Worms & Germs Blog

Worms & Germs Blog

Promoting Safe Pet Ownership

A new Staph on the block

By Scott Weese on Posted in Dogs, Other diseases

It’s probably not actually a “new” bacterium but rather recognition of a species that we’ve been mixing up with something else, but regardless, a paper in the International Journal of Systematic and Evolutionary Microbiology (yes, that’s an actual journal) describes a new Staphylococcus species, Staphylococcus cornubiensis (Murray et al. 2018).

Here’s what we know:

  • The bacterium was isolated from a 64-year-old man with a soft tissue infection. Only a single bacterial colony was present on the wound culture. To me, that raises questions about whether it was clinically relevant or just a contaminant or part of the normal skin microbiota.
  • It’s a coagulase-positive staph. Staph can be coagulase-positive or coagulase-negative. Coagulase testing is a method that’s used to group staph, and the staph that cause the most disease (e.g. S. aureus, S. pseudintermedius) are coagulase-positive.
  • Genetically, it’s a member of the Staph. intermedius group (SIG). This includes S. pseudintermedius (the species that’s the main cause of staphylococcal disease in dogs), S. intermedius (mainly found in pigeons) and S. delphini (found mainly in dolphins and mink). It’s very closely related to these species but is different enough that it might be a different species.
  • It was also found during a study that went back and looked at historical SIG isolates from people.
  • It’s very closely related to a Staph isolated isolated from a dog in Norway in 2008.
  • Cornubiensis comes from the Latin name for Cornwall, the UK city where the infected person resided.

The close similarity to an isolate from a dog (and S. pseudintermedius) has led to a suggestion that it might have originated from a dog. Nothing is known about the patient’s dog ownership or dog contact, so it’s speculative. It’s not an unreasonable idea, but a lot more investigation needs to be done to support some of the headlines that have already sprouted as a result of this finding.

Most likely, this is a new Staph species that’s rare and of limited consequence to people or animals, and is simply one of the thousands of different bacteria that live in or on us, and our animals, all the time. I wouldn’t be surprised if it has a canine origin, but I doubt that this report means there are any new risks or new things to worry about.

Pets as a cause of death in natural disasters

By Scott Weese on Posted in Cats, Dogs

No, it’s not pets freaking out and killing people. It’s people staying in harm’s way during natural disasters because they can’t take their pets with them.

I saw some data about this from Hurricane Katrina years ago, and while I can’t remember the exact number, an astounding number of deaths were associated with people who didn’t evacuate because they couldn’t take their pets with them. It’s not just a natural disaster issue. Uncounted homeless people get sick and die each year because their pets can’t come with them to shelters, hospitals or doctor’s appointments, and there are few alternatives.

A recent CNN article again raises the issue of rescuing pets during natural disasters, with regard to the impending Hurricane Florence. One family that’s trying to ride out the storm in North Carolina cites the challenges of taking in their pets with them as a deciding factor.

It’s not a zoonotic disease issue, but pets and animal care are an often-overlooked issue in emergency preparedness and interventions with the homeless.

Bad headlines

By Scott Weese on Posted in Dogs, Other animals, Rabies

I realize headline writers are trying to attract attention, and sometimes they don’t know much about the content. As a result, some headlines are quite over the top, and that can freak people out. Here are some examples from the past couple of days:

4 year old girl catches life-threatening infection by trying on shoes while barefoot

In this case, the girl got an abrasion on her foot. Any break in the skin can lead to an infection, although infections aren’t common and serious ones are rare. Unfortunately, she got a serious one and developed sepsis, which is an infection coursing through her bloodstream.

Any minor wound can potentially lead to a serious problem, but it’s rare so context is important. Parent’s shouldn’t be afraid to have their kids try on shoes. That’s a pretty low risk activity.

Wellington County, Ontario swimmers might have been exposed to rabies: health unit

No, rabies virus hasn’t suddenly become a waterborne pathogen that is exposing swimmers to a fatal disease while swimming anywhere in the county. Rather, the health unit was informing people that might have encountered a sick bat that was pulled from a local lake that they might have been exposed.

Swimming… no risk.

Touching a sick bat that happened to be in the water… risk.

There’s a difference.

Canadian woman contracts rabies from bat bite while she was sleeping

Media reports do not uncommonly mess up “getting exposed to a rabid animal” and “getting rabies.” Usually, the issue is getting exposed to a rabid animal, as was the case with this person. It’s actually a success story from a public health standpoint (not so much from the bat’s perspective, though).

