Rare rabbit infection in Manitoba
Rabbit hemorrhagic disease (RHD), a rare and reportable disease, has been identified in a pet rabbit from Winnipeg, Manitoba. The affected adult male rabbit was taken to a veterinary clinic in March after being lethargic for a short period of time. It was diagnosed with liver failure and subsequently died. The rabbit's body was forwarded to the Manitoba Ministry of Agriculture, Food and Rural Initiatives animal health laboratory. Various tests were performed and rabbit hemorrhagic disease was identified.
Rabbit hemorrhagic disease is a viral disease caused by a calicivirus. It is a serious infection that has high death rates and spreads very rapidly between rabbits through direct contact and through contaminated items such as cages and bedding. It does not affect people. Caliciviruses are non-enveloped viruses - viruses of this kind are very hardy, and can survive in the environment for long periods of time. RHD is reportable in Canada, and has not, to my knowledge, been identified in the country before. It's endemic in wild rabbits in many countries, and is thought to have made its way to North America in 1988 in a shipment of frozen rabbits from China to a supermarket in Mexico City. It's been found in the US in sporadic outbreaks since 2000.
Finding RHD in a Canadian rabbit perhaps isn't too surprising, since it's been identified in the US periodically over the past decade. However, this is a strange situation. The affected Manitoba rabbit lived in an apartment with two other pet rabbits, and did not have any outdoor access or contact with any other rabbits (or any other wildlife). These other two rabbits were fine. They were quarantined initially but have since been released from quarantine since they stayed healthy and tests for the virus were negative.
So, where did the virus come from? That's a baffling question, because this virus is a rare and exotic disease that is not known to be elsewhere in Canada. It would have been a lot less surprising if this was in a rabbit with outdoor access or that had had contact with other rabbits (outside of a confined household group). No source has been reported, but I assume authorities have looked at aspects like the owner's contact with rabbits or wildlife, the owner's contact with areas where wild rabbits might live, when the other rabbits were obtained and from where, and whether the owner has brought rabbit meat into the house. Although mice and similar rodents aren't known to be susceptible to the virus, checking for a rodent infestation in the house would be another consideration at in a strange situation like this.
Why were the other rabbits unaffected? That's surprising as well, considering how easily the virus is normally transmitted.
Another thing this story highlights is the usefulness of diagnostic testing. I'm impressed that the owners and veterinarian submitted the rabbit's body for testing. Too often, an animal that dies of a strange disease is just buried or cremated. That's understandable from an emotional aspect, but often it occurs because testing is not even discussed after an animal has died, or because people don't think about why it might be useful. Cost is an issue, as testing is not typically subsidized for non-food-animals (in this case, even though it was a pet, I presume the rabbit was treated as a food animal, with a lot of testing done for free). While testing won't help the dead animal, it can provide useful information at times, beyond finding a rare foreign disease. It's not uncommon for me to get a call from someone saying "my dog recently died of some strange disease, is it safe for me to get a new puppy or do I have to do something first?" or less commonly "I'm sick and the doctors haven't figured it out. My dog died last month of something strange, do you think they could be linked?' With only a vague clinical description, there's often not much I can say.
Rare diseases are just that - rare. The odds of encountering one are quite low, but they do happen. Arriving at a diagnosis can help identify risks to other pets and people, and it is often money and time well spent.
Dumb Easter decisions
Easter is one of those holidays when there are concerns about dumb pet purchases. Spur-of-the-moment purchases of inappropriate pets can lead to animal suffering and death, and risk of human infection. Easter's problems: baby chicks and rabbits.
Rabbits can make great pets. They're a long-term commitment, but they’re relatively low maintenance, a lot is known about how to raise them and they are generally low risk for transmission of infections to people. Chicks are a different story. Chicks are notorious Salmonella vectors and have been linked to numerous outbreaks. They are easily injured and often improperly raised. They also grow up (well, some of them do, at least) to be full sized poultry, something that most people don't really want.
