is a concern when you find a dead animal. Once it's dead, you can't tell if it's acting strange. In general, it's safest to assume that all such animals are infectious until proven otherwise.
Live rabies virus needs to be present
- I haven't come across good information about how long rabies virus can survive in a dead body outdoors. It probably varies greatly between different situations, particularly depending on the temperature of the body. For very fresh roadkill, there's certainly a possibility that live virus is still present (if the animal had rabies).
Rabies virus needs to get into a person's body (not just on it)
- Rabies cannot be transmitted through intact skin. Rabies infection is transmitted mainly through bites, cuts and scrapes. Saliva or nervous system (e.g. brain) tissue are infectious. Blood, urine and feces are not.
- If you have contact with a dead animal, avoid any direct contact with your skin, and avoid any activities that could result in splashing of fluids. Transmission of rabies from infected fluids is possible if it comes in contact with broken skin or mucous membranes like the eyes or mouth.
- If intact skin has been contaminated with fluid, wash it thoroughly with soap and water, but don't panic - it's really of minimal concern.
- If your clothes have been contaminated with fluid, take them off right away if possible. If that's not practical (or legal), take them off as soon as you get home. Put them in the laundry immediately and wash your hands.
- If open sores or other broken skin has been contaminated, wash the area thoroughly with copious amounts of soap and water under moderate pressure. Disinfectants can be used to help clean the wound, but there's no consensus about whether that's necessary - these chemicals can be painful to use and hard on tissue, and the flushing action of the water probably does the most to remove the virus from the area. You should go to a physician, who will get in touch with public health personnel to determine if there is any reason for post-exposure treatment. If the animal's body is available to test, that's useful. If the brain has decayed too much to be tested properly, it's questionable whether live rabies virus would still be present even if the animal had rabies. Public health personnel will decide whether they think there is any risk.
Bottom line: the risk of contracting rabies from roadkill is very low. Roadkill contact has never, to my knowledge, been identified as a source of infection. Rabies transmission from dead animals has been documented, however, such as a couple cases of rabies from people preparing dead animals for food.
So, if you see a dead animal by the road, leave it alone. If you are going (for some reason) to touch it, first make sure it's really dead. An injured animal might be much more likely to bite. If it's really dead and you are just trying to move it off the road, use a stick, shovel or something else that doesn't involve you having direct contact with the animal. Other than that, I'm not sure why anyone would want to touch roadkill.
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Image (top) from www.michiganimaging.com
Image (bottom) from http://users.frii.com/donlight/archive/97arc.htm
How do you disinfect a cat?
I was talking with a colleague the other day and somehow norovirus came up. He explained how once, his wife had viral gastroenteritis and ended up vomiting on their cat. Weirdly enough, his wife told my wife the same story (they work together). My wife got a better version of the story which included a nice image of her chasing the cat around the house in her sickened state because the cat was splattering vomit all over the place. (Yuck!)
Anyway, beyond being an entertaining story (as long as it's not you doing the puking and chasing), it raises the question: if you've turned your cat into a biohazardous (and stinky) norovirus vector, what do you do to clean it up?
Dogs and cats cannot become infected with norovirus. However, they could potentially act as a source of infection for people if their coats are contaminated with the pathogen. Usually, I think about this in the context of someone having a little contamination of their hands and subsequently touching a pet (not a vomit-soaked animal, although evidently that can happen too).
So, what should you do? I don't really know. The CDC recommends using bleach or another approved disinfectant on contaminated surfaces, but that's obviously not an option for a cat. Heating contaminated objects to 60C is another recommendation, but again, not for a live animal.
