Worms & Germs Blog

Not all bugs must die…subclinical bacteriuria in cats

Posted in Cats

Tabby catSince we developed the first version of the ISCAID guidelines for diagnosis and management of urinary tract infections in dogs and cats in 2011 (revision currently underway), most discussion about them has probably revolved around our recommendations for animals with subclinical bacteriuria. In this condition, an animal has bacteria in the urine, but no signs of disease. Traditionally, these cases were classified as urinary tract “infections”, and treated with antibiotics. Yet, we know that a reasonable number of dogs and cats (and people) have bacteria in their bladder at any time, and it doesn’t cause any problems. The condition occurs at higher rates in certain groups (e.g. diabetics, elderly females). While bacteria can cause true urinary tract infections (UTIs), we don’t have evidence that subclinical bacteriuria is actually an issue for the animal (or person), either by itself or as a risk factor for development of UTI or other complications. However, a lot of antibiotics are used to treat this “problem” that probably really isn’t one. In people, a lot of time and effort has gone into reducing unnecessary treatment of asymptomatic bacteriuria (the human equivalent of subclinical bacteriuria in animals). In veterinary medicine, it’s been a tougher battle.

A lot of animals with subclinical bacteriuria still get treated, for a few reasons. One is difficulty accepting that the bladder isn’t always sterile (since that’s what most people have been taught), and that having bacteria there isn’t rare. There’s also the fear that it could lead to the development of other problems, even though evidence indicating a health risk is lacking.

The situation is definitely improving though. While I still get a lot a comments about people not being willing or able to withhold treatment, more and more veterinarians are no longer prescribing antibiotics for these cases. It can be scary at the start, but once they start holding off on treatment, they realize it doesn’t cause any harm, and that usually converts them. I probably get more comments now about how our guidelines should be stricter, as opposed to complaints about the recommendation that treatment isn’t needed.

It’s a small research field, but more supporting information continues to trickle in, including an article in the most recent edition of the Journal of Veterinary Internal Medicine (White et al 2016).  Here’s a brief summary of the highlights:

  • Researchers looked at 67 cats at five time points over 3 years.
  • Urine was collected, along with various health and laboratory data.
  • Overall, bacteria were present in the urine of 9.8-12.7% of cats over the 5 timepoints. In some, bacterial counts were very high, and 6 female cats were repeatedly positive.
  • Female cats over 7 years of age were at highest risk of bacteriuria. However, signs consistent with a urinary tract infection were only identified in 0-2 cats at each timepoint.
  • The presence of bacteriuria was not associated with death during the study period (i.e. it did not affect the cats’ survival).

The report ends with a nice conclusion: “…[Subclinical bacteriuria, SB] is common in older, nonazotemic cats at a similar prevalence to previous studies of cats with hyperthyroidism and diabetes mellitus. Cats in our study were nonazotemic, and some cats were euthanized for progressive weight loss associated with chronic conditions often treated in private practice. Among this cohort of cats, SB was not associated with body weight, azotemia, the development of CKD [chronic kidney disease] at necropsy, or overall survival. These findings are consistent with large studies in people and suggest that treatment of SB in the absence of risk factors for urosepsis or urogenital disease may be unnecessary.”

Raccoon Rabies – 1 Year Later

Posted in Rabies

Rabies_Surveillance_and_Control_11_30_2016It has been just over 1 year since the discovery of the first rabid raccoon in Ontario in over a decade, and the first rabid wildlife in the Hamilton area in over two decades.  Since then well over 4500 abnormal or “found dead” wildlife have been tested, and 253 animals carrying raccoon-variant rabies have been found in Hamilton and the surrounding areas (see map).  To see more maps of how the outbreak has progressed, visit the OMAFRA rabies website and click the first link “OMNRF Wildlife Rabies Control Zone“.  The raccoon variant has been found in 175 raccoons, 76 skunks, 1 red fox and 1 stray cat.  There have been no human cases and no confirmed domestic animal cases (not counting the stray cat) associated with the outbreak, but there has been lots of effort on the part of the local public health units to provide post-exposure prophylaxis to potentially exposed people, and local veterinarians have been working with owners to ensure pets are vaccinated, and with OMAFRA when needed to arrange testing of suspect animals and confinement of exposed animals that were not properly vaccinated.  The MNRF has also dropped over 1.6 million oral rabies vaccine (ORV) baits in southern Ontario to help contain the spread of the virus.

