Search results for: lepto

Leptospirosis is a bacterial infection that’s been described as a re-emerging problem in dogs in North America. (It’s been described as that for many years now so maybe we should drop the "re-emerging" and just say it’s a problem). The causative agent, Leptospira interogans, is a widespread bug that’s carried by a variety of wildlife species, and it can cause disease in many different animals, including dogs and people.

In dogs, lepto is an important cause of kidney disease in some regions, and infected dogs pose some degree of risk to people who come in contact with their urine. While it used to be mainly associated with rural dogs here in Ontario, it’s increasingly being found in urban dogs because of the proliferation of raccoons (that can shed the bacterium in their urine) in cities.

A recent study from the University of California Davis (Hennebelle et al, Risk factors associated with leptospirosis in dogs from northern California: 2001-2010, Vector Borne and Zoonotic Diseases, 2014) looked at 67 dogs with lepto and 271 non-lepto controls. You can’t extrapolate all the results to other regions, because there are different animal reservoirs and other factors to consider, but the study provides some good information.

Here are the highlights:

  • Vomiting, lethargy, increased white blood cell count and increased kidney values (azotemia) were the most common presenting problems. That’s not surprising but it’s a constant problem. Dogs don’t come in screaming “I have lepto!!!” They often have vague signs and it may be a little while (and a lot of handling) before lepto is considered or diagnosed. That in-between period poses a risk to handlers if good practices to avoid urine contact aren’t used, so practicing good general infection control and keeping lepto under consideration in any of these cases are important to reduce human risks.
  • Dogs with lepto can be pretty sick and treatment can be pretty expensive. On average, affected dogs were hospitalized for 11 days at a cost of $5459 (USD). This doesn’t mean it’s always this expensive. This is a referral hospital that probably sees a caseload that’s sicker than average, but regardless, it’s a serious and often very expensive disease.
  • 13% of affected dogs died. Again, that’s based on a biased caseload, but still shows it’s not to be taken lightly.
  • The main serovar was Pomona. That’s different than we see here in Ontario, where Grippotyphosa (mainly from raccoons) predominates.
  • There were regional differences even in California, with more cases from the central or south coast, Sierra Nevada foothills, San Francisco bay area or north coast compared to the distribution of control dogs.
  • Owners of dogs with lepto were more likely to report that their dog had contact with water or wildlife, or visited a ranch. These are risk factors for lepto that have been found in other studies as well, and make sense biologically.
  • Other risk factors included being 5-10 years of age or over 10 years of age, or being hound breeds.

Lepto’s a big problem in many regions, including around here. That’s why my dog Merlin’s vaccinated against the disease. Lepto vaccines have gotten a bad rap because the older ones were relatively ineffective and associated with increased risk of adverse reactions. However, today’s vaccines protect against the important strains (for most regions) and are quite safe. Discussing the risk of lepto and whether vaccination is indicated is something every dog owner should do with their veterinarian. Knowing regional trends in lepto help make that determination.

Some information about lepto distribution in dogs is available at http://www.wormsandgermsmap.com We don’t have a lot of cases entered yet, so more data would help.  If you are a veterinarian or veterinary technician and would like to know how you can help contribute data, click here.

Studies that look at risk factors can be pretty variable in terms of what they tell you, the impact they have and how accurate they are.

Some findings are pretty logical, clear and indicate something that should be done.

  • Smoking is a risk factor for [insert many diseases here], so to reduce the risk of [whatever disease], stop smoking.

Others make sense but don’t necessarily lend themselves to an effective intervention.

  • Being male is a risk factor for cardiovascular disease… not much I can do about that.

Sometimes, you have to remember that a risk factor for one thing doesn’t provide a clear answer when a broader context is considered.

  • Moderate consumption of red wine can reduce the risk of various conditions, but alcohol consumption can also increase the risk of other conditions.

Sometimes, how the study is designed and performed can really affect the results.

  • If I did a large study of the general population in Guelph, I could presumably show that going to a hospital greatly increases your risk of death. Does that mean you shouldn’t go to the hospital? No, because I could presumably also show that if you have chest pain and go to a hospital, you’re more likely to live. Knowing the study population and what question is really being asked are critical.

