As the unprecedented outbreak of H5N1 avian influenza continues in North America, there are various concerns about where this outbreak is going and the threats to other species….domestic and wild mammals, and people (us being just another ‘domestic animal’). My inbox is filled with questions about various concerns and scenarios. The one I’ll address today is about risks to vet clinics that treat backyard poultry.
Backyard poultry are increasingly common in many areas and, since they are outside and not managed with anywhere near the same degree of biosecurity as most commercial poultry, they are at high risk of exposure to avian flu if it’s circulating in wild birds in the area.
The good news
This H5N1 strain is not well adapted to infect humans (or mammals, in general). It lacks some of the genetic material that makes it able to effectively infect people. Only a couple human infections have been reported, including one in the US where the only symptom was fatigue. Transmission to other non-avian species is probably rare too, but all we can say is ‘probably’ because of limited testing of wildlife. Spillover has occurred, such as the recent cases in foxes in Ontario. Whether that’s a really rare event or a really rarely diagnosed event isn’t clear and is a big question. Still, it’s safe to say that, at this point, spillover risks are limited.
The concerning bits…
It’s still a flu virus and flu viruses change. The circulating strain can evolve and reassort (swap genes with other flu virus strains). We have other influenza viruses circulating in North America, including a human flu season that’s dragging on and influenza in other species such as pigs, horses and (in the US) dogs. There are also other avian flu strains around sporadically. The more flu viruses in circulation, the greater risk of them getting together to re-assort and make a new strain, potentially with more affinity for people.
So, back to the clinic situation.
Backyard poultry sometimes need vet care. Most often, that falls on small animal clinics, since poultry vets are limited (and may not treat backyard birds). Unlike most livestock, backyard poultry that need vet care are typically taken to the clinic (as opposed to livestock where vets visit the farm). This creates a few scenarios to consider for the vet clinic.
Transmission to people
- Fortunately, this seems to be very rare, at least at this point. Rare doesn’t mean it can’t happen, but the odds of bird-human infection (at least infection that causes noticeable disease) seems to be very low. So, it’s not likely someone handling an infected bird will get sick, but it’s possible.
- Another dynamic is worth considering, though. Hopefully the ‘stay home if you’re sick’ message is getting across but we know that’s not always the case, and people that are infected with influenza don’t always have symptoms. We might be getting into excessively theoretical issues here (I doubt it, though); however, we need to think about the potential impact of people that have human influenza getting exposed to birds that might have avian flu. If one infects the other (and therefore has an infection with two different flu viruses), that’s the recipe for re-assortment to create a new strain.
Overall, the risk is low. A comment I made today to someone was “There’s some degree of risk but in the absence of sick birds, the zoonotic risk isn’t likely any greater than that posed by your average new puppy (e.g. Campylobacter).” I think that’s a fair statement, but at the same time, one of my goals in life is not to become a case report describing a rare/new infectious disease, so I still want to take care.
Transmission to mammals
- The issues are similar to humans. The risk of transmission is low but not zero. I wouldn’t get too concerned about it, but I’d still rather not create the chance for rare bird-mammal transmission in the clinic, especially since we can largely prevent it with some basic practices (see below).
Transmission to other birds
- This is probably my main concern. That could be transmission to other backyard poultry (not too likely since there usually aren’t multiple backyard chickens at a clinic at the same time) or transmission to other pet birds. Susceptibility amongst different bird species varies but we’re seeing lots of wild birds dying from this virus. We don’t want to see it spread in a clinic to someone’s pet bird (or worse, to someone’s aviary). That creates risk of illness and death for the bird(s), and more human exposure to the virus.
So, what do we do?
- We do what we do every day….we assess and manage risk.
We can never 100% eliminate risk. That’s just not an option for most infectious diseases, especially flu. However, we can use some basic, common sense measures to reduce risk of avian flu transmission.
Since healthy looking birds can be infected, there’s no way to guarantee that a given bird isn’t shedding avian flu virus. However, we can identify situations where the risk is higher and increase the infection control measures that are used. These would include when..
- The bird is sick with signs that could be avian flu infection (including neurological disease)
- Other birds in the group are sick
- Other birds in the group have died
- Avian flu has been found in wildlife in the area
If we can keep poultry away from people and animals as much as possible, we greatly reduce the risk. That can be done a few ways..
- Admitting birds directly to isolation or another separate, contained space (vs hanging around in the waiting room)
- Examining birds outside so they never set foot in the clinic
- Housing hospitalized birds in isolation or a separate area
Minimizing the number of people that handle the birds in the clinic reduces transmission points. One or two people may be required for examination and procedures but that can be kept to a minimum.
Trying to make sure that poultry come into the clinic at a time when no other birds are present isn’t always possible if there’s a high bird caseload or for emergencies, but it’s something that can often be done.
PPE and hand hygiene
Some basic infection control practices can go a long way. We use routine practices on the assumption that any patient might be harbouring something infectious. Routine things like wearing proper protective outwear (basic lab coat) and hand hygiene will help. This can be increased if there’s specific concern (e.g. sick bird, dead birds in the group, lots of avian flu activity in the area) to include a disposable gown, mask and eye protection.
Rapid tests would be nice and are available for avian flu. However, we have not had success getting permission to import the tests for screening in places like clinics and wildlife rehab facilities. They’re not perfect and can never rule out flu. However, like with COVID-19 rapid tests, they could be a useful screen as a positive would indicate a need to user stricter precautions, get confirmatory testing done and provide more surveillance info. There was reluctance to use rapid tests for COVID initially, but they ended up being an easy and useful tool. Currently, the only testing we can get done is PCR testing through diagnostic labs, which doesn’t help us from a clinic control standpoint since the turnaround time is a few days.
The current H5N1 avian flu outbreak is definitely something to be concerned about. It’s having major impacts on domestic and wild birds. We want to control it to reduce the impact on those population and reduce the risk of this developing into something more. However, vet clinics should be able to treat poultry without much risk, if some basic measures are used.