I guess giving the cat a bath would be a good start, and it would presumably greatly reduce the amount of norovirus on the coat. However, if you have viral gastroenteritis already you're probably not in much of a state to do that. Another family member that is not flat-out sick in bed could do the job. However, anyone bathing a heavily contaminated animal should wear a mask and gloves, change their clothes after, clean any surfaced that get contaminated in the process with bleach or another disinfectant, and (of course) wash their hands. Unfortunately, I suspect if you had to bath a cat covered in norovirus that you would probably end up getting infected, either from the cat or the contaminated environment. Leaving the animal covered in vomit is not a good alternative either, since it would continue to contaminate the household as well as look and smell really bad. We don't know how long norovirus can survive on an animal's coat, but it's reasonable to suspect that it could survive a couple of days. Keeping the pet away from uninfected individuals for a week or so wouldn't be a bad idea.
The easiest way to handle this is to avoid vomiting on your pets.
Antibiotics, pets and Clostridium difficile
Clostridium difficile is a high-profile bacterium, being an important cause of illness and death in people. It can also be found in various animal species, including dogs and cats. In a study we published earlier this year (Lefebvre et al, Journal of the American Veterinary Medical Association, 2009), factors associated with acquisition of Clostridium difficile by dogs involved in hospital and non-hospital therapy programs were assessed. Things that were significantly associated with a dog acquiring C. difficile were:
- Contact with human hospitals: Not too surprising since it's clear that hospitals can be highly contaminated with C. difficile and the hands of some patients petting the dogs are probably also contaminated.
- Contact with children: Most parents know that kids are biohazardous (we've getting over a round of illness in our house brought home by the kids - not an unusual event). Whether the increased risk for dogs is because kids have higher rates of C. difficile carriage, or because they have closer contact with dogs (with little hygiene) or some other factor isn't clear.
- Recent use of antibiotics: No surprise here. Antibiotic use is a well-recognized risk factor for C. difficile, since antibiotics can disrupt the normal protective bacterial population of the intestinal tract and allow C. difficile to grow.
- Recent use of antibiotics by a person in the house: I think this is a fascinating result and a great example of the close inter-relatedness of people and pets microbiologically. What presumably happens is that when someone is treated with antibiotics, they are more likely to acquire C. difficile and pass it in their feces. By doing so, there is a greater chance that their dog will be exposed to C. difficile, perhaps from the person's hands or the household environment. (The toilet would be a great source if the dog's a toilet-drinker). The implications of this, for both dogs and people, are unclear. It could be primarily an academic risk (i.e. of little practical significance), or it could be that interspecies transmission of C. difficile plays a role in disease in both species. We simply don't know at this point.
This is also a good example of why educational efforts regarding prudent antibiotic use need to be directed at both animal and human healthcare.
More information about Clostridium difficile can be found on the Worms & Germs Resources page.
Image source: www.sciencedaily.com/releases/2009/05/090507101820.htm
Rabies in vaccinated dogs and cats
A study in the Journal of the American Veterinary Medical Association (Murray et al 2009) investigated the rabies vaccination history of dogs and cats diagnosed with rabies in 21 US states between 1997 and 2001.
- 264 rabid dogs and 840 rabid cats were identified.
- 4.9% of rabid dogs and 2.6% of rabid cats had a history of rabies vaccination.
- Of the 13 dogs that had been vaccinated, only 2 were considered currently vaccinated. Similarly, of the 22 previously vaccinated cats, only 3 were currently vaccinated.
- Texas had the most positive dogs while Pennsylvania had the most positive cats.
This study cannot determine how effective vaccination is. You'd need to know the number of animals that were and were not vaccinated, and then the number that did or didn't get rabies to determine efficacy. The fact that a small number of properly vaccinated animals got rabies shows the vaccine is not 100% protective, which is not surprising.
Vaccination is an important part of rabies prevention, but it's not the only part. Vaccination is a last line of defense - avoiding exposure to rabies is the critical first line. To reduce the risk of rabies exposure, keep your pets under your control at all times. Keep bats out of the house and try to ensure that your house and yard are not welcoming to wild animals. Don't let your pets have contact with wildlife and pay close attention when strangely-acting wildlife are around. Active measures to reduce wildlife rabies such as rabies baiting are also important.