A story from Vidalia, Georgia highlights some of the issues with Easter pets. In it, Tracy Gunn describes his need to buy a chick for his daughter - and not just any old chick, but a dyed chick, something that’s illegal in 36 US states, but not Georgia. Gunn states "I don't know what she's going to do with it." Sounds like a recipe for a few minutes of novelty, followed by a relatively short life for the chick. At least his daughter’s 17, and not in the high risk group for salmonellosis.
Alongside the cage full of multicoloured chicks was a collection of rabbits.
“The bunnies sell real good for Easter. We've been selling a lot of them about the last month. Can't keep enough of them.” said a store employee.
He followed that up with “They buy (rabbits) for their kids for Easter, then they take Easter pictures and stuff like that with them, I'm not sure about what happens to them afterward.”
That’s the problem. Kids get a few minutes of novelty enjoyment, but then a lot of those animals end up dead, released into the wild (not a good thing) or dropped off at an animal shelter, because people don't think about the "afterward" part before they buy.
Pet purchases need to be made with thought and foresight:
- Do I really want this pet?
- Am I committed to taking care of it for its entire life?
- Can I take care of it properly with my current living situation?
- Can I afford to take care of it properly?
- How do I take care of it?
- Are there any disease risks that I need to be concerned about?
- Are there any people in the household who are at high risk for disease caused by this type of animal?
If you can't answer these questions, don't buy or adopt an animal - of any kind.
Tularemia alert in Texas
When it comes to handling microorganisms, there are 4 biosafety levels.
- Biosafety level 1 (BSL-1) organisms are harmless.
- BSL-2 organisms include most of the commonly encountered bugs, including things like E. coli, Salmonella and Staphylococcus aureus. They can cause serious disease but infections are often treatable and they can be handled safely with standard lab protocols.
- BSL-3 organisms are a relatively small group of bad guys that require more extensive facilities and protocols to handle them. These include Coxiella burnetii (the cause of Q-fever) and Francisella tularensis, the cause of tularemia.
- BSL-4 organisms are the really bad guys that require high level containment like you see in the movies. There are a limited number of BSL-4 facilities in the world and they deal with bugs like Ebola virus.
One of the BSL-3 pathogens I mentioned was a bug called Francisella tularensis, the bacterium that causes tularemia, which is also listed as a potential bioterrorism agent. Tularemia is a very nasty disease. It's uncommon but human infections occur sporadically in many regions, typically associated with wildlife exposure. It's often associated with contact with rabbits, but the bacterium can be found in a wide range of animals (including insects) and in the environment.
Recently, people in Bell and Coryell counties in Texas (between Dallas and San Antonio) were warned about the potential for tularemia exposure from wild hogs, since 15-50% of tested feral hogs in those areas had evidence of current of past infection. While evidence of past infection (the presence of antibodies against the bacterium in their blood) does not mean that they are actively infectious, it indicates that the bacterium is circulating in the area and that hogs are being exposed. If a hog was actively infected, it could be a source of human infection if there was direct contact (i.e. hunting and butchering).
Because of the potential risk of exposure, the following recommendations have been made:
- Always wear rubber gloves and eye protection when dressing (i.e. skinning & gutting) wild game.
- Ensure that game meats are handled carefully and thoroughly cooked.
- Use insect repellent to keep ticks, biting flies and other insects at bay.
- Look for rabbit nests in tall grasses before mowing. (As unusual as it sounds, running over rabbits with a lawnmower has been associated with development of tularemia).
The risk of tularemia is pretty low, but it's a very serious disease and you don't want it. Using these basic precautions should help reduce the risk.
E. cuniculi from rabbit to dog?
How likely is E. cuniculi to be trasmitted from an infected rabbit to a dog? My sister has a positive rabbit and my dog was just diagnosed with kidney insufficiency. Now that the dog's kidneys are compromised, should we be concerned?