Sometimes, something that’s found to be a risk factor isn’t really the risk factor, but it’s associated with something else that is.

Sometimes, something can be "statistically significant," but of limited consequence.

  • If doing something increases the risk significantly, but only by 0.0001%, does that mean anything?

Why do I write this? Because these are some of the things that we have to think about when assessing risk factor studies. While one Toronto radio station loves to give 10 second snippets on some new risk factor medical study, you can’t determine much about the study itself from a sound-bite (or internet post). You need to think about the details regarding how the study was done. Nevertheless, risk factor studies can provide useful information, but consider the results carefully, whether they are relevant, whether they indicate changes need to be made or whether they indicate that we need to look at the issue further.

Anyway, this rambling post was prompted by a couple of papers looking at risk factors the leptospirosis in dogs (Hennebelle et al J Am Vet Med Assoc 2013 and Raghavan et al Prev Vet Med 2012)

The first study compared dogs from northern California that had or didn’t have leptospirosis. They found a few things:

  • There were differences in geographic distribution of the lepto cases and controls. That makes sense since we know lepto varies regionally, but living in different areas might also be associated with different behaviours and contacts (e.g. wildlife contacts).
  • There was a temporal cluster, with more cases occurring between May 2003 and May 2004, compared to the rest of the 2001-2010 study period. That makes sense too since we see variation in cases within and between years.
  • These results don’t change anything, but are an indication of what work needs to be done next. Looking at why things vary geographically and temporally might be important for figuring out how to reduce the risk of disease. It also indicates regions where more efforts to educate pet owners (and veterinarians) are indicated, and where vaccination is more important.

The second study looked at dogs from Kansas and Nebraska, with and without leptospirosis. They also found a few risk factors.

  • Lepto was more common in houses lacking complete plumbing facilities. Presumably, this is a proxy for something else. Poor plumbing doesn’t likely result in lepto in dogs. Rather, it presumably means that a dog living in a house with poor plumbing has some other factor that increases its risk. For example, incomplete plumbing may be more likely in lower socioeconomic (i.e. lower income) households, which might then correspond to other more direct risk factors for the dog (e.g. poorer nutrition, less veterinary care). It could also be that houses lacking complete plumbing tend to be in a different area where there’s more exposure to wildlife reservoirs. A couple of other indicators of poverty status were also significant, highlighting the potential impact of owner poverty on pet health.
  • Dogs that lived within 2500 m of a university or college, or a park, were also at increased risk. The park risk factor makes sense since they could be exposed to sites infected by wildlife reservoirs (e.g. raccoons). Living close to a university or college is tougher to figure out. Maybe it’s associated with economy, as students are typically at lower income levels. Maybe it’s because colleges and universities usually have lots of green space that might harbor wildlife.

So, these studies tell us some new information, reinforce some previous knowledge (or perceptions) and raise some new questions that we need to answer. By themselves, they won’t result in major changes in how we try to prevent lepto in dogs, but little steps is typically how science progresses.

Life with Merlin has been busy but going pretty well. There’s been no pee on the floor in the past 48 hours so we’re making progress. Speaking of pee (which, sadly, I seem to do a lot), we need to decide about leptospirosis vaccination for Merlin.

A good preventive medicine program is important for every pet. There’s no "one size fits all" version – the program needs to be tailored for every region and pet/owner combination. We have Merlin’s deworming covered. I gave him a booster vaccine the other day, which covers distemper, parvo and a couple of respiratory viruses (adenovirus type 2 and parainfluenza). Rabies vaccination will be coming soon, when he’s a bit older (at least 3 months). Now that we have the "core" components covered, we need to think about the elective aspects. One of those is vaccination against leptospirosis.

When thinking about vaccination, it’s a cost-benefit decision. The costs and benefits can be hard to accurately assess, but a few basic questions are key: Is there a risk of exposure? Is the disease of concern? Is there a safe and effective vaccine?

Is there a risk of exposure?

Leptospirosis, a potentially life-threatening infection caused by different types of Leptospira bacteria, has been called a "re-emerging" disease in many parts of North America since rates of infection have increased over the last 20 or so years.

