The highly pathogenic avian influenza (HPAI) H5N2 virus has struck two more turkey farms in central Minnesota, the sixth and seventh ones in the state to be hit in a little more than a month, federal and state officials announced today.
One outbreak occurred in Stearns County—which already had two previous outbreaks—at a farm that lies within the control area that was set up around one of the earlier ones, the US Department of Agriculture (USDA) said in a statement. The second outbreak is in Kandiyohi County, which borders Stearns on the southwest.
The Stearns County incident involves a farm housing 76,000 turkeys, the USDA said. Only one of three barns on the farm was affected, said Bethany Hahn, a spokeswoman for the Minnesota Board of Animal Health (MBAH), but plans call for destroying all the turkeys to check the virus's spread.
In Kandiyohi County, the virus hit a farm holding 26,000 turkeys, the USDA said. Just one of four barns on the farm was affected, Hahn reported, but plans call for culling all the turkeys there as well. The USDA described the turkeys as a "molting breeder replacement" flock.
In both cases, increased deaths in the flocks prompted testing by the University of Minnesota Diagnostic Laboratory in St. Paul, and the findings were confirmed by the National Veterinary Services Laboratories operated by the USDA's Animal and Plant Health Inspection Service (APHIS) in Ames, Iowa.
Midwest first affected Mar 5
The first Minnesota H5N2 outbreak was reported in Pope County on Mar 5, marking the virus's first appearance in the Midwest after several detections in Washington, Oregon, and Idaho earlier in the winter. Since then, the virus has hit turkey farms in Lac Qui Parle, Nobles, and Stearns counties.
Last month also brought H5N2 outbreaks on two Missouri turkey farms and one in Arkansas, plus a backyard poultry flock in Kansas. Also, the USDA reported an outbreak on a South Dakota turkey farm Apr 2.
Officials have not reported any connections between the seven Minnesota outbreaks, and none of the outbreak sites have been identified. The MBAH has established control areas about 6 miles in diameter around each affected farm, and in Stearns County a large portion of the three circles overlap, creating one larger control area, according to the board. It said about 25 commercials farms and 80 backyard poultry flocks have been identified within the area.
Hahn said there was no new information today in the investigations into how the virus reached the turkeys on any of the farms.
All of the Minnesota outbreaks involved farms where all turkeys were kept inside barns full-time, according to Hahn. And in all but one of the outbreaks, the virus was detected in just one of several barns on the farm, she said. The exception was the outbreak in Lac Qui Parle County, where two of three barns had sick or dead turkeys.
In the seven Minnesota outbreaks, about a third of the 343,000 turkeys on affected farms died of H5N2 infection, and the rest were euthanized, according to the MBAH.
Testing planned in wild birds
Wild birds can carry the H5N2 virus without looking sick, the USDA says. No signs of H5N2 were found in testing of wild birds near the site of the first outbreak, in western Minnesota's Pope County. The state Department of Natural Resources (DNR) is planning to test wild birds near the sites in Stearns, Kandiyohi, Nobles, and Lac Qui Parle counties this week and next, Michelle Carstensen, PhD, the DNR's Wildlife Health Program supervisor, told CIDRAP News today.
She said the DNR will collect fecal samples for testing, using bait where needed to gain access to fresh samples. "We hope to get our first batch of samples in by the end of this week, so we'd get some test results next week," she added.
No human cases of the HPAI H5N2 strain have been reported. The Minnesota Department of Health is working with poultry workers on the affected farms to make sure they are taking proper precautions, the USDA said.
Apr 6 APHIS statement on Stearns County outbreak
Apr 6 APHIS statement on Kandiyohi County outbreak
MBAH updates on Minnesota H5N2 outbreaks
Apr 6 MBAH summary of outbreaks