Don't assume because your pet is vaccinated that you don't have to worry about trying to reduce the risk of exposure to rabies.
Don't assume that an animal with neurological disease doesn't have rabies just because it's been vaccinated.
Herd immunity is not just for cows
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Herd immunity is an important infectious disease concept. Basically, it involves trying to ensure that a high enough percentage of a population is resistant to an infectious disease so that the disease cannot be spread easily through the group. Ensuring that a large percentage of the population is vaccinated helps protect individuals that cannot be vaccinated (because of allergy, disease or other reasons) or that did not properly respond to vaccination (not all vaccines protect all vaccinated individuals).
"Herd immunity" usually refers to this concept when applied to herds of animals, but the "herd" can be a small local population, a regional population, or broader, and it can be people or animals. For some human infectious diseases, it's been shown that vaccination of 75-95% of the population is required to prevent outbreaks. If vaccination rates start to slip, the chance of an outbreak increases. This is best seen in some areas where vaccination rates decline in certain groups of kids because parents are reluctant to have their children vaccinated (for one reason or another), and subsequently outbreaks of disease start occurring (or increasing).
Vaccination is an important (but not the only!) infection control tool. For diseases that are transmissible between dogs (or cats, people, or whatever other "herd" is being considered), vaccination of a single animal helps protect that individual from disease, and also helps protect the rest of the population.
During a public health infectious disease course that I teach, a student showed us a link to this interesting and amusing demonstration of herd immunity from the UK. Make sure you have your sound turned on. It's an entertaining description of the concept of herd immunity.
Pet bear kills woman
In yet another tragic example of why large wild species should not be kept as pets, a 37-year-old Pennsylvania woman was killed by her pet black bear. She entered the 350 pound bear's cage, a 15 by 15 foot steel and concrete enclosure (hardly a good environment for a bear) and was mauled. A neighbour then shot and killed the bear. A Bengal tiger and African lion were also present on the property. No indication was given about what might have triggered the attack.
Large carnivorous mammals don't make good pets. It's also questionable whether people can adequately and humanely care for such animals. I have a hard time believing the bear had a good quality of life living in a small steel and concrete pen. The picture above is not from this case but from another bear enclosure elsewhere in Pennsylvania (see link here).
Every year, there are reports of these types of "pets" severely injuring or killing their owners, yet there is little effort in many regions to control the ownership of these animals. Local officials knew about these animals and the woman had permits for them. Why (and how) someone could actually get a permit to keep these species is beyond me.
Pets are great, but pet ownership has to be logical and safe, and there have to be benefits for both the human and animal. Keeping dangerous animals locked up for curiosity's sake is no longer (or at least should no longer be) socially acceptable. These animals should be in the wild or in a properly managed zoo or wildlife rehabilitation sanctuary.
So you've been bitten by a dog....
Recently, a relative was bitten by a dog, and the incident emphasized that you need to take such things seriously and pay attention to making sure things get taken care of properly.
So what should you do if you've been bitten?
1) Identify the dog.
- You need to know who the dog is, and who owns it. If you can't identify the dog, you have to assume it's rabid (even though it's extremely unlikely) and get treated with a series of vaccinations.
2) Get medical care as needed.
- Bites can be associated with significant trauma and risk of infection. Getting to a doctor is particularly important if the bite is severe, occurs at a high risk body site (e.g. over the hands, joints, tendons and nerves, groin, prosthetic devices) or if you are at higher risk of infection (e.g. immunocompromised, don't have a functional spleen, very young or very old, pregnant). If in doubt, go to a doctor to be on the safe side.
Once you've done this, it's important to make sure that the offending dog actually doesn't have rabies. If you go to a doctor, they will (in most regions) report the bite directly to public health. Public health inspectors will investigate the rabies vaccination status of the animal and ensure that it is quarantined for 10 days. If the dog has rabies and is infectious, it will develop signs of infection within this 10 day period. If the dog is healthy after 10 days, it did not have rabies at the time of the bite.