Leptospirosis certainly occurs in dogs around here. We don’t see a lot of cases but it’s far from rare and it can be nasty.

Wildlife are the main reservoir. Infected wildlife shed the bacterium in their urine, and urine-contaminated water and wet areas are the main sources of infection. Raccoons are the biggest concern around here, and there is certainly no shortage of raccoons around my house (including in the garage sometimes). Since Merlin is a Labrador, he’s bound to spend a lot of time swimming in ponds and wallowing around in wet areas on our property… prime sites to be contaminated by pee from infected wildlife. So, there’s a reasonable chance that he’ll be exposed.

Is the disease of concern?

There’s no doubt here. While it’s uncommon, it can be nasty. Life-threatening infections can occur and kidney failure is a major problem. Treatment of lepto can be difficult and expensive.

Is there a safe and effective vaccine?

Lepto vaccines have had a bad rap. Older vaccines weren’t very effective (often not protecting against the strains that are of concern) and were associated with a high rate of adverse reactions. Those former concerns have persisted in some people despite the fact that there’s a new generation of vaccines that are much more effective and safer. The new vaccines are better designed, better tested and cover a broader range of strains. There’s quality research indicating that they work. Like any vaccine, they’re not 100% effective but they are quite good overall.

Information about adverse reactions is harder to get. Adverse event reporting is sporadic at best, but the available information doesn’t indicate that these vaccines cause a greater incidence of adverse reactions than any other vaccine. Any given vaccine can cause a problem in any given dog, but the overall risk is low.

So, don’t tell Merlin but another set of vaccines is in his future.

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)

Leptospirosis is disease caused by several types of Leptospira bacteria. It’s often called a re-emerging disease in dogs, because the incidence has been increasing over the past couple of decades in many areas. While the overall number of infections is limited, when it does occur lepto can cause serious disease, including kidney failure. It’s also a zoonotic disease: lepto can be transmitted from sick dogs to the people who handle them. Infected animals shed the bacteria in their urine, and when the urine comes in contact with broken skin or mucous membranes (mouth, eyes, nose), transmission of infection can result.

Canine vaccines against lepto are available. In the past, lepto vaccination hasn’t been all that popular because the vaccines tended to have a higher rate of side effects compared to most vaccines, and the types of lepto that the vaccines targeted were often not the most important types causing disease. This has changed more recently as newer vaccines have become available. These vaccines seem to have low rates of adverse effects and provide protection against the four types of lepto that tend to be the most important. These vaccines have also been shown in research studies to protect against disease and to reduce shedding of the lepto bacterium in urine (thereby decreasing the risk of transmission to other animals or people).

Lepto is not among the "core" vaccines that groups say all dogs should have. That’s because the risk of lepto exposure varies greatly between regions and dogs. The key thing to consider when deciding whether or not to vaccinate is what each individual dog’s risk of exposure is. The main reservoir of lepto is wildlife such as rats and raccoons. If infected wildlife are in the area, they may be peeing out lepto and contaminating the environment, particularly any type of standing water (lepto loves to live in warm, wet environments).

In the past, much of the concern has been focused on dogs that go out and swim in streams or ponds.  The "poster child" for lepto has typically been the Labrador Retriever that goes out gallivanting in the bush, but that may be changing too.  When you consider where wildlife such as rats and raccoons live and how high the wildlife infection rates can be, remember that these pests can be present in urban areas in incredibly large numbers.  Living in a city does not make a dog safe from exposure to lepto. In fact some urban areas, with large numbers of wildlife crowded into high-traffic areas like parks, are probably higher risk than rural areas.

Deciding on vaccinating requires an understanding of how common lepto is in the area and whether there is a risk of exposure for the individual animal. This is a disease for which a veterinarian’s understanding of disease patterns in an area (including any specific areas that be particularly high risk) and the types of possible exposure of the dog play a big role. There’s no "one size fits all" recommendation for lepto vaccination.