In addition, almost 30 rabid bats have been detected from all over southern Ontario, and one rabid skunk was found to be carrying bat-variant rabies as well.

Two weeks ago a rabid cow was found in Perth County, but the cow had fox-variant rabies, similar to another cow in December 2015 and a skunk in March 2016 from the same region.  Based on these cases we know that fox-variant rabies is still circulating in the area (at a very low level), even though no cases were detected for 3 years prior to December 2015.  These cases are not related to the raccoon-variant cases in the Hamilton area.

The take-home message is that rabies is still alive and well in Ontario, but veterinarians, public health, OMAFRA and the MNRF are all working hard to protect people and domestic animals from this deadly zoonotic virus.  It is critical for members of the public and animals owners to do their part as well, including:

  • Avoid direct contact with wildlife (including bats) or animals that are behaving abnormally.
  • Vaccinate pets and livestock that may be at high risk of exposure (or that may travel or have contact with a lot of different people, such as show or competition animals).
  • Report any human exposure to saliva of a potentially rabid animal to the local public health unit, or a physician.
  • Report exposure of any pet or livestock to a potentially rabid animal to your veterinarian so a risk assessment can be performed.
  • Live wild animals that are in distress or acting in a threatening manner should be reported to local animal control, if available, or the local police as a last resort.

Ontario lungworm update

Posted in Dogs, Parasites

The fox lungworm, Crenosoma vulpis, continues to be identified in dogs in Ontario. The attached map from WormsAndGermsMap shows the cases we know about. There aren’t many, but the issue of “rare vs rarely diagnosed” is important. As a relatively new (or newly identified) problem that requires specific testing, it’s easy for it to be overlooked. The distribution on the map shows how widely lungworm cases have been spread across the province.

Lungworm is a possible cause of chronic cough dogs in areas where the parasite is present. That now includes much of Ontario. Readily treatable, it’s important that lungworm testing is considered in cases of chronic respiratory disease, particularly those that have not been recently or routinely treated with antiparasitics that are effective against lungworms.

WormsAndGermsMap

All you wanted to know about Baylisascaris…the raccoon roundworm

Posted in Other animals, Parasites

Large raccoonThe US Geological Service isn’t the first thing that comes to mind when I think about publishers of zoonotic disease information (but what do I know?).

If you’re looking for some holiday reading, the USGS has published a comprehensive overview of Baylisascaris larva migrans, a serious disease caused by Baylisascaris procyonis, the raccoon roundworm. This parasite is very common in raccoons, which carry the adult worms in their intestines and shed the eggs in their feces.  In contrast, human infections caused by the immature larvae are rare, but they can be devastating. The publication is authored by Dr. Kevin Kazacos, someone who’s been at the forefront in this research field, and contains pretty much everything you’d want to know about this parasite, and more.

Pre-multidrug-resistant TB in a dog

Posted in Dogs, Other diseases

Dog on leash2A few times a year I get questions about tuberculosis (TB) in dogs, typically after a person is diagnosed with active TB and people want to know what the risks are to, and from, their dog. It’s often tough to answer those questions, because there’s limited information available. Risks exist, but how much of a risk and how to assess that risk are difficult figure out.

A recent paper doesn’t answer all the questions but provides some more insight. The short communication in Transboundary and Emerging Diseases (Ribeiro et al 2016) describes a fatal case of tuberculosis in a dog. That’s interesting by itself, since TB infection in dogs is pretty rare, even in dogs with long-term contact with infected people. Another twist to the case is that the dog was infected with a strain of Mycobacterium tuberculosis that was resistant to some important anti-TB drugs.