Seems pretty simple, eh?
Unfortunately, there are a few places where this process can break down.
Reporting: All bites need to be reported. Bites that do not result in people going to the hospital may be missed. You don't need a serious bite to contract rabies (or another serious infection).
Public health follow-up: This is hopefully not an issue, but you should make sure that public health has investigated, and done so promptly. Don't be afraid to call to find out the status of the investigation, and make sure information has flowed quickly from the physician to a public health inspector. Hopefully they'll be in touch with you, but don't be afraid to initiate contact. The main issue with follow-up relates to the next point:
Prompt euthanasia of the dog: Sometimes, people will decide to euthanize a dog after a bite, because it's done it before, because they consider any bite unacceptable, and/or they fear for family members or legal liability. Dogs (or cats) that have bitten someone must not be euthanized before the 10 day quarantine period is over. If the dog is euthanized and the body is not available for testing, you have to consider the dog rabid and undergo post-exposure treatment. Veterinarians are required to ask whether a dog has bitten someone in the preceding 10 days prior to performing euthanasia, but it's possible that this could be missed, or people may not tell the truth because they want to have the dog put down ASAP. This is why public health inspectors need to investigate promptly - to provide another level of assurance that the animal is not euthanized inappropriately. You should follow up with public health to make sure things are underway and the dog is quarantined.
Rabies associated with dog bites is extremely rare in Canada (and many other countries) but still kills tens of thousands of people every year, mainly in Asia and the Middle East. Considering it's almost invariably fatal and pretty much 100% preventable, you need to pay attention to the risks, no matter how small.
Giardia in dog parks
There is a recent paper in Preventive Veterinary Medicine about a study of Giardia in canine stool samples collected from urban green areas around Pisa, Italy (Papini et al). The authors went to parks and similar areas and collected stool samples off the ground. They then tested the samples for the presence of Giardia and (very importantly) tested the Giardia to determine whether they were types that typically only infect dogs or whether they were types also found in people.
They found that 31% of stool samples contained Giardia. That's higher than in some recent North American reports. The number of Giardia cysts ranged from 2 to 1428 per gram of feces. Less than 1% of the Giardia were types that are of concern for transmission to people. Therefore, they concluded that parks pose a risk to dogs, since there is a good likelihood that dogs could be exposed to Giardia. However, the risk to people from Giardia found in these parks is minimal given the types that were found.
The risks to dogs and people can be decreased by the simple act of picking up poop.
More information about Giardia can be found on the Worms & Germs Resources page, and in our archives.
"Family protection" screening of healthy pets
As public awareness of zoonotic diseases increases, some new marketing opportunities are created. One is offering screening of pets for "protection" of the family. One company, Healthgene, offers a Family Protection Program that involves screening pets for selected zoonotic pathogens. Unfortunately, it involves the use of non-validated PCR tests for pathogens for which screening of healthy animals is not considered useful. They make various unsupported, illogical and sometimes downright incorrect statements such as "If, by chance, any positive results should occur, not only should the animal be treated immediately, but the client and anyone having contact with the animal should also notify their family physician." Despite the fact that the tests themselves are of questionable quality and the results are essentially useless, I'm sure they are developing a market.
Also, it's pretty concerning that this company misspells the names of various microoganisms for which they test on their website - they even misspell "protection" in one of their Family Protection Plan info sheets! Inability to spell isn't necessarily linked to inability to test properly, but it shows a lack of care and attention to detail that raises further red flags in my mind.
Zoonotic diseases ARE a concern. We need to pay attention to them and try to reduce the risks of transmission to people. Screening healthy animals is almost never a component of this. Save your money when it comes to "routine" screening of healthy animals - talking to your vet about potential problems and washing your hands are much better ways to reduce the risk of infection.
