Worms & Germs Blog

Worms & Germs Blog

Promoting Safe Pet Ownership

Pet therapy dogs and MRSA

By Scott Weese on Posted in Dogs, MRSA/MRSP

My email and phone have been lighting up over the past few days about news reports describing a study presented at a recent scientific meeting in San Francisco. I wasn’t there and the results aren’t published, so I don’t have a lot to go on, but here are some highlights from the news article on Time.com:

The study was an assessment of the dynamics of transfer between people and visitation dogs in hospitals of a particular antibiotic resistant “superbug” called methicillin-resistant Staphylococcus aureus (MRSA).

  • Researchers looked at 45 kids who interacted with 4 visitation dogs – a relatively small sample size but an interesting study nonetheless.
  • About 10% of kids who didn’t have MRSA at first were carrying it after visits with the dogs. Whether that means they really became MRSA carriers or just had the bug transiently on their hands isn’t clear to me.
  • More time with dogs was associated with a greater risk of finding MRSA on the kids.
  • Kids were supposed to use hand sanitizers when interacting with dogs, but that wasn’t strictly enforced (so it probably wasn’t commonly done).

Is this surprising?

  • Yes and no.
  • We showed quite a few years ago that dogs that participate in hospital visitation programs are at increased risk of carrying MRSA, and that petting a dog that has been visiting people in hospital can transfer MRSA to someone’s hands (even when the dog’s not an MRSA carrier, i.e. the dog is simply mechanically transferring the bug from person to person on its body). This is a nice extension of that work, looking more at the dynamics of MRSA transfer.

Here are my take home messages:

  • Pet therapy programs have clear benefits, but they’re not zero risk (like most things in life). The cost-benefit needs to be considered in each case, but there are some basic precautions we can use to minimize the “cost” (risk) component.
  • MRSA is a human-associated bacterium, in the dog-human context. MRSA in dogs is typically acquired from people. Dogs can be a vehicle for MRSA transfer since they get touched frequently by multiple people. The more human contacts, the greater the chance that someone will deposit something on the dog’s haircoat.
  • Ultimately, it doesn’t matter if the dog is an MRSA carrier or if the person is an MRSA carrier, as long as basic hygiene practices are used. Most importantly, if the person washes their hands or uses a hand sanitizer before and after animal contact, the risk of transmission in both directions can be minimized.

The Society for Healthcare Epidemiology of America (SHEA) guidelines for programs involving animals in healthcare settings were published in Infection Control and Hospital Epidemiology in 2015.

Campylobacter outbreak from pet store puppies (and an antibiotic rant)

By Scott Weese on Posted in Dogs

This week’s edition of the CDC’s Morbidity and Mortality Weekly Report has a summary of the 2016-2018 campylobacterosis outbreak linked to pet store puppies. Nothing is particularly surprising, but that doesn’t mean it’s not disappointing (or depressing).

Click here for the complete article. Here’s a (relatively) brief summary:

  • It all started when sequencing of Campylobacter jejuni isolates identified the same Campylobacter strain from puppies from a commercial pet store chain in Florida and a person that bought a puppy from that chain in Ohio.
  • Over the course of the investigation, 118 illnesses in people were identified, including 29 pet store employees. This is presumably only a minority of the actual infections that occurred, since most infections over the course of an outbreak go undiagnosed.
  • Sick people were found in 18 states over slightly more than 2 years.
  • No one died, but 24% of confirmed cases were hospitalized.

A particular concern was that the Campylobacter isolates were resistant to all commonly used antibiotics. This obviously complicates treatment because it means that initial treatments would likely fail, prolonging the course (and potentially severity) of disease.

The antibiotic resistance aspect is particularly frustrating. Investigators in 4 states visited pet stores and collected antibiotic use information. They obtained records for 149 puppies, and 142 of those had received one or more courses of antibiotics before arrival or at the store.

That’s ridiculous.

What’s even more ridiculous is the fact that 55% of treated puppies received drugs when they were not sick – the drugs were being used for “prevention.” Another 38% received antibiotics for both prevention and treatment. Only 1% of treated puppies were treated solely because they were actually sick.

If you need that much antibiotic treatment to truly prevent disease, you’re doing something very wrong. If you’re using that much antibiotic without any idea whether it’s needed or not, you’re also doing something wrong.

To me, that indicates:

  • This approach to puppy breeding and selling is inappropriate on many levels.
  • Antibiotic use practices for pet stores need to be developed (and followed).
  • Veterinarians that dispense large volumes of drugs to pet stores need to be accountable for their use.

Hopefully this outbreak has been contained, but it’s far from certain. As the report says “Although the investigation is completed, the risk for multidrug-resistant Campylobacter transmission to employees and consumers continues.”

The article concludes with “Finally, antibiotics should only be administered under veterinary supervision with a valid veterinary-client-patient relationship, consistent with existing stewardship principles.” That’s very true, and while the majority of antibiotic use in companion animals is reasonable and the majority of vets care about antibiotic resistance and how they use antibiotics, there’s still a lot of room for improvement.

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.