Encephalitozoon cuniculi is a strange little organism that is now classified as a fungus, but is also similar to some types of protozoal parasites. It is an important (and often overlooked but potentially treatable) cause of neurological disease in rabbits. It is quite common in healthy pet rabbits, and infected rabbits shed the organism mainly in urine.
Less is known about E. cuniculi in dogs. Neurological disease, stunted growth and renal failure are the most common problems that develop. Disease usually occurs in young dogs (less than 1 year of age, with most cases in dogs a couple of months old or younger). Some studies have reported antibodies against the organism in a large percentage of healthy dogs, indicating that they've been exposed at some point, but most studies have found antibodies in few or no dogs.
The risk of transmission from rabbits to dogs is not known. There are a few different types of E. cuniculi, including one type (type I) that is called the "rabbit strain" and another (type III) that is called the "dog strain." The ability of the rabbit strain to infect dogs, particularly dogs with normal immune function, is unclear. Considering the low incidence of infection in dogs (especially older dogs), the different types of E. cuniculi that predominate in dogs and rabbits, and the commonness of kidney disease in dogs, I doubt there's a link between the rabbit's infection and the dog's kidney disease in this case.
Eliminating E. cuniculi in the household
A recent question:
"I have two rabbits who just tested positive for E. cuniiculi... Can you please tell me how to disinfect my floors and kill the parasites? I don't think bleach is doing it."
Encephalitozoon cuniculi is a strange little bug. It a member of a unique group of organisms called microsporidia. Originally thought to be parasites like Giardia, they are now classified as a type of fungus. Regardless, E. cuniculi is common in the pet rabbit population, causing neurological disease in some rabbits but living in many others without any signs of illness.
Infected rabbits shed E. cuniculi spores in urine, feces and respiratory secretions. Other individuals are infected by ingesting (and possibly inhaling) these spores. Infected rabbits start to shed spores in urine a month or two after infection, and can continue to shed low levels of spores intermittently. This, along with close housing of pet rabbits and movement of rabbits between breeders, stores and owners, explains why, in some studies, up to 75% of tested rabbits have evidence of current or prior infection.
Disinfecting household environments can be tough because of the surfaces that are involved. Encephalitozoon cuniculi is quite hardy and can live in the environment for prolonged periods of time. It is susceptible to a several types of disinfectant, including bleach, 70% alcohol and 1% hydrogen peroxide. In general, bleach is highly effective and is probably the standard for disinfection of surfaces that can tolerate it. Obviously, bleach isn't a good option for many surfaces like carpets. Steam cleaning might help, as much for the thorough cleaning component as for the steam.
One thing to consider is whether aggressive household disinfection is really required. While humans can be infected, infections are uncommon and predominantly occur in people with compromised immune systems, especially those with HIV/AIDS. If there are no high-risk people in the household, I don't think I'd be too aggressive with disinfection. Good hygiene practices involving handling of the rabbits and their cage are probably much, much more important, and its better to focus efforts there. Household disinfection for protection of the rabbits is probably not too useful at this point. I would suspect that all rabbits in the household have already been exposed, and since infected rabbits can continue to shed intermittently, rabbits are a much greater source of infection than the household environment.
More information about E. cuniculi can be found in our archives.
Transmission of herpesvirus from a person to a rabbit
A paper in the July 1 edition of the Journal of the American Veterinary Medical Association (Muller et al) describes a case of encephalitis (brain inflammation) in a rabbit caused by human herpesvirus type 1. The owner had a severe herpes infection with genital and oral lesions five days before the rabbit got sick, and reported "intensive" nose-to-nose and mouth-to-nose contact with the rabbit. The rabbit started off with a decreased appetite and excessive tear production (epiphora) in one eye. Then other signs of eye and neurological disease developed. Despite aggressive treatment, the rabbit deteriorated and was euthanized after a week of hospitalization. Subsequent testing identified human herpesvirus type 1 in the rabbit's brain.
