Latest developments on avian flu virus in dairy cattle

Since the original diagnosis, herds in New Mexico, Ohio, Idaho, Michigan, North Carolina, Colorado, Iowa, Minnesota, South Dakota, and Wyoming have been identified as carrying HPAI.

By

Noah Rohlfing

Published on May 9, 2024

A few of the 300 cows at Salentine Homestead Dairy. — Photo:
Courtesy of Salentine Homestead Dairy

This story will be continually updated as new cases are reported to the Animal and Plant Health Inspection Service.

To date, 104 dairy herds in 12 states have been found to be carrying Highly-Pathological Avian Influenza (HPAI), a virus originally found in wild birds and usually associated with turkey and poultry flocks. The first known transmission found in a dairy cow herd was announced on March 25 by the U.S. Department of Agriculture (USDA), with herds in Kansas and Texas suffering from illness and testing positive.

Since the original diagnosis, herds in New Mexico, Ohio, Idaho, Michigan, North Carolina, Colorado, Iowa, Minnesota, South Dakota, and Wyoming have been identified as carrying HPAI. The USDA has created a webpage with a list of the date each herd was diagnosed. Since the most recent Animal and Plant Health Inspection Service (APHIS) update, two more cases have been reported in northwest Iowa.

Symptoms

Some dairy cows have tested positive for HPAI despite being asymptomatic, the USDA said on Wednesday. In a majority of cases, dairy cattle have shown symptoms such as these listed by the Kansas Department of Agriculture:

“Symptoms are mostly restricted to late-stage lactating cows and include a drop in milk production, loss of appetite, and changes in manure consistency. We encourage dairy producers to minimize wildlife access to their dairy cattle’s water and feed sources.”

While HPAI is normally fatal for poultry and turkey, dairy cows are generally able to recover in about two weeks when receiving treatment. A Reuters report confirmed that cows infected with bird flu have been culled or died in five of the 12 U.S. states with confirmed cases.

What the USDA is doing

In response to the growing number of cases and concerns, on April 24 Agriculture Secretary Tom Vilsack announced a mandatory testing ordinance that requires dairy cattle herds to be tested for HPAI before they can be moved across state lines. The order went into effect on April 29.

“This is an evolving situation,” said Vilsack during a teleconference. “Emergence of this virus poses a bit of a new risk.”

In addition, the USDA said in a press release that the Animal and Plant Health Inspection Service (APHIS) released 239 genetic sequences found in the recent H5N1 and HPAI influenza viruses found in dairy cattle and poultry for interested researchers.

“APHIS is urging dairy cattle producers and those who work in or with the industry to share epidemiological information from affected farms, even if they are not planning to move cattle interstate,” the release stated.

USDA emphasized the CDC’s assessment that humans are at low risk of contracting the disease. Three people in Texas and Michigan have tested positive for contracting H5N1 as of June 15.

While there are no documented cases of bird flu in beef cattle, the USDA announced April 29 the organization would test ground beef from the nine states with confirmed H5N1 cases.

What the FDA is doing

The FDA found particles of HPAI in samples of pasteurized milk as recently as April 23, but in a release said that it has full confidence in the safety of milk sold in grocery stores.

“Based on available information, pasteurization is likely to inactivate the virus, however the process is not expected to remove the presence of viral particles,” the FDA said in a report published by Reuters on Tuesday.

In addition, on April 25 Sid Miller, Texas agriculture commissioner, tried to assuage consumer fears about H5N1 in the commmercial milk supply.

“There is no reason for consumers to panic,” noted Commissioner Miller. “Milk and dairy products remain safe for consumption. Milk from affected cows is discarded before it can enter the supply chain. In the rare event that contaminated milk does enter the supply chain, pasteurization effectively kills viruses even if traces of the virus remain detectable.”