USDA: Bird flu sickens dairy cows in Kansas and Texas, but 'milk supply remains safe'

An illness affecting dairy cows in Texas and two other states over the past three weeks has been a mystery up until now.

The U.S. Department of Agriculture's Animal and Plant Health Inspection Service announced Monday that milk samples of sick cattle from two Kansas dairy farms and one in Texas tested positive for highly pathogenic avian influenza, more commonly known as bird flu.

Wild migratory birds are believed to be the source of the infection and the agency said viral testing and epidemiological work continues on herds in Texas, New Mexico and Kansas. While the ailment was at first chalked up to winter dysentery, veterinary officials initially had trouble pinning down the exact organism causing the disease.

Farmers and animal health officials became alarmed with cows in affected herds were hit with a sudden, acute drop in milk production with more severely impacted cows producing thick, concentrated milk – resembling colostrum – which cannot be sold.

Wild migratory birds are believed to be the source of the infection and the agency said viral testing and epidemiological work continues on herds in Texas, New Mexico and Kansas.

While it is uncommon for highly pathogenic avian influenza (HPAI) to affect dairy cows, the USDA said it has been tracking detections of the virus in mammals for many years in the United States to prepare for this eventuality.

The new development comes less than a week after Minnesota veterinary officials detected H5N1 avian flu in newborn goats at a farm where the virus had been detected in a backyard poultry flock. According to the Minnesota Board of Animal Health, this (at the time) was the first U.S. detection of HPAI in a domestic ruminant (cattle, sheep, goats, and their relatives).

Feds assure public milk supply remains safe

U.S. Sen. Roger Marshall, R-Kansas, told the Topeka Capitol-Journal that his office has been in close contact with federal and state officials and industry stakeholders.

"I want to relay that from the information we have received there is not a human health concern," he said. "Our dairymen work closely with veterinarians to monitor the health of their livestock and to ensure any sick cows are cared for and are not being milked for human consumption. All milk for sale at local grocery stores has also been pasteurized, which is effective against influenza.

How does HPAI affect cattle?

According to the Texas Animal Health Commission, the sick cows drop in feed consumption and simultaneously drop in rumen motility; the manure becomes abnormally tacky or loose and some cows experience fever. The impacted herds’ veterinarians have said that older cows in mid-lactation are more likely to be severely impacted than younger cows, fresh cows or heifers. Dry cows and heifers, so far, do not appear to be affected.

As secondary effects of the ailment, some cows have experienced pneumonia and clinical mastitis.

The Texas Animal Health Commission, USDA and Texas A&M Veterinary Diagnostic Lab are all working with practicing veterinarians and other partners to coordinate an efficient plan to monitor and evaluate affected dairy cattle, develop a case definition and conduct additional tests.

“A strong emphasis on enhanced biosecurity measures is encouraged,” the Texas officials said. “As monitoring and evaluation is underway, limiting people on and off premises and prioritizing diligent biosecurity practices is critical.”

They noted that any milk that appears to be abnormal should be diverted from the salable milk supply on the farm, as outlined in the Pasteurized Milk Ordinance.

No livestock displaying similar symptoms found in Wisconsin

Wisconsin veterinary officials said that they are not making any changes to import requirements for cattle from Texas in response to these cases. They did note that tuberculosis testing is required for cattle entering Wisconsin from Texas and Michigan. The agency encouraged producers to isolate any new additions to the herd for at least 7 to 10 days as part of a good biosecurity plan.

They noted that no animals “consistent with the current case definition” of the Texas cows have been reported in Wisconsin.

How officials pin-pointed the HPAI virus

The illness was first reported in late February and had affected 15 herds in the Texas panhandle area. Most veterinarians working on the problem had said they did not believe it was a novel disease – and that appears to have been confirmed this week. There were rumors blaming bioterrorism or a variant of avian influenza and the current information seems to have borne out the latter rumor. There are reports that some herds in New Mexico are also affected by the same problems.

The tests come as the USDA, the Food and Drug Administration and the Centers for Disease Control and Prevention have worked with state veterinary and public health officials to investigate sick dairy cows in Kansas, Texas and New Mexico.

"Initial testing by the National Veterinary Services Laboratories has not found changes to the virus that would make it more transmissible to humans, which would indicate that the current risk to the public remains low," the USDA news release said.

The veterinary experts are moving quickly to conduct additional testing for HPAI and will do viral genome sequencing to better understand what’s been going on with these dairy cows.

In the affected herds, the disease appears to impact about 10 percent of the animals. The American Association of Bovine Practitioners (AABP) held a conference call for members on March 22 and said that there are reports of some similar cases on Kansas dairies.

Dr. Fred Gingerich, a cattle vet who is executive director of American Association of Bovine Practitioners (AABP) told dairyherd.com that the disease appears to peak in about three to four days and lasts 10 days to two weeks. Older dairy cows appear to be more clinically affected and their lactation is more severely affected. “Although it’s not consistent with every herd, it appears that it’s mostly affecting animals that are in mid to late lactation. It’s pretty unusual that we have something going on in older animals and not in fresh cows.”

He told the publication that there doesn’t appear to be deaths caused by the disease, however, the milk production drop adds up to a huge economic loss on these dairy farms. Cows affected by the virus recovered from the initial illness without any secondary signs and are slowly coming back into production.

Federal officials said reporting the illnesses will help authorities monitor the situation and minimize the impact.

The state agency also encouraged producers to minimize wildlife access to water and feed sources for their cattle.