Human herpesvirus type 1, also called herpes simplex viruses type 1 (HSV-1), is a common sexually transmitted disease (STD) in people. It can cause oral, genital and ocular (eye) lesions. Humans are the primary host of this virus, but it has been found in species such as rabbits, rats, mice and chinchillas. In rabbits, it usually causes encephalitis, and is almost always fatal for these animals.
This case shows how viruses typically associated with one species can sometimes affect others. While we usually focus on microorganisms moving from animals to humans, they can also move in the opposite direction, as was presumably the case here. Close face-to-face contact with the infected owner was probably the source of the virus. This is an example of an uncommon event, but one that should not be ignored.
If you have an active herpesvirus infection:
- Limit close contact with rabbits (and, to be on the safe side, probably restrict contact with other pets as well). In particular, avoid contact with the mouth, nose or eyes.
- Wash your hands or use an alcohol hand sanitizer regularly, particularly after using the washroom or having any contact with infected sites/sores.
- Make sure herpesvirus infection is considered if your rabbit develops eye or neurological disease.
The risk of rabbits transmitting human herpesvirus is completely unclear. Common sense dictates that anyone hanlding a potentially infected rabbit should restrict contact with the eyes/mouth/nose, wear gloves, wash hands after contact (even if gloves were worn) and avoid contamination of clothing.
Plague in a rabbit: New Mexico
Plague has been diagnosed in a dead rabbit found on a private residence in New Mexico. Plague, also known as the black death, is a highly fatal disease of humans and many animals caused by the bacterium Yersina pestis. While often considered a disease of mainly historical interest - having killed a large percentage of people on the planet during a few pandemics over the centuries - plague is actually still alive and well in some regions. In North America, most cases occur in New Mexico, Arizona, Colorado and California.
Yersinia pestis primarily lives in wild rodents and is transmitted by fleas. Many different animal species, including cats, dogs, rabbits and people, can be infected if bitten by a flea from an infected rodent (hence the historical association of the disease with rats). Predatory species (like dogs and cats) can also become infected by eating infected animals. Dogs are relatively resistant to plague and usually only develop mild disease, while cats and rabbits are as susceptible as people, and can develop bubonic, septicemic or pneumonic plague. Transmission of plague from pets to people can occur, and most often involves cats. People can become infected by close contact with sick pets, or being bitten by a flea from such a pet.
Preventing plague in animals involves flea control and reducing exposure to infected wildlife. In areas where plague is active, all pets should be on a flea control program. Cats should be kept indoors to reduce the risk of exposure (e.g. keeps them from hunting infected rodents). Dogs and cats should not be allowed to have contact with dead animals of any kind. Measures to reduce rodent infestations in and around the house are also important.
More information on plague is available in the Worms & Germs archives.
Ban the Easter bunny?
As Easter approaches, so do the annual commentaries about concerns with people buying "Easter bunnies" (the real variety, not the chocolate version) without knowing what they are getting into. It's a big problem because a lot of spontaneous Easter bunny purchases end up abandoned at humane societies (or worse) after a few months.
In general, rabbits can be great pets. However, they have special management needs, and they can live for a relatively long time (years), so people need to think about whether a rabbit is the right pet for them, and whether they can (or will) look after it properly for the duration of its life.
Rabbits are pretty low risk in terms of zoonotic disease transmission. There are a few concerns but these are typically quite manageable with pretty basic hygiene measures. Knowing how to properly handle a rabbit is very important to prevent scratches (and bites) to the handler, and potentially serious injuries to the rabbit. For more information and a video about safe rabbit handling, see the previous Worms & Germs post entitled "Safe Rabbit Handling - For You And Your Rabbit".
Easter may be as good a time as any to get a rabbit - if it's not a spontaneous decision and you've really put some serious thought into it. Part of that process needs to include finding out about ways to reduce the risk of illness and injury associated with rabbits. This type of information can be found in the rabbit information sheets on the Worms & Germs Resources page.
