Search leptospirosis

Earlier this year, a troop of Boy Scouts in the US beat off a rabid beaver that was attacking their leader (I wonder if there’s a badge for that). Boy Scouts and infectious diseases are in the news again, but not with as happy a story.

In the recent incident reported on ProMED, ten Boy Scouts that attended a camp on the banks of the Semois River in Belgium developed leptospirosis – a potentially severe bacterial infection caused by Leptospira bacteria. The bacteria are shed in the urine of a variety of animal species, and people can become infected through contact with contaminated water or animals. The boys reported having played with a rat, which was likely actually a muskrat, based on the description of its size.

Three of the boys were hospitalized.  Hopefully all are on the way to recovering.

This is yet another reminder that wildlife should be left alone. It’s possible the boys were infected from the environment, but handling a muskrat (which was presumably sick if they were able to get that close to it) certainly increases the risk of exposure to a variety of infectious diseases.

Image of a North American muskrat (photo credit: Linda Tanner)(click image for source)

Veterinarians at Michigan State University’s College of Veterinary Medicine are warning of an upswing in leptospirosis in dogs in the Detroit area. More than 20 cases of leptospirosis have been reported in dogs in the Detroit area, and it’s likely that many more unreported cases have occurred. Leptospirosis, a bacterial infection, can cause very serious disease, including potentially fatal renal failure. It can be vague and hard to diagnosis if people aren’t thinking about the disease. The most commonly identified problem is kidney disease, and early diagnosis and treatment is critical for successful treatment.

The Leptospira bacterium can survive well in the environment, particularly in moist conditions, and dogs are often exposed through wet environmental areas that have been contaminated with leptospires from the urine of infected wildlife. The strain that has predominated in the latest Michigan cases is Leptospira Icterohemorrhagiae, a type most often associated with rats.

Prevention of leptospirosis involves avoiding exposure to the bacterium as much as possible (largely through avoiding contact with wet areas where lepto cases have been identified) and vaccination. Vaccines are available for dogs and they can reduce the incidence and severity of disease caused by four different lepto types, including Icterohemorrhagiae.  Vaccination should be considered in dogs in regions where lepto cases are identified and in dogs at increased risk of exposure based on lifestyle and travel.

(click image for source)

The USDA’s Animal and Plant Health Inspection Service (APHIS) has announced proposed changes to dog importation rules. The changes would tighten rules for dogs being brought into the country for resale, research or veterinary treatment. The reason for the sudden changes isn’t clear, but it may be the result of a couple of high-profile importations of rabid dogs. Regardless, it makes sense to pay more attention to companion animal importations, as long as the requirements are practical. The practicality aspect is of particular concern for the large number of people that travel between Canada and the US with their dogs, which is pretty low-risk from an infectious disease standpoint. Balancing policies that help prevent introduction of serious diseases with rules that don’t unnecessarily complicate the frequent cross-border movement of people and their pets can be tough. This proposal doesn’t cover pet dogs, which is both good and bad.

With the proposed changes, dogs imported for resale, research or veterinary treatment must have:

  • an original health certificate
  • a valid rabies vaccination certificate
  • have an APHIS-issued import permit

The health certificate must clearly describe the dog and certify that:

  • it’s at least six months of age
  • it was vaccinated no more than 12 months prior to the date of importation against distemper, hepatitis, leptospirosis, parvovirus and parainfluenza virus
  • it’s in good health and "free of any infectious disease or physical abnormality that would endanger the dog or other animals or endanger public health, including parasitic infection, emaciation, lesions of the skin, nervous system disturbances, jaundice or diarrhea."

That’s pretty standard, however the last statement can sometimes cause issues. Here, the language is better than in some other protocols because it says "disease," not "infection." It may seem like a minor point, but to me it means a lot. If someone asks me to certify that my dog does not have an infectious disease, I can do that. She doesn’t have any clinical evidence of an infection. If someone asks me to declare that she’s free of infection, it gets trickier, because infection could be interpreted as disease, but it could also be interpreted as simply carrying an infectious agent. Every dog is carrying multiple microorganisms that could "endanger the dog or other animals or endanger public health" but the risk is rather low from clinically healthy dogs. No veterinarian can ever certify that a dog is not carrying any microorganism that could cause disease.