The quick version:

  • Woman wakes up when bat bites her arm.
  • She realizes rabies is a concern.
  • She catches the bat… (something that was easier in this case than my own household encounter with a rabid bat, since this one wasn’t flying much)
  • The bat is submitted for testing and is determined to have rabies.
  • The woman undergoes post-exposure prophylaxis.
  • Life goes on.

That’s a textbook response and it all started with some basic rabies awareness on the part of the person who was bitten. Without that, we might have been talking about a rare human rabies case in Canada in the next couple months.

Image: Big brown bats are one of the most common species of bats found in Ontario. (Photo credit: USFWS/Ann Froschauer)

Human rabies death, Delaware, US

By Scott Weese on Posted in Cats, Dogs, Other animals, Rabies, Vaccination

Animal Bat Fly Halloween Silhouette Bat BaHuman deaths from rabies are common in some developing countries (where tens of thousands die from canine rabies every year) but rare in developed countries. It’s an almost invariably fatal disease, but at the same time it’s almost completely preventable because of the quality of vaccines and post-exposure prophylaxis available. Getting those treatments to the people who need them is the big barrier.

In developed countries, it’s not an issue of vaccine access, but usually a lack of awareness of the need for it.

Recently, a woman in Delaware died of rabies.  This was only the 2nd rabies death in the state’s history, and the first since 1941. Little information has been released and there’s no indication of a likely source that I’ve seen. The woman owned a cat and it’s apparently being monitored, so there’s no chance that it could have been the source of infection given the timeline. Wildlife, such as bats and raccoons, are a more likely source. Bat bites are a concern in particular, since they are usually very minor and easy to dismiss (or miss altogether).

Whatever the case here, increased rabies awareness is still needed, even in North America. That includes the general public, physicians and veterinarians. More information about rabies can be found on the Worms & Germs Resources – Pets page, and in our archives.

Ticks know no borders

By Scott Weese on Posted in Cats, Dogs

While ticks don’t care about political boundaries, researchers often do (or practical aspects dictate that we must).  That doesn’t mean we can’t work together, though. A recent post at our related site petsandticks.com talks about the differences between US and Canadian tick submissions, and how US residents can submit ticks to the Show Us Your Ticks program south at Oklahoma State University.

More Capnocytophaga Q and A

By Scott Weese on Posted in Dogs

Capnocytophaga questions keep coming in. I guess that’s good in some ways, because I usually get a lot of blank stares when I mention that bacterium. A recent article about the risks of Capnocytophaga and exposure to dog saliva includes some good information about the topic, but the statements below highlight some issues:

It’s important to see a physician if you’ve been bitten by a dog, especially if it hasn’t been vaccinated against rabies.

Not really. Rabies vaccination has very little to do with the response to a bite. Yes, if the dog was vaccinated it reduces the risk that it had rabies, but since it’s not a guarantee, one of two things generally still needs to happen: either the dog needs to be tested (which requires euthanasia) or the dog needs to be observed to make sure it’s still clinically normal 10 days later (meaning it couldn’t have been shedding rabies virus at the time of the bite).  Regardless of the rabies risk, there is always some risk of infection from bacteria in the dog’s mouth.  Antibiotic treatmemt decisions are based on the location of the bite and the health status of the person. Seeing a physician after a bite is important, from an antibiotic standpoint, in:

  • People who are immunocompromised (including pregnant women)
  • Bites over the hands, feet, joints, face, bone, surgical implants or the genitals

Severity of the bite is only part of the decision. A very minor bite in a high risk person or a small puncture wound over a joint may pose much more risk than a big flesh wound in an otherwise healthy individual.

Those with weakened immune systems who have difficulty fighting off infections are at greater risk of becoming ill (such as those with cancer, diabetes or an HIV infection).

This may be true, but that’s not the main issue. These groups are at increased risk for various infections in gerenal, but evidence of a major risk from Capnocytophaga specifically is limited. The main risk group for this bacterium, by far, is people who have lost their spleen.

The best way to find out if your dog or cat carries this bacteria is to have a veterinarian run a test. That said, “a negative result may not mean the animal will always be negative, and the same is true for a positive result,”

No/yes. No, testing doesn’t make any sense. Most dogs are carriers and testing isn’t simple. So, a negative result may be a false negative. The correct part of the statement above is that even a true negative result may not mean the animal will always be negative.