Cheyletiella - The walking dandruff
Cheyletiella is a genus of mites that commonly affect dogs (C. yasguri), cats (C. blakei), rabbits (C. parasitovorax), and occasionally people. Unlike Sarcoptes species (the mites that cause sarcoptic mange), these mites live on the surface of the skin and do not burrow into deeper layers. They feed on dead skin cells and occasionally tissue fluid. Infestation with these mites can be very itchy, but not always. Cats in particular can carry the mites without any visible abnormalities of their skin or fur. Typically, however, the affected animal's fur becomes crusty, scaly and inflamed, and sometimes patches of fur may be lost. The mites are usually a little less than a half-millimetre long (so they are visible to the naked eye if you look closely) and grayish-white. They tend to be quite active and crawl around (but they don't jump like fleas), which gives them the appearance of walking dandruff. Diagnosis is easy if the mites are seen strolling around on a table or blanket, otherwise they may be found on a "scotch tape test" or superficial skin scraping.
People can be affected too if they have close contact with a pet carrying Cheyletiella. Lesions, which usually take the form of single or grouped small red bumps on the skin, typically appear on the arms, trunk or thighs, and sometimes can be extremely itchy! It is rare to see the mites themselves on a person - usually they're found on the pet. The good news is these mites can't actually complete their life cycle or survive for long on people, and in the environment even the hardiest forms of the parasite (usually the eggs and adult females) die within about ten days. So once the source of the mites is eliminated (by treating the pet with an appropriate anti-parasitic drug which your vet can prescribe), the signs in any affected people will resolve on their own without specific treatment (but you might want something for the itch!).
Photo: Light micrograph of C. yasguri from a dog (credit: Dr. M. Dryden, College of Veterinary Medicine, Kansas State University)
Neurological bunnies: Encephalitozoon cuniculi
Encephalitozoon spp. are single-celled microsporidian parasites that can cause infection in the intestinal tract of animals and people, and sometimes infection in other parts of the body (systemic infection). Cases of infection with these parasites (encephalitozoonosis) have been reported in countries all over the world. The species E. bieneusi and E. intestinalis are the most common. A much less common species, E. cuniculi, is thought to be one of the most virulent microsporidia that infects humans (i.e. it causes the most severe infections). Encephalitozoonosis is rare in healthy people, but it is a common complication in patients with weakened immune systems. Encephalitozoon cuniculi can also be found in many animal species, particularly in rabbits. Most infections in rabbits do not cause illness (i.e. subclinical infections), but when disease occurs it typically causes neurological signs. In these cases the parasite tends to attack the brain and kidneys. The primary means of transmission between rabbits is E. cuniculi spores shed in the urine. Organ damage in the few human cases that have been reported have also been primarily in the brain and kidneys.
Direct transmission of this parasite from rabbits to humans has not been reported, but because there is also no evidence that it can't be transmitted from rabbits, the disease is so severe when it does occur, and the parasite is so common in rabbits, it is still prudent to take a few simple precautions. This includes washing your hands after handling rabbits, and keeping rabbits away from food preparation areas and food meant for human consumption. Anyone with a weakened immune system should be particularly careful, and ideally should have someone else clean out their rabbit's enclosure on a regular basis.
In general, the risk of illness in a rabbit and zoonotic transmission can be reduced by proper handling, good management, personal hygiene and routine healthcare. A rabbit that is not stressed and is well cared for is less likely to be susceptible to infection, and therefore less likely to transmit infection to a person. More information about rabbits is available on the Worms & Germs Resources page.
Safe rabbit handling - for you and your rabbit!
Knowing how to properly handle a rabbit is very important for rabbit owners. If done incorrectly, the handler, the rabbit, or both could be injured. A rabbit's powerful hind legs and flighty nature (being a prey species) are a dangerous combination. Even though rabbits may not do so intentionally, the nails on their hind feet can inflict serious scratches (rivaling those of any cat or dog) if they are trying to get away. Rabbits can break their backs simply by struggling against improper restraint because of the amount of force they can generate with their hind legs.
