COLUMNISTS

Animal Health Matters: Avian Influenza and the hunting season

Russ Daly
Special to the Farm Forum
Russ Daly

The duck hunters were out in full force that Saturday morning.

The roadside café in Webster seemed like a good breakfast stop on the way home after a raucous Friday spent with classmates at my high school reunion. The restaurant was filled with hunters rehashing stories on this morning of the duck opener. I was not intentionally eavesdropping, but the tables were close enough for me to hear tales of successes and challenges, duck species observed and the shot used in their shells.

One topic I didn’t hear was that of avian influenza – the bird flu. This wasn’t really a surprise. Had the restaurant been filled with turkey growers instead of duck hunters, I’m sure it would have come up.

That’s because, unfortunately, highly pathogenic avian influenza has reared up again this fall, as it did this spring. During that season, the disease has affected large commercial turkey farms as well as small backyard flocks, resulting in high death losses. By any account, it’s devastating to the affected producers. During the spring, almost 40 flocks totaling 1.7 million birds were infected with this virus.

It was much the same story back in the spring of 2015, with many flocks and millions of birds depopulated due to highly pathogenic avian influenza virus infections. But that year, problems were limited to the spring. As summer progressed, the number of new cases fell and the virus seemingly disappeared. In 2022, the story is unfortunately different. After a lull in cases this summer, newly infected bird populations have popped up this fall – some in locations that were also hit in the spring.

The source of highly pathogenic avian influenza virus this fall is the same as the source of the infections last spring – and how duck hunters intersect with the story. Wild migratory birds, especially waterfowl like ducks and geese, are the carriers of this virus. Virus fingerprinting tells us that the commercial flocks affected in South Dakota this spring were infected by virus strains carried by wild birds, not from farm-to-farm transmission.

While some sick or dying wild waterfowl have been documented, by and large these wild birds simply carry the highly pathogenic avian influenza virus from place to place without becoming sick themselves. How virus passes from waterfowl to domestic poultry, which are often housed in tightly closed barns, is not often clear. Since the virus remains alive in waterfowl droppings for a while, it could be blown or tracked into a barn. Direct contact between waterfowl and poultry might be possible in some cases, too.

The close association between the virus and waterfowl poses potential questions for hunters this fall. As of now, these concerns do not appear dire, but are worth considering nonetheless. After all, viruses, especially influenza viruses, are good at changing over time. What’s true about them now might not be in the future.

For one, waterfowl hunters should take steps to avoid carrying virus (which could come from handling normal-looking birds, or tracking through waterfowl habitats) to poultry they or their neighbors might have back home. Basic handwashing and proper management of boots and coveralls goes a long way.

Then there is the question of whether this avian virus could cause flu in people. Our department of health actually keeps tabs on this, contacting poultry workers who have been in contact with high concentrations of the virus to identify people who might become sick.

So far, these current bird strains seem to be adapted to birds only, with no crossovers to people in South Dakota yet. It’s important to monitor though: in the spring, a poultry worker in another state was identified sick from the avian virus (they fully recovered). Internationally, past highly pathogenic avian influenza strains have sickened and killed people.

While wild waterfowl were suspected to play a role in past poultry influenza outbreaks, that connection is much more solid with this year’s outbreaks. If you’re a hunter or someone spending time in the sloughs this fall, be aware that the avian influenza virus is likely present in the birds and their surroundings – and take steps to make sure you don’t track it somewhere it’s not wanted.

Russ Daly, DVM, is the Extension Veterinarian at South Dakota State University.  He can be reached via e-mail at russell.daly@sdstate.edu or at 605-688-5171.