The restriction of importation for veterinary treatment is a bit of a concern, because in some areas the closest veterinary clinics or referral centres are across the border (one way or the other). It’s a difficult issue, because dogs being taken to a veterinarian may be sick, and a veterinarian can’t certify that such an animal is free of disease. The report states that "limited exceptions" will be made for the health certificate and rabies vaccination certificate for dogs imported for veterinary care. What "limited exceptions" means and how quickly an exemption can be obtained may determine whether this will impact the availability of veterinary care in some border regions.

Overall, more scrutiny of dog importation makes sense, particularly dogs being imported from developing countries where a variety of imported or exotic diseases may be present. However, these rule changes won’t necessarily have an impact on some of the import-associated disease problems that have occurred recently. The current changes only involve dogs imported for resale, research or veterinary treatment. Importation of dogs for research is presumably uncommon and research colonies have pretty strict rules, so I doubt there’s a lot of risk there. I also think it would be quite rare for dogs from high risk areas to be imported for research. Importation for veterinary care is also pretty uncommon and I’m not aware of it being implicated in imported disease. I don’t know how often dogs are imported for resale, and this may be the area in which these changes have the biggest potential impact. Whether a dog from a Canadian or Mexican puppy mill is any higher risk to other dogs and the public than dogs from (much more common) American puppy mills is debatable. It would be nice to see a proper risk assessment that indicates which situations are the highest risk.

Norfolk, VIrginia’s MyCityTalk.com has an article entitled "The Truth About Pet Vaccinations". It’s basically the same as hundreds or thousands of other articles available on the internet purporting to try to set the unwary pet-owning public straight about pet vaccines. Here are some of the highlights.

The evidence against vaccinating, however, is overwhelming.

  • What evidence? Someone’s commentary? Sure, there are hundreds of those. Real scientific proof? Nope. No one is going to dispute that vaccine reactions and other problems can occur. That’s clear. At the same time, vaccines clearly save lives and reduce illness. There is certainly a cost-benefit to consider, but non-evidence-based statements like this don’t help. The risks and benefits do need to be considered when designing a vaccination program. Real evidence should be used, however.

It is more and more common to see cancer in dogs and cats under 5 years of age.  Autoimmune diseases are on the rise as well.

  • Maybe, although you have to be careful interpreting that. We have much better diagnostic tests now and can detect diseases we couldn’t diagnose before. Also, animals that are alive because they didn’t die of an infectious disease are able to develop these conditions.  You cannot simply attribute such a trend to modern vaccine practices without looking at the other factors that may be involved.

Vaccinations do help prevent serious illnesses, but they should be used with restraint.  Before vaccinating, consider the risk.

  • Absolutely. Best piece of advice in the article.

If your cat is indoor only and will never be exposed to unvaccinated animals, the risk of infection is low.

  • While the risk of exposure is LOWER for indoor cats, it’s not zero. It’s amazing how many "indoor" cats come into vet clinics after being hit by a car or getting into a fight with a wild animal. Indoor cats can escape. Also, other animals can get inside, particularly bats – a source of rabies exposure.

Request individual vaccines and vaccinate at least three weeks apart if possible.

  • There’s little to no evidence that using combination vaccines is a bad thing for your average pet. Also, individual vaccines aren’t available for all diseases. Further, if you only vaccinate for one disease at a time and space them three weeks apart, it’s going to take a longer time to have an animal with protective immunity. It makes it a lot more expensive too.

If your cats go outside and you have rabies in your area, give a rabies vaccine at six months of age.

  • This sentence should start at "give."  Every animal in an area where rabies may be present must be vaccinated, regardless of whether it goes outside.

Vaccinations do not need “boosting”

  • Says who? This is a generalization that can cause problems. For some vaccines in some animals, a single dose may be adequate, but it’s certainly not true for all. Some vaccines work better than others. Some diseases are more amenable to good vaccination prevention. Some vaccines are probably good for a long time, if not life-long. But not all of them.

Simple blood tests can determine if your companion’s antibody levels for parvovirus and distemper remain high enough to resist infection.