Knowing the basics about how to handle rabbits safely and correctly can greatly reduce risks to both the handler and the animal. Click on the image below to see a video by Dr. Erin Harrison of the Ontario Veterinary College Avian & Exotics Service about some tips on approaching and handling rabbits safely.
Tularemia Trouble
A case of pneumonic tularemia was recently reported in New York City.
Tularemia is a disease caused by the bacterium Francisella tularensis. It causes different signs of illness depending on how the bacteria enter the body. If the bacteria are inhaled, it tends to cause pneumonia (pneumonic tularemia). If the bacteria get in through a break in the skin, infection may cause the local lymph nodes (glands) to become very swollen, and in some cases the skin itself may become infected resulting in the formation of large sores (ulcers). Infection can also cause sores in the mouth and diarrhea. The earliest, most common signs are things like fever, headache, chills, sore muscles, and sore throat which often come on very abruptly. The infection can be treated with antibiotics, but it is important to see a doctor and start treatment as soon as possible.
Tularemia is also sometimes called "rabbit fever," because the bacteria are often carried by animals such as rabbits and hares. Rodents (including beavers, rats, mice, squirrels etc.) can also carry F. tularensis, and occasionally so can cats and dogs. Some biting insects like deerflies and certain species of ticks can carry the bacteria and transmit it when they bite. Francisella tularensis can also survive in water and soil for a long time. People can become infected by being bitten by an infected insect, handling an infected animal (dead or alive), or coming into contact with feces from an infected animal. Occasionally a person may inhale the bacteria if it is in the air, as may happen with disturbed, dusty, contaminated soil.
More information on tularemia can be found on the CDC's tularemia website.
Things you can do to avoid tularemia:
Avoid touching or handling wildlife (dead or alive), especially rabbits and rodents.
Don't let your pet touch or eat dead animals.
Always wash your hands if you have been working outside in the dirt/soil.
Wear insect repellent containing DEET (visit the Health Canada website for more safety tips)
Make sure you only wash food with and drink water that has been properly treated.
One of the reasons tularemia is such a big deal is it is very infectious - as few a ten bacteria can be enough to make even a healthy person sick! But it is still quite uncommon in North America - about 100-200 cases are reported in people in the USA every year. Between 2002-2004 there were 34 cases reported in Canada, most of which occurred in Quebec and in adults. However, infection can be fatal in a very small number of cases, especially if proper treatment is not given as soon as possible.
Information Sheets for Pet Owners
INFORMATION SHEETS specifically for KIDS, for VETERINARIANS, for PHYSICIANS and for PUBLIC HEALTH PERSONNEL are also available on the Worms & Germs RESOURCES page!
Click on the highlighted topics below for information sheets. Topics that are not highlighted are in development and coming soon. Sheets for other animal species and diseases are also under development and will be added when they are available.
| Animals | Diseases | Other |
| Dogs | Rabies | Litter Boxes |
| Cats | Giardia | Sandboxes |
| Turtles | Toxoplasma | Cat Bites |
| Hamsters | Leptospira | Raw Meat |
| Rabbits | Clostridium difficile | Petting Zoos |
| Pet Birds | Cryptosporidium | Needlestick Injuries |
| Reptiles | MRSA | |
| MRSP | ||
| Salmonella | ||
| Ringworm | ||
| Campylobacter | ||
| Bartonella henselae | ||
Please Remember:
- Your veterinarian and physician are your ultimate resource for information about the health of your pets or your family.
- Information provided here is accurate to the best of our knowledge, but infectious diseases can be unpredictable and these sheets are for general information purposes only.
- There can be great variation in disease risks in different geographic areas. The information provided was developed for Ontario, Canada, but most of the information is relevant for other regions as well.
