Bird flu poses unanswered questions in leap to dairy cows

Bird flu now has struck three dairy cow herds in Iowa, ag officials announce

By Caleb McCullough,

Gazette-Lee Des Moines Bureau

DES MOINES — The U.S. Department of Agriculture has sent a “strike team” to Iowa to assist it with testing after the highly contagious bird flu usually associated with poultry flocks now has been discovered in three dairy cow herds in the state.

The presence of the virus in dairy cows presents a new challenge and a number of unanswered questions, experts said. The virus primarily affects birds, but has been observed in mammals for years and made the jump to dairy cows in the United States for the first time in March.

It was detected last week in two northwest Iowa herds, and Wednesday in yet another northwest Iowa dairy herd.

Three human cases of the virus have been identified this year in the country — none in Iowa — but officials have said the threat to the public is low, and human-to-human transmission has not been recorded.

Iowa Secretary of Agriculture Mike Naig encouraged farmers to take precautions.

“This is going to take the entire agricultural community working together because we all have a stake in protecting the herds and flocks of Iowa,” he said in a statement.

HOW ARE DAIRY HERDS BEING TESTED?

Iowa officials long have had a practice of testing poultry flocks when a case of avian flu in one of the birds is detected. Now, they are expanding that practice to dairy farms.

Officials identified the first case of bird flu in dairy cattle June 5 in O’Brien County. The second case was reported June 7 in Sioux County. A third case was reported Wednesday, also in a Sioux County herd.

The Iowa Department of Agriculture and Land Stewardship will begin testing dairy farms within 20 kilometers — or over 12 miles — of any poultry farm where the virus is detected, said department spokesperson Don McDowell.

“This existing testing protocol, long in place for poultry, is expanding to now include dairy,” Mc-Dowell said. “Of course, we always encourage dairies anywhere within Iowa to reach out to the department if they have cattle expressing clinical signs” of bird flu.

HOW IS THE VIRUS INFECTING CATTLE?

Federal and state officials are studying the infected herds across the country to determine how the cows may have contracted the virus.

In a statement, Mc-Dowell said wild birds are frequent carriers of the virus.

“We need to learn more about how the virus is introduced to new flocks/herds and how it is spreading,” he said. “We are always looking for epidemiological clues and ties and that’s why we are making our requests of USDA to assist with research.”

The USDA has deployed a strike team to the state to investigate the source of the infection, a USDA spokesperson said. The USDA also has created tools to fund protective gear, biosecurity efforts and vet costs for affected herds, and a program for farmers to test their milk for the virus.

The disease also appears to be spreading between cows, rather than just from birds to cows, making interstate transportation a likely culprit for the spread, said Iowa State University Dairy Extension Veterinarian Phillip Jardon.

Since late April, the USDA has been requiring cattle transported across state lines to receive a negative test for the virus. The Iowa ag department currently is not restricting movement of dairy cows within the state.

WHAT STEPS SHOULD FARMERS TAKE TO PREVENT SPREAD?

The disease is much more devastating for poultry farmers than for dairy farmers, Jardon said.

Over 4 million chickens were euthanized at a commercial facility in Sioux County when the bird flu was detected in May, the first case this year in Iowa. More than 103,000 turkeys were destroyed at a Cherokee County facility in early June.

When a flock is identified with the virus, the entire flock is culled to prevent further spread. However, cows generally recover from the virus over time.

“Dairy farmers need to keep that in mind, that it’s important for them to be cognizant of this and appreciative of our colleagues on the poultry side,” Jardon said. “We should control it in the dairies partly because of our poultry farmer neighbors.”

Jardon said dairy farmers should step up control of pests, including birds and small mammals like rats and mice. Farmers should also limit unnecessary travel of people on the farm and between farms.

After an infected herd is detected, the state ag department works with the farm to discuss biosecurity practices and containment strategies, McDowell said. The department works with state and local public health departments to monitor human health, and conducts investigations to determine how the virus was introduced.

The USDA plans to make funding available from an existing emergency assistance fund to help farmers who lose milk production because of the bird flu, the spokesperson said. The reimbursement will likely be 90 percent of market value.

The USDA already has a process to compensate farmers for birds that are slaughtered because of the virus, but the state ag department asked for those formulas to be updated to increase compensation.

IS THERE A RISK TO HUMANS?

Three human cases of the virus in the United States have been identified this year, all in dairy farmworkers. The documented human cases this year have been mild.

But the quick adaptations of flu viruses make it something to watch, Jardon said.

“Influenza viruses mutate fairly readily. That’s one reason the flu is such a problem in humans,” Jardon said. “ ... And it seems to want to jump species. We shouldn’t be too alarmed, but we should be monitoring the situation carefully.”

The Iowa Department of Agriculture said animal products, including poultry, eggs and pasteurized milk and dairy products, remain safe to eat and drink.

Jardon said the pasteurization process easily kills the bird flu virus.

Federal officials have encouraged states that allow the sale of raw milk — like Iowa — to implement measures to stop it from being sold. Iowa lawmakers allowed the sale of the milk last year, which does not go through the pasteurization process.

HOW WILL BIRD FLU AFFECT STATE FAIR?

The Iowa Department of Agriculture said last week it is considering additional requirements for livestock exhibitions at the Iowa State Fair, which begins Aug. 8.

In 2022, the ag department canceled live bird shows for a period because of bird flu.

“Agriculture and showcasing livestock are cornerstones of the Iowa State Fair experience,” Iowa State Fair Chief Executive Officer Jeremy Parsons said in a statement. “As with all matters related to animal health, we are monitoring the situation and maintaining regular contact with the Iowa Department of Agriculture.”