Here are some of the highlights:

  • The two-year-old dog had a history of bloody stools and weight loss over the preceding eight months. The dog’s owner had been treated for over six months for TB.
  • Among other things, examination of the dog at the time of presentation identified thickening of the intestinal tract. An intestinal biopsy was taken and acid fast bacilli consistent with M. tuberculosis were identified. A fecal culture subsequently confirmed the identity of the bacterium.
  • The dog died shortly after the diagnosis (but probably would have been euthanized shortly thereafter regardless on the recommendation of public health officials).
  • Subsequent testing of the bacterial strain determined that it was resistant to a variety of drugs that are used to treat TB in people: isoniazid, ethambutol, ciprofloxacin, ofloxacin, streptomycin and amikacin. This places it in the “pre-multidrug resistant” category.

This case raises a few questions:

Where did the TB come from?

This one’s easy. It almost certainly came from close and prolonged contact with the owner. TB is not readily transmissible with transient contact, but living in a household with close contact is a high-risk factor for people, and that would probably apply at least to some degree to their pets too.

Why did this dog get TB?

That’s a tougher question. TB is rarely diagnosed in dogs owned by TB patients, even when they have had long-term, close contact. Whether this dog had some underlying problem that made it more susceptible to infection, the owner was shedding particularly large numbers of the bacterium, or it was simply bad luck (or a combination of these factors) isn’t known.

Does rare really mean rare?

Good question. We rarely identify TB in dogs, but does that mean it rarely occurs, or it’s rarely identified?  We don’t really know.

Why don’t we know much about TB in dogs?

There are few people who work in companion animal infectious diseases, so not a lot of study has been done in this area. TB isn’t a major health problem in dogs, so it’s hard to find money from canine groups to do that type of research. TB in dogs is a pretty oddball phenomenon for human healthcare funding to pay much attention to it. I’ve had a good study of TB in dogs in mind for a while, but it would be exceptionally difficult to get it funded.

Another problem is testing. Screening tests used in people like the tuberculin skin test and IGRA are not useful in dogs. So, we don’t have an easy, readily accessible test in this species. Diagnosing active TB including shedding of the bacterium is even more difficult. Unlike people, where sputum samples are easily collected and tested, getting a good respiratory sample from a dog is more of a challenge. Furthermore, TB may be more of a gastrointestinal issue in dogs (vs respiratory), so we don’t know the optimal testing approach.

Is euthanasia indicated if a dog has TB?

This dog died, and euthanasia in advance of that would probably have been justifiable based on its severe disease. The question that comes up in other cases is what to do with a dog that might have TB but isn’t very sick. TB is potentially treatable, but it requires long-term treatment with combinations of drugs, and we don’t have any evidence to to tell us what the optimal treatment regimen in dogs is. There’s also concern about human exposure during treatment and the (very unlikely but possible) emergence of resistance during treatment of the dog.

This case raises a similar issue, since the dog was infected with a strain that was already resistant to a variety of antibiotics, which is a very serious public health concern, and which would increase the support for euthanasia (based both on the inability to treat the dog effectively and concern about dissemination of this very concerning resistant strain).

TB is one of the most common and important infectious diseases in humans globally, and it’s a disease that is getting more problematic over time. Questions about what to do with exposed dogs are important to address, and more information is needed about the risks to and from pets to make sure we can handle these situations as effectively as possible.

American Family Physician: Enhancing Patient Care Through Time with Animals

Posted in Dogs

dog-walkingHere’s a case scenario in a “Curbside Commentary” from the journal American Family Physician (Mani and Weese, 2016).

A 16-year-old girl and her parents presented to my office for her wellness evaluation. The patient has generalized anxiety disorder with comorbid major depression, for which she has been prescribed a serotonergic antidepressant. She is a high school student, lives with her parents, and is currently preparing college applications. She has occasional headaches and disturbed sleep. She takes daily three-mile walks and plays on her school tennis team, both of which help relieve her anxiety symptoms. The therapist she sees once a week has suggested enrollment in a therapeutic foster dog walking program to help further relieve her anxiety symptoms.