British champion rower Andy Holmes has died of leptospirosis, which was suspected to have been acquired from the water during the annual Boston Rowing Marathon on the River Witham (UK) in September. The 51-year-old Holmes, an accomplished Olympic rower from the 1980s, started to feel unwell in the days after the race, and developed a fever. He was subsequently diagnosed with Weil’s disease, a serious form of leptospirosis that can cause liver failure.

In some ways, this is being written off as a very rare and unfortunate event. It’s always hard to determine how aggressive to be when making recommendations about avoiding infections that can be acquired from common recreational and occupational activities.

The race’s welfare officer stated "Part of any rower’s training is being warned about water safety. If you fall into water you must wash thoroughly and if you think you have ingested any water seek medical advice." The problem is, exposure to water during rowing and similar events is basically unavoidable. Splashes of small amounts of water into the eyes, nose, mouth or cuts/scrapes could be enough to inoculate potentially harmful microorganisms into the tissues. People aren’t going to run to the physician after every potential exposure. Knowing whether or not the water source has previously been implicated in leptospirosis infections may be useful, but it doesn’t tell you anything for certain.

General recommendations for people working around water include:

  • Covering cuts and sores with waterproof bandages.
  • Washing hands, particularly before eating.
  • Avoiding contact of water with the eyes, mouth and nose, whenever possible.
  • Avoiding ingestion of any amount of water.
  • Ensuring their physician knows about the potential for water exposure should they become sick.

Obviously, complete avoidance of water exposure is impossible for many people, and the overall risk is very low. Weil’s disease is a rare condition but it does occur, both as sporadic cases and large outbreaks. It’s usually treatable but can be fatal, so it shouldn’t be dismissed.

Issues with pets and leptospirosis are similar. Pets, mainly dogs, become exposed from contact with water that has been infected by Leptospira bacteria from the urine of infected wildlife.  Infection can cause a broad range of disease in dogs as well, from subclinical to acutely fatal.  Vaccines for certain strains are available for dogs who are at higher risk of exposure.  Talk to your veterinarian about whether your dog should be vaccinated against leptospirosis.  More information about leptospirosis in dogs and cats is available on the Worms & Germs Resources page.

Image: Andy Holmes sits behind Steve Redgrave after winning a gold medal for Britain at the 1988 Seoul Olympics.

Veterinarians are reporting a potential cluster of leptospirosis cases in dogs near Lake Aquitaine in Mississauga (Winston Churchill Blvd. & Derry Rd. area). Leptospira gryppotyphosa has been confirmed in one dog, with other cases being suspected but not confirmed because owners declined testing.

Leptospirosis is a bacterial infection caused by different types Leptospira spp. These bacteria like to live in water and in moist conditions, and infections in dogs most often result in kidney disease. The bacterium is shed in the urine of infected animals. Leptospira gryppotyphosa is mainly found in wild voles, raccoons, skunks and opossums, and these animals can infect various environmental areas. Any animals exposed to outdoor environments in endemic areas can become infected from ingesting infected water or from contact of infected water with the mouth, eyes or nose, or cuts or other broken skin.

People in the area where these cases have been found should take particular care and probably avoid letting their animals wander into the water or wet areas. A vaccine is available to reduce the risk of leptospirosis, including disease caused by this Leptospira type. Vaccination of pets that are exposed to water or wet habitats in areas where lepto is present is a good idea. People in the Lake Aquitaine area should be particularly vigilant and vaccination of pets would be a good idea.

(click image for source)

Veterinarians are reporting an apparent spike in cases of leptospirosis in dogs in southern Michigan. Leptospirosis is considered a re-emerging disease in many areas of North America. This disease, caused by various types of the Leptospira bacterium, can affect many different species, including dogs and people. A wide range of illnesses can result, including fatal infections. In dogs, kidney failure is a common problem. 

Classically, leptospirosis is diagnosed in dogs that spend time in the woods and similar areas, where they may be exposed to the bacterium from contact with the urine of infected wildlife. Different types of Leptospira have different animal hosts, and infected hosts can shed large numbers of bacteria in urine. These bacteria can survive in wet conditions for long periods of time, and other animals can be infected through ingestion of urine-contaminated water or contact of urine-contaminated water with broken skin (e.g. tiny cuts or open sores on their feet) or mucous membranes (eyes, mouth, nose).

