Bird flu may be spreading in cows via milking and herd transport

The bird flu virus spreading through dairy cattle in the United States may be expanding its reach via milking equipment, the people doing the milking, or both, U.S. Department of Agriculture (USDA) representatives reported today at an international, virtual meeting held to update the situation.

The avian virus may not be spreading directly from cows breathing on cows, as some researchers have speculated, according to USDA scientists who took part in the meeting, organized jointly by the World Organisation for Animal Health and the United Nations’s Food and Agricultural Organization. “We haven’t seen any true indication that the cows are actively shedding virus and exposing it directly to other animals,” said USDA’s Mark Lyons, who directs ruminant health for the agency and presented some of its data. The finding might also point to ways to protect humans. So far one worker at a dairy farm with infected cattle was found to have the virus, but no other human cases have been confirmed.

USDA researchers tested milk, nasal swabs, and blood from cows at affected dairies and only found clear signals of the virus in the milk. “Right now, we don’t have evidence that the virus is actively replicating within the body of the cow other than the udder,” Suelee Robbe Austerman of USDA’s National Veterinary Services Laboratory told the gathering.