Would animal-assisted therapy be helpful as a part of anxiety and depression management in this patient? Would such treatment be a helpful approach for other teenaged patients in my practice with similar diagnoses?

Check out the full article for the commentary.

Brucella canis and rescue programs

Posted in Dogs

boxer-puppyA Wisconsin rescue has its dog population under quarantine after a dog that was adopted from the facility was identified as being infected with Brucella canis. Dogs at Gregory’s Gift of Hope are being tested, and any positives will presumably be euthanized. Littermates of the infected dog, which was adopted in 2015, are being traced for testing. Canine brucellosis is a major concern because of the potential transmission to people and the fact that dogs can be infected for life. These situations are pretty awful overall because of the timeframes involved. If any of the littermates are positive, there’s been potential exposure of people for a while (although spaying or neutering profoundly decreases the risk). Further, it’s heartbreaking when dogs that have been in the household and have never looked sick are identified as positive, and may be euthanized.

A big problem with canine brucellosis is the fact that infected dogs don’t look sick. The dogs may have reproductive problems, but most dogs are not breeding animals and in those that are, reproductive problems often aren’t adequately investigated to determine the cause. The typical approach to control is to euthanize infected dogs, and to consider all in-contact dogs as exposed and to test them (usually twice, 30 days apart).

In a related note, Wisconsin’s State Veterinarian, Dr. Paul McGraw, issued a special order requiring brucellosis testing of “auction dogs” in September. All dogs sold at auction in the state must now have a negative brucellosis test within the past 30 days.  There have been 18 confirmed cases in canine brucellosis in the state since 2011, a low number but probably an underestimate because of limited testing. The new measure is a good start, but it’s hard to say how effective it will be. That would require knowing more about those 18 cases and about Brucella canis transmission, in general.

It’s a bit concerning that one shelter veterinarian stated “We do get dogs from out of state, often unaltered [i.e. not spayed or neutered], but they are not obtained at an auction. We transfer dogs from overpopulated shelters and have been working closely with these shelters for some time. We feel confident that these dogs have not been purchased from auction.”  That misses the point. Auctions aren’t the only source of infected dogs, they’re simply one high-risk source and one that is more easily regulated. Shelters that import dogs from the southern US, in particular, risk importing infected dogs. Those animals don’t go through an auction system so they are not captured under the new order, but shelters shouldn’t assume that means the dogs are not at risk. Testing all dogs in shelters isn’t practical, but testing high-risk dogs (e.g. dogs from areas where the disease in common, dogs imported from other countries) would be more practical and would make a lot of sense.

Dog Licks…Again

Posted in Dogs, Other diseases

Every year or so, there’s a new wave of publicity/paranoia about the risks associated with dogs licking people. Often, it follows a study of bacteria that can be found in the mouths of dogs. It leads to a combination of balanced reports, sensational reports and defensive responses.

What is the concern?

Dog’s mouths are vats of billions of bacteria from thousands of different species. Some of those species can cause disease in people. Licking can be an effective way to transfer some of these bacteria to people.

What is the real risk?

That’s the tough question. Dogs lick people all the time. Very few people get sick. Every dog has something in its mouth that could kill a person in the right situation. The same could be said of every person’s mouth (as well as lots of door knobs and other surfaces we touch all the time). We get exposed to disease-causing bacteria incredibly often… probably multiple times a day at least.

The overall risk of disease from a dog lick is low, but there is some risk and it’s wise not to ignore it.

Risk reduction is the key.

Are some situations riskier than others?

Yes. The implications of exposure to bacteria in dog saliva are higher in some groups, namely:

  • People who have compromised immune systems
  • People who don’t have a spleen (that’s related to immunocompromise but is a noteworthy group because of the risk posed by the bacterium Capnocytophaga canimorsus)
  • The very young (less than 5 years of age) and elderly
  • Pregnant women

Some situations pose additional increased risk

  • Licking broken skin
  • Licking mucous membranes (e.g. mouth, nose, eyes)
  • Licking around invasive devices (e.g. people with an indwelling catheter)
  • Licking around the ears (especially in young kids)

What about the dog?