Michigan vets have suggested that the recent spike in cases is the result of local highway construction, which may have driven rats out of their normal habitats and into areas that people and dogs frequent. That’s possible, but it could also be increasing natural re-emergence of the disease, or increasing recognition of the disease, as more attention is being paid to it. Regardless, an understanding that this disease is a problem in the area is important to allow for prompt diagnosis (and proper treatment), as well as preventive measures.

A vaccine is available, but it is not 100% protective and only protects against certain strains of Leptospira. Nonetheless, it’s still a good idea in areas where disease is caused by the strains present in the vaccine and when dogs have a reasonable chance of being exposed.

People can also get leptospirosis. Most often, they are exposed just like dogs: from the outdoor environment. However, pet-to-human transmission has been reported, mainly involving pet rats (since rats are an important reservoir host). People who have contact with an infected dog must take precautions to reduce the risk of transmission. This includes avoiding contact with urine, good attention to personal hygiene (especially hand washing), and proper cleaning and disinfection of any areas potentially contaminated with urine. Prompt diagnosis of canine lepto is very important because treatment rapidly stops the animal from shedding the bacterium. The earlier it’s diagnosed, the quicker it can be treated, and the less contamination can occur.

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

(photo by costi)

When we have a -30C windchill and snow on the ground, my first thoughts usually aren’t about survival of bacteria in the outdoor environment. However, some microorganisms are well adapted for survival in various adverse conditions and we shouldn’t assume that cold=dead for every bug of concern. Along that line, we received a question recently about survival of Leptospira and I passed it along to our lepto expert, Dr. John Prescott. Here’s his guest post:

A reader in Ohio owns a dog that had leptospirosis, and had some questions about leptospirosis that may be of general interest.

Q1. Since the yard is likely contaminated with leptospires, she asked “How cold does the temperature have to get before the Lepto organisms are killed?”

A1. Once it’s frozen, as it is now in January, they’re dead. Leptospires are fragile bacteria that are killed by dry heat and by freezing. They survive well in moist or wet environments, with moderate temperatures. In some countries leptospirosis is called “mud fever” or “fall fever” since this description captures so well the environmental conditions under which they thrive.

Although leptospirosis in dogs can occur at any time in the year, it mainly causes disease in the fall, late September to December, peaking in November. The increasingly mild and prolonged falls that we have experienced in the last decade are thought to be an important reason that leptospirosis has resurged in dogs. Interestingly, there is often a “blip” of leptospirosis in dogs in March in Ontario (and likely Ohio), since this is when the snow melts and conditions are wet, even though we can still get freezing at that time. I suspect that this is also the time when the raccoons that are thought to be the main source of leptospirosis for dogs are again active after the winter, and are foraging for food for themselves and their babies.

Q2. Do dogs still shed leptospires after they’ve been treated?

A2. No. Leptospires are quickly killed by the antibiotics used in treatment, amoxicillin or doxycycline. There is no danger that dogs treated for a week with these drugs are a risk to people or other animals. You may read in otherwise very reputable textbooks that these antibiotics “do not eliminate the carrier state” but I have no idea where this misunderstanding comes from.

Q3. Where can I find out more about leptospirosis in dogs?

A3. I like the web site http://www.leptoinfo.com, which is maintained by a vaccine company. I was surprised how many web sites devoted to leptospirosis that there are, but like much on the internet some contain highly misleading information. The “Worms & Germs” site has good past blogs about canine leptospirosis and is usually (just kidding, Scott) a reliable source of information.

One very common entrenched misconception, which is very hard to kill, is that vaccination does not stop animals shedding the organism. This is quite wrong. I suspect this misconception came from an experimental study half a century ago when dogs with pre-existing kidney infection with a leptospiral serovar called Canicola were vaccinated. It would not be expected by anyone that these animals would stop shedding since antibodies don’t penetrate into the place in the kidney where the leptospires live and from which they are shed in the urine. What vaccination does incredibly effectively is to prevent leptospires from actually reaching the kidney and setting up home there. The leptospires are removed by antibodies in the blood, so they never reach the kidney.

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))