When it comes to Capnocytophaga, a few things needto be highlighted:

  • Assume all dogs are carrying it in their mouths, so every bite or contact of saliva with broken skin or mucous membranes is a risk for exposure.
  • People who are at high risk for Capno infections (most notably splenectomized individuals) need to know that they need antibiotics after any bite or exposure of saliva to broken skin. The risk from Capno is very low in the rest of the population.
  • People at high risk for Capno also need to make sure their healthcare provider knows they’re at increased risk if they have signs consistent with Capno infection, especially after a known saliva exposure.
  • Healthcare workers need to know this bug exists.
  • Healthcare workers need to ask about animal contact routinely and pay particular attention to it when presented with a high risk patient.
  • Testing of dogs makes no sense. I’ll do it for free right now:
    “your dog is carrying Capnocytophaga.”
  • Treating dogs for this bug won’t help. Trying to eliminate a bacterium that has evolved to live in a dog’s mouth is probably futile.
  • A little common sense goes a long way. Knowing your risk status, improving dog training and handling to reduce bites, proper bite first aid and some basic awareness by healthcare providers are easy and probably highly effective preventive measures that are often overlooked.

More information about Capnocytophaga and about bites is available on the Worms & Germs Resources – Pets page.

Eastern Equine Encephalitis: Ontario

By Scott Weese on Posted in Horses

It’s that time of year. Mosquitoes have been annoying me for months (I get bitten multiple times a day where I live, even with repellent), but now they’re becoming a bigger issue. While mosquitoes bite all season, some of the diseases they transmit are only a significant risk at certain times of year.

One high profile disease that is spread by mosquitoes is Eastern Equine Encephalitis (EEE). As you can guess by the name, the virus that causes EEE  affects horses, in which it causes severe and usually rapidly fatal neurological disease. EEE can also affect people (and rarely other species, like dogs). It’s a relatively rare disease even in horses, but when it occurs it’s devastating, so the risk should not be taken lightly.

Recently, two cases of EEE were confirmed in horses on separate farms in Haldimand County, Ontario. Both were euthanized. Three more potential (but untested) cases were also reported in the area. The two confirmed cases occurred at the end of July/beginning of August, which is pretty early in the season for EEE in Ontario.  Whether that’s simply yearly variation cases or a sign that things are more active this year is hard to say, but time will tell.

For horses:

EEE is a rare but nasty disease, and there are vaccines available to help prevent it. The cost-benefit of vaccination against very rare diseases can be debated, but given the severity of EEE, horse owners in areas where the virus is found should consider vaccinating.  But remember that horses need to be vaccinated before the virus starts circulating in the area in late summer and fall (so don’t wait until you hear about a case in your area, or you may be too late to protect your horse in the same season).

For people:

Horses cannot transmit the virus to people (or other animals). We get the virus the same way horses do, from the bite of an infected mosquito.  Surveillance in horse lets us know about viral activity in the area (i.e. the horses can act like disease sentinels for people). Regardless, the risk of EEE, West Nile virus and other mosquito-borne pathogens means we should all take basic precautions to reduce mosquito exposure, such as the use of DEET repelants, avoiding high risk areas at dusk and dawn (e.g. swampy areas) and removing standing water where mosquitoes breed whenever possible.

Hopefully there’s not more to come in terms of EEE in Ontario, but considering we usually only see a handful of cases a year, this year’s early August numbers are a concern.

Doxycycline use and resistant Lyme disease

By Scott Weese on Posted in Dogs

“Use it and lose it” is often said when it comes to antibiotic resistance concerns. Every time we use an antibiotic (in a person or animal), there’s some potential for resistance to emerge. The more we use antibiotics, and the worse we use them, the greater the risk, generally speaking.

Questions about the (rampant) use of doxycycline for treatment of Lyme disease and the potential for development of resistance come up periodically. For me, it’s mainly in the context of (over)treatment of dogs that come up positive on screening tests but are clinically normal. However, the same concept applies to people.

So, what’s the risk?

From a Lyme disease standpoint, it’s not much of an issue. That may not make sense at first glance, but when you think about it, it actually does.

Let’s look at some scenarios:

  • If a dog is not actually actively infected with Borrelia burgdorferi, the bacterium that causes Lyme disease, antibiotic use can’t result in resistance in that particular bug since it’s not there (but there are still all the other bacteria in and on the dog’s body to consider too… see below).
  • If a dog is infected with the bacterium and it is treated with doxy, odds are pretty good the bacterium will die, so still no resistance.
  • For the B. burgdorferi in an infected dog to become resistant, it has to do it fairly quickly in the face of treatment. It’s most likely to occur from acquisition of a resistance gene from some other bacterium, given what we know about the mechanisms of doxycycline resistance in other bugs. So the B. burgdorferi needs to encounter another bacterium harbouring a doxy resistance gene. If B. burgdorferi caused infections in the gut, respiratory tract or on the skin, that would be more likely. However, in blood, within tissue and in joints, there’s much less of a chance of encountering another bacterium, let alone one that’s doxycycline resistant.

Okay, so in the very unlikely scenario of a resistant bug meeting B. burgdorferi, and a resistance gene being swapped, what now?