People aren’t the only ones who are exposed to bacteria when a dog licks them. Dogs can pick up bacteria from the person. We’ve previously shown that being allowed to lick people is a risk factor for hospital visitation dogs acquiring MRSA (methicillin-resistant Staphylococcus aureus).

What’s the take home message?

  • High risk people should not be licked by dogs.
  • Dogs that are sick, eat raw meat, or have risk factors for carrying resistant bacteria increase the risk.

The basic themes apply to more than licking, but to a variety of diseases and potential exposures.  High-risk people need to know they are high-risk, and they need to take some extra precautions; low-risk people need to think about the cost/benefit as well. If you’re low-risk and you like dogs licking you, go for it if you feel it’s worth the experience. If you don’t like it, why take the risk?

The risk dog slobber poses to the average person is quite low. Personally, I don’t like my dog licking me. That being said, if he catches me by surprise and licks me, I don’t run screaming from the room and douse myself with disinfectant.

“Kittens Can Cause Death” and Other Overblown Headlines

Posted in Cats

kitten-with-toyI’ve held off writing about this, but needed to get to it sooner or later. A recent article in the journal Emerging Infectious Diseases  (Nelson et al 2016) has spurred a serious of over-exaggerated and sometimes downright comical headlines. “Kittens can cause death; US study” is an Australian example of over-the-top reporting, probably by people who didn’t really read the manuscript.

The paper is a study of cat scratch disease (CSD), a bacterial infection caused by Bartonella henselae. Cats are the main reservoir for this bacterium, which is spread between cats by fleas. The bacterium can live in the cat’s bloodstream for prolonged periods of time without causing any problems for the cat.  As the name of the disease implies, cat scratches are a main route of exposure for people, but fleas play a role as well.  The fleas ingest the bacterium in the blood when feeding on the cat, and then pass it in their feces. People can be infected if a scratch gets contaminated with Bartonella-ladden flea feces, inoculating  the bacterium into the body. Cat bites might also play a role, as another way to inoculate a person with infected flea poop, or potentially even infected blood directly from the cat. Most often, inoculation of the bacterium probably doesn’t do anything – the body simply fights it off and produces antibodies against the bug. However, disease can obviously occur too depending on the circumstances.

This CDC study evaluated CSD in the US by looking at a health insurance claims database. The findings are different from some previous studies and perceptions, but not evidence of impending doom. Here are some highlights:

  • The average incidence of CSD was about 4.7 per 100,000 people.
  • There was a steady decrease in cases of CSD that did not result in admission to hospital (outpatient visits) over time, from a high of 5.7/100,000 in 2005 to 4.0/100,000 in 2013.
  • Not surprisingly, areas that tend to have lower flea populations had fewer CSD cases.
  • The highest incidence was in kids 5-9 years of age, at 9.4 /100,000. Overall, kids less than 14 years of age accounted for about a third of cases. (One thing to note is that the database did not have information on people over 65 years of age. They are another potentially increased risk group and one that would likely be at higher risk of being hospitalized from CSD).
  • Overall, most cases occurred in the southern US in the late summer and fall.

Much of what was reported in this study is consistent with what we already know. The distribution of disease across the US and the highest risk times of year are what would be expected for a flea-associated infection. The estimate of the incidence of disease is higher than some studies and lower than others. The incidence of hospitalization was a lot lower than other studies.

What does this study tell us, in the big picture? It’s a reminder that CSD is uncommon but still something that warrants attention, particularly as cat ownership increases. Bartonella henselae is a strange bug that is increasingly associated with problems other than CSD, so measures to reduce exposure (and ensure accurate diagnosis) are important.

Some take away messages:

  • Like many diseases, children are over-represented. This may be, in part, biological (being at greater risk of disease after exposure). However, a lot of it is probably due to an increased risk of kids being scratched or bitten by cats. Good supervision and education of kids about how to act around cats can reduce the risk.
  • This is one more reminder of the importance of flea control.

Controlling fleas and avoiding bites and scratches can make this a largely preventable disease.