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Disease update: HPAI virus continues to evolve across the U.S.

by Wyoming Livestock Roundup

The U.S. Department of Agriculture (USDA), Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC), as well as state veterinary and public health officials are investigating an illness among dairy cows causing decreased lactation, low appetite and other symptoms.

Highly pathogenic avian influenza A (HPAI) H5N1 virus is an emerging disease in cattle, and federal and state agencies are moving quickly to conduct additional testing for HPAI H5N1 virus.

The agencies are conducting viral genome sequencing to better understand the situation, including characterization of the HPAI H5N1 virus strain or strains associated with these detections, as well as any other multi-factorial components of the disease event in dairy cattle.


On March 20, the Minnesota Board of Animal Health reported a juvenile goat residing on a Minnesota farm tested positive for HPAI, marking the first U.S. case of the virus in a domestic ruminant.

On March 25, the agencies confirmed the detection of HPAI in two dairy herds in Texas and Kansas exhibiting these symptoms.  

The USDA’s National Veterinary Services Laboratories (NVSL) also confirmed the presence of HPAI in a Michigan dairy herd which had recently received cows from Texas.

The NVSL reported the strain of the virus found in Michigan is very similar to the strain confirmed in Texas and Kansas, appearing to have been introduced by wild birds.

The Idaho State Department of Agriculture identified its first case of HPAI in a Cassia County, Idaho dairy cattle operation on March 28.

According to an April 1 press release from the USDA Animal and Plant Health Inspection Service (APHIS), the agency confirmed the detection of HPAI in a dairy herd in New Mexico, as well as five additional dairy herds in Texas.

Additionally, the CDC reported the same day, a person in Texas tested positive for HPAI H5N1 virus and announced this infection does not change the H5N1 bird flu human health risk assessment for the U.S. general public, which CDC considers to be low. 

CDC states, “People with close or prolonged unprotected exposures to infected birds or other animals including livestock or to environments contaminated by infected birds or other animals are at greater risk of infection.”

Texas Agriculture Commissioner Sid Miller confirmed on April 2, Cal-Maine Foods, Inc., a poultry facility in Farwell, Texas, received official notice of a positive test for H5N1.

Due to USDA guidance for poultry infections, the organization will be required to depopulate 1.6 million laying hens and 337,000 pullets at the West Texas facility.

The NVSL performed tests in Ohio, and on April 3, confirmed the virus in a dairy herd in Wood County, Ohio making it the sixth state to report cases.

The Ohio Department of Agriculture said the farm, located in the northwestern part of the state, had received cows from a Texas farm on March 8, where the virus was later confirmed.


APHIS reports this is a rapidly evolving situation and the USDA, federal and state agencies will continue to share additional updates as soon as information becomes available. 

“The goal of APHIS is to safeguard the health of the herd and protect the industry, keep our milk and beef supply safe and protect public health and human safety based on the most up-to-date information we have,” states the APHIS website.

Biosecurity recommendations from APHIS include heightening biosecurity practices to keep disease off of the farm.

They also recommend preventing and controlling the spread of the disease, paying particular attention to mammary health and good milking practices, such as equipment disinfection and milking sick cattle separately or last prior to parlor cleaning.

APHIS also recommends producers isolate newly added livestock to the premises and avoid housing multiple species of animals together.

They suggest limiting non-production animal access to farm areas and implementing measures to exclude domestic pets and wildlife from buildings.

Sick animals

According to recommendations by APHIS, do not move sick or exposed animals, and producers should monitor herds closely for cattle with clinical signs of the disease.

Symptoms include decreased milk production, reduced appetite, thickened and discolored milk, lethargy, fever and/or dehydration. 

“Milk samples from lactating cattle and nasal swabs from non-lactating cattle should be submitted to a National Animal Health Laboratory Network (NAHLN) laboratory for testing any suspect animals,” APHIS adds. “Although the HPAI H5N1 virus itself is a foreign animal disease (FAD), we are considering this as an emerging disease in cattle. “

APHIS encourages states and industry to use the established FAD/emerging disease investigation process to investigate credible reports of HPAI H5N1 virus in dairy cattle and beef cattle or other domestic livestock species.

“APHIS will reimburse for initial testing of suspect animals at NAHLN laboratories. Accredited veterinarians can collect samples and should work with state animal health officials and/or APHIS Veterinary Services’ area veterinarian in charge to obtain an FAD number,” the APHIS website reads.

At this time, APHIS is not recommending depopulation of cattle. In most cattle, this appears to be a self-limiting disease with resolution with palliative care, and currently, USDA is not be issuing federal quarantine orders nor is APHIS recommending any state regulatory quarantines or official hold orders on cattle.

To date, USDA has confirmed the detection of HPAI in seven dairy herds in Texas, two dairy herds in Kansas and in one dairy herd in Michigan, New Mexico, Idaho and Ohio.

Melissa Anderson is the editor of the Wyoming Livestock Roundup. Send comments on this article to

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