  • Nope. You can determine antibody levels but no one really knows how to interpret them (i.e. what level means the animal will be protected). Antibodies are only one component of vaccine protection.

The currently licensed leptospira bacterins do not contain the serovars causing the majority of clinical leptospirosis today, so it is generally not a useful vaccine. 

  • That’s true for certain areas. In some regions, the vaccines strains are protective for the strains causing disease.

Homeopathic Nosodes are an alternative some guardians are using when choosing not to vaccinate. 

  • There is no evidence whatsoever that nosodes do anything but make money for people who sell them.

They (nosodes) do not produce titers against these diseases like a vaccination.

  • That’s because they don’t do anything.

Never vaccinate a sick or weakened animal.

  • Good advice.

Educate yourself.  Your veterinarian cannot make this decision for you, nor should they.  You are your companion’s guardian.  It is your responsibility to give them the best care you can by researching and carefully weighing your decisions about their healthcare.

  • That’s true. However, you need to make sure you get good advice from all sources. You should consult with your vet and feel free to ask any questions. You should also scrutinize information available on the internet. Vaccination recommendations have changed in recent years, with longer intervals between boosters, and they certainly may change further as we learn more. I’m perfectly happy stretching out vaccine intervals based on good data. My pets don’t get vaccinated every year. The key is to base decisions and changes on evidence so that we maintain the effectiveness of this critical disease-prevention tool.

The original source of the article was actually the Healthy Pet Journal, an online "journal" (site) published by a holistic/naturopathic veterinarian (who of course runs a clinic specializing in such services).  Always consider the source of what you’re reading and the potential biases that come along with it.

The latest newsletter from the University of Guelph‘s Animal Health Laboratory contains a brief update on the percentage of positive MAT tests for canine leptospirosis that the lab has seen in the first half of 2009.  Approximately 30% of the tests have been positive, which is up from the previous two years.  However, the prime time for lepto cases (and therefore typically also lepto testing) is just starting: the cool damp fall weather provides a great environment for lepto bacteria to survive outdoors for the next several weeks.

Prevention of lepto in dogs, as with most diseases, is preferred to trying to treat sick animals.  The best way to avoid the bacterium is to keep your dog out of areas where infected wildlife may urinate frequently, particularly out in the bush.  But of course, skunks and raccoons can be found as close as the backyard as well, so even in the city the risk isn’t zero.

If your dog does frequently go into the bush and is at increased risk for leptospirosis, hopefully you’ve already discussed vaccination with your veterinarian.  While the vaccine available doesn’t protect against all types of lepto, it does help protect against the most common ones – in Ontario, these are believed to be the lepto serovars grippotyphosa and pomona.  We also received the following question from a reader the other day:

"Should a dog who has shown positive for early stages of kidney disease be vaccinated against leptospirosis?  Can the vaccine accelerate the illness to acute renal failure?"

I can see where the question comes from, but the simple answer to the second part of the question is no.  Although the infection can certainly affect the animal’s renal function (and can push even healthy dogs into renal failure if it is severe), the vaccine works on the dog’s immune system and does not affect the kidneys directly.  The answer to the first part of the question is, of course, much more complicated, and depends on many other factors including the dog’s overall health status, lifestyle and other risk factors, and vaccination history.  The decision about whether or not to vaccinate your dog should be discussed on an individual basis with your veterinarian.

More information about leptospirosis is available on the Worms & Germs Resources page and in our archives.

Image: Scanning electron micrograph of Leptospira sp. bacteria (source: CDC Public Health Image Library ID#138))

A recent edition of the Veterinary Record contains a case report of Weil’s disease in a person that adopted a feral (wild) rat (Strugnell et al, 2009). Weil’s disease is a severe disease of the kidneys, liver and other body systems that can develop after acute leptospirosis (infection by Leptospira bacteria). This group of bacteria can infect a wide range of animals and is typically shed in the urine. The person that was affected adopted the rat after it was caught by her neighbour’s cat. The paper says that the rat was "urinary incontinent" – not something we usually notice about rats since they are not typically litter or house trained. I presume this means the rat was urinating frequently when out of its cage, including when it was being handled. Because of this, the owner reported that she "aimed" to wash her hands after every time she touched the rat.

