The ISU Veterinary Diagnostic Laboratory tests samples from animals for viruses such as avian influenza. (Photo courtesy of Veterinary Diagnostic Laboratory)
Avian flu was recently detected in cattle of two dairy herds in northwest Iowa, the state Department of Agriculture and Land Stewardship reported Friday, which increases the total number of affected herds to five.
The latest highly pathogenic avian influenza infections in cattle were discovered in a 3,000-cow herd in Plymouth County and a herd of 1,000 in Sioux, said Don McDowell, a spokesperson for the department.
The infections cause a significant drop in milk production, but cows typically recover within two weeks. The virus can be more devastating for poultry operations because it is very transmissible and lethal, and entire flocks are destroyed to prevent its spread.
That includes the 4.2 million chickens of an infected flock in Sioux County last month.
Federal agriculture officials have stressed the need to increase cleaning procedures and limit visitors to dairy farms and poultry operations.
In a Thursday report, the U.S. Department of Agriculture said most of the spread of the virus from Texas — where it was first identified in March — to other states was due to the transportation of infected cows. There is evidence that the first infections in Texas happened as early as December.
When the virus arrived in other states, it likely spread to more herds via people and equipment. The USDA noted that some infected herds in Michigan had not received any new cows within a month of their infections.
The USDA said it has likely been transmitted by veterinarians, workers who operate at multiple farms and workers who live with people who work at other farms. The department has not found evidence that wild birds are the sources of infection in states beyond Texas.
The other detections in Iowa dairy cattle were at two other herds in Sioux County and one in O’Brien County. McDowell said an investigation into the initial source of the infections is ongoing.
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