After a year-long lull, highly pathogenic avian influenza is back in Wisconsin.
The state Department of Agriculture, Trade and Consumer Protection first confirmed the return of the virus in a small backyard flock in Taylor County on Nov. 17.
The DATCP has since confirmed five more cases on commercial farms spreading across Barron and Trempealeau County.
Wisconsin’s state veterinarian Dr. Darlene Konkle says it’s not surprising to see an uptick in cases during the fall season. She says the fall migration of birds, especially waterfowl like ducks and geese, is attributed to the rise in cases.
“Migrating waterfowl, as they move back from areas in the Arctic that are their breeding grounds and back through North America on their way south, they stopped to rest and to eat in these various areas around wetlands, and that's when we start to see more cases,” Konkle says.
The H5N1 bird flu strain that’s been circulating throughout the U.S. since late 2021 makes this virus highly pathogenic, or contagious, Konkle says.
“This one is a high-path virus that came over to North America from Europe and it’s different from other viruses we've had in the past,” she says. “This virus seems to have some staying power for whatever reason. It's got the capability to remain in the environment a little longer and continue affecting birds.”
Konkle says a similar bird flu outbreak took place between 2014 and 2015 due to a different virus strain, H5N2. During the outbreak, more than 50 million chickens and turkeys across the U.S. died of the virus or were killed off to stop the spread of the virus, according to the U.S. Department of Agriculture.
Unlike the 2015 outbreak, Konkle says animal health officials are noticing that the virus is not being spread from farm to farm.
“In the vast majority of cases in this current outbreak, each one of these detections that we're seeing across the country has been mostly an individual introduction from some kind of contact with the virus in the environment,” she says.
Some of the symptoms for this strain of bird flu include advanced respiratory signs like sneezing and snicking, lethargy, decrease in egg production, low feed and water intake. Konkle says it’s most often domestic birds, like chickens, that are infected by the virus experience sudden death.
“We're asking our poultry owners to be really vigilant and look closely at their flocks to see any signs to detect those early and to report those to [DATCP] as soon as they notice something unusual, or report them to their veterinarian,” she says.
As soon as a positive case is detected by Wisconsin’s Veterinary Diagnostic Laboratory, DATCP agriculture officials are notified and work with farm owners to quarantine their flocks.
“We do work with the farm owner to depopulate any remaining birds as humanely and as quickly as possible,” Konkle says. “We also work with the farmer and with our [U.S. Department of Agriculture] counterparts to dispose of those birds in a way that eliminates the virus and also prevents any further spread.”
More than 300,000 birds in Wisconsin have died of the virus or have been killed off to stop the spread of the virus since the first reported case on Nov. 17. The first case in Taylor County has been the only backyard flock affected so far, the other five cases were detected on commercial poultry farms.
Once DATCP has eliminated the virus off a farm, they set up a control and surveillance area around the affected farm to make sure other nearby flocks weren’t infected.
Konkle says it’s difficult to know how long the H5N1 virus will continue to impact birds throughout Wisconsin and the rest of the world, but suspects it’ll be a while.
“The virus itself can survive just fine in our winters,” she says. “Influenza viruses don't mind cold, wet conditions, which is basically winter in Wisconsin, so we could potentially see more cases over the winter. We tend to see the largest rises [in cases] correspond to the migration season, so I would expect cases to drop off more in the dead of winter. But we still really want to remain vigilant because we certainly could get cases popping up really, at any time of the year.”
Konkle says the best thing small, backyard flock owners and large, commercial flock owners can do to help mitigate the spread of bird flu is to practice good biosecurity:
- Washing your hands before and after handling poultry
- Using equipment and clothing dedicated to working with poultry
- Depending on the size of flock, showering before and after working with poultry
- Isolating and monitoring new birds before introducing them to the rest of the flock
- Ensuring birds are kept separated from other birds, especially wild birds and areas where wild birds congregate such as ponds and other waterways
_