  • Well, not much from a population standpoint. It could make Lyme disease harder to treat in that dog, but since dogs are dead end hosts (they aren’t a relevant source of infection of ticks), resistant B. burgdorferi would stay in that dog.

None of this is meant to say “sure, doxy for everyone!” Unnecessary doxycycline use is still a concern, but it’s a concern because of development of resistance in the myriad other bacteria that are present in the body, not B. burgdorferi. Creation of a wide range of other doxycycline resistant bacteria is the concern (and it’s almost certainly happening).

Resistant Lyme disease shouldn’t be an issue. If it occurs, it’s going to happen by the bacterium picking up tetracycline resistance genes in the wild, and there’s not much reason for a bacterium to go to the effort of picking up and maintaining an extra gene if there’s no benefit (because there should be little chance of being exposed to those antibiotics in the wild). It’s possible it could happen, since there are lots of resistance genes out in circulation, and there may be artificial/human influences (e.g. antibiotic use in livestock, resulting in exposure of wildlife to resistant bacteria), and because bacteria naturally develop some resistance genes to fight amongst themselves. However, odds of this creating a sustained, significant population of resistant B. burgdorferi have to be low.

Capnocytophaga in the news… again

By Scott Weese on Posted in Dogs, Uncategorized

Every couple of months there’s a news report about a person with infection caused by the dog-associated bacterium Capnocytophaga canimorsus. Most of these reports don’t get too much attention, but every once in a while they get picked up pretty widely, resulting in another round of questions about this strange bacterium. It’s a bit of an oddball bug that can be found in the mouths of most healthy dogs. It doesn’t often cause disease in people, but when it does, it’s usually severe and is often fatal. One reason we don’t see much disease, despite the commonness of the bacterium, is that it tends to only sicken certain types of people, particularly those who don’t have a spleen.

While it’s a rare cause of illness, it happens more often than the news reports.  I hear about additional cases from people who have been infected themselves or have affected family members. Some common themes tend to come up, which can be frustrating because they’re issues we’ve been talking about for a while.

Here are a few of the comments that are commonly heard:

I’ve never heard of this bug before.

That’s not really surprising since it is a rare cause of disease, and not one most people would be expected to have heard about.

My doctor didn’t seem to know anything about it. Neither did my vet.

Again, not too surprising. It’s not something most MDs or veterinarians see regularly (or ever) in practice. Medicine and veterinary curricula are already packed, so rare things like this don’t get much, or any, attention. I’ve talked to physicians and most say they haven’t heard of it. I talk to veterinarians about Capno regularly as part of zoonotic disease talks, and only occasionally does someone know about it.

I’m missing my spleen and I didn’t know this was a concern.

That’s a problem. People who lose their spleen (or have a spleen that doesn’t work) have lost one of their immune organs. That makes them more susceptible to certain infections, such as this one. They need to know that, and what it means to them (e.g. if you are bitten by a dog, you need antibiotics, regardless of the location or severity of the bite).

No one at the hospital knew I was missing my spleen.

Unless (until, hopefully) we have a universal medical record system that takes your health info with you, things like this get missed. Someone who’s undergoing chemotherapy and is immunocompromised is highly aware of their immunocompromised status, and is motivated to tell their healthcare providers and it might be more obvious to the healthcare team. Someone who lost their spleen years ago may have no outward signs and may not think about it (especially if they haven’t been adequately informed about the risks). Sometimes (often, perhaps) that big risk factor isn’t identified in Capno cases until very late in disease, after it’s diagnosed. (e.g. Dr: “This is a disease that occurs most often in people that have lost their spleen.” Response: “Oh, he lost his spleen in a car accident years ago.”)

No one asked about animal contact.

This is a major area of concern and one on which we’re not making a ton of progress. I get involved with lots of cases of various types of infections each year where the simple “do you have animals?” or “have you had contact with animals?” question would have likely lead to a quicker diagnosis. Sometimes, like with Capno, quicker might be the difference between eventual recovery vs lifelong consequences vs death. It’s an easy question but it’s not asked often enough.

I didn’t think to mention the bite (or other exposure, such as a lick over broken skin).

This is another weak link. If no one asks, people need to know to offer the information and to make sure someone’s paying attention to it. Too often, no one mentions it because it was a minor bite, and that can sometimes mean the difference between life and death.

Fortunately, infections from this bacterium are rare. Unfortunately, when they occur they are usually very bad. They’re also highly preventable with some basic understanding of who’s at increased risk and what to do. Like a lot of things, a little communication goes a long way.

More information about Capnocytophaga is available on the Worms & Germs Resources – Pets page.