Cow-to-cow transmission can spread bird flu in dairy herds: USDA

WASHINGTON, D.C.: Last week, the U.S. Department of Agriculture (USDA) said that cow-to-cow transmission can spread bird flu in dairy herds, but how the virus is being moved around is still unknown.

Dairy herds in eight states and one Texas dairy worker have tested positive over the past month.

On April 19, Jim Lowe, associate dean at the University of Illinois College of Veterinary Medicine, said, "Those of us that have worked with influenza for a long time were fairly quickly saying, 'Yep it moves cow-to-cow'."

"You cannot explain the epidemiology any other way," he added.

The USDA said that while wild migratory birds are thought to be the virus' original source, its investigation into cow infections discovered "some cases where the virus spread was associated with cattle movements between herds."

It added that there is also evidence showing that the virus spreads from dairy cattle premises "back into nearby poultry premises through an unknown route."

Minimizing cattle movement and testing those intended for shipment, as well as improving safety and cleaning practices on farms, should avoid the need for further regulatory restrictions, the agency explained.

In May, officials reported that bird flu primarily affects older cows, but the USDA said additional data now indicate that younger cattle are also affected.