A couple of weeks after adopting the rat, the woman was admitted to hospital because of lethargy, muscle aches, mild abdominal pain, cough and a bloody nose. Blood tests showed that she had decreased levels of white and red blood cells, as well as liver and kidney disease. After further testing she was diagnosed with leptospirosis. She had to be treated in the ICU, but eventually made a complete recovery. The adopted rat and the other rat that she owned were euthanized by the owner’s partner shortly after she was admitted to hospital. Testing of the adopted rat identified Leptospira in the kidneys.

This is another example of why wild animals should be left in the wild, and another case highlighting the need for veterinarians, physicians and public health personnel to work together.

More information on Leptospira and leptospirosis can be found on the Worms & Germs Resources page and in our archives.

Molly is a 1-year-old Labrador Retriever (not mine!) that has a peeing problem. She often urinates in the house when she’s excited, which raises the question about how to clean up such accidents.

In general, urine is sterile and is not a risk for disease transmission. Simply removing urine from the area should therefore be adequate. However, urinary tract infections can happen, and some of the bacteria that cause these infections could be transmitted to people, although the risk is likely extremely low. The risk is probably greatest in pets that develop repeated urinary tract infections because of underlying diseases such as diabetes. Another concern is leptospirosis, a bacterial infection that can cause kidney failure and that can be transmitted to people.  More information on leptospirosis is available on the Worms & Germs Resources page.

In most situations, indoor urination is more of an annoyance than a real health risk. If a pet suddenly starts urinating in the house, it should be examined by a vet to look for any of the many health or behavioural problems that can cause this. This includes testing for a urinary tract infection. If an infection is present, or a pet has suddenly started urinating in the house for an unknown reason, it is prudent to be more careful about cleaning it up than one might be when dealing with housetraining accidents in puppies, or with dogs with certain chronic urination problems not related to infection.

Urine should be removed with disposable paper towels, which are promptly discarded. The area should also be disinfected, if possible. Smooth surfaces (e.g. linoleum, tile, hardwood) can be wiped with any appropriate household disinfectant. Carpets are harder (if not impossible) to disinfect. Always wash your hands after cleaning up any accidents.

The warm weather is just about here, and that means the start of camping season. Lots of people love to spend time in the great outdoors during the summer, whether it’s at a summer cottage on the lake, trailer camping in a park with electricity and running water, or roughing it in a tent in the peace and solitude of a more remote wooded location. And many people bring along their faithful companions – their dogs – who enjoy the experience just as much, if not more, than we do.

But there are also dangers lurking in the forests – microscopic dangers carried by tiny insects and other bugs. Ticks in particular are problematic. Certain ticks can carry a number of diseases that can make dogs sick, including Lyme disease (caused by Borrelia burgdorferi) and Rocky Mountain Spotted Fever (RMSF)(caused by Rickettsia rickettsii ). Both Lyme disease and RMSF are more common in certain areas where the tick species that carry them are present.  You can NOT catch these diseases from your dog, but both you and your dog can be infected by the ticks that carry them. People can also be exposed to these pathogens by accidentally crushing an infected tick while trying to remove it from their dog. Ticks must be removed very carefully to ensure that the entire tick is removed, including the head and mouth pieces, without crushing it. If you’re not sure how, contact your veterinarian.  Also, the sooner the tick is removed, the less likely it is to transmit certain diseases, so be sure to check your dog thoroughly for ticks when you come back from a walk in the bush.

The Minnesota Department of Health recently reported that the number of cases of (human) Lyme disease increased in that state in 2007. This could be because of spreading tick populations, more people participating in activities in tick-inhabited areas, or increasing awareness and diagnosis of the disease by physicians.

If you and your canine companion will be spending time in some of the wilder and woodier parts of the great outdoors, talk to your veterinarian about what you can do to protect your dog. There are vaccines available for Lyme disease and the bacterial infection leptospirosis (which is also transmissible to people). Flea and tick preventatives are also very important, and many of today’s products are very effective. People should always wear insect repellent when camping or hiking in the woods. Visit the Health Canada website for safety tips on using personal insect repellents. All dogs should be vaccinated for rabies, whether they go camping in the backwoods or they’re house-bound city-slickers.