Highly pathogenic avian influenza confirmed in dairy cows

Detection of highly pathogenic avian influenza, HPAI, and subtype H5N1 in dairy cows was confirmed in March 2024 by the USDA USDA. This discovery was the first of its kind and shocked the global scientific community.

Official confirmations were made shortly after testing conducted at the Texas A&M Veterinary Medical Diagnostics Institute's Canyon and College Station Institute.

Following reports from local dairy practitioners and hundreds of tests excluding other potential pathogens, Canyon Lab tested nasal swab samples from dairy cows.

The positive results were the first indication that HPAI had surpassed species, and the cattle were not considered to be at a higher risk of infection with this particular virus strain, making it an unexpected finding.

Continuous efforts to answer questions

After a year of continuous monitoring and diagnostic services, TVMDL continues to protect animals, Human health Experts will proceed to finding answers to many questions related to non-via HPAI.

To date, 17 states have confirmed cases of avian influenza in cattle, with virus infections detected in at least 989 dairy herds.

Since its discovery in 2024, TVMDL has conducted over 12,000 avian influenza tests and continues to monitor this threat through cutting-edge diagnostic services.

“TVMDL runs these tests for animals, but they care about all the people who interact with them,” said Dr. Alexis Thompson of DACVPM, resident director of TVMDL Institute in Canyon.

According to the CDCPasteurization kills viruses in milk, so commercially available dairy products are safe for human consumption. However, certain HPAI virus strains are zoonotic diseases and can be transmitted from animals to humans. Individuals working directly with potentially infected animals may be at a higher risk of infection. To date, 70 cases of dairy and poultry workers have been infected Current outbreak.

“We do that for dairy workers, livestock owners, veterinarians, people who work in the wildlife sector and shelters,” Thompson said. “All of them are at a high risk of infection, so it's our duty to let people know where this virus is.”

Bird flu background

Bird flu Infectious viral disease caused by influenza type A virus infection Bird species. Infected birds can run the virus through mucus, saliva, or feces. Humans and animals can become infected with the virus by direct contact with infected animals and by contacting contaminated surfaces or airborne transmission.

The current outbreak of avian influenza began in early 2022 and has remained in birds for over two years. Most virus outbreaks tend to fade over time, but this outbreak is flooding around 30 mammal species across the US

Despite the virus being infected with different species over two years of driving, the Texas Panhandle's ripples to dairy cows have surprised experts.

“We know that birds have been hosting avian flu for decades,” Thompson said. “We were shocked by the positive tests of cows because they are known to get flu type D, but not flu type A.”

Discovery of HPAI in dairy cows

In late February 2024, TVMDL began receiving notifications for sick cows with reduced milk production and fever, among various clinical signs, at dairy farms in the Texas Panhandle. Working with dairy practitioners, TVMDL put together a set of testing options to determine the cause of the illness.

“In response to all this, our lab has begun testing a large number of samples to rule out any possible pathogenesis,” Thompson said. “We ruled out many common diseases in dairy cows, which helped veterinarians and other labs working on this unusual event narrow down the possible causes.”

While ongoing negative test results were insightful, the diagnostic laboratory did not have any specific suspected diseases to investigate.

The incident finally broke after reports of unexplained morbidity in several wild birds and cats from the same dairy farm.

Connect cat and bird hosts to dairy cows

TVMDL received the first report of the bird that passed away on March 15, 2024, and three days later cat specimens began to arrive.

Kiril Dimitrov, DVM, Ph.D., assistant agency director for TVMDL Assistant Microbiology Research, oversees avian influenza testing at both the Canyon and College Station Lab locations.

“The positive outcome of cat bird flu was not surprising,” Dimitrov said. “For over 25 years, we knew that cats are susceptible to the virus. What was surprising was the big numbers.”

Dairy veterinarians shared their findings at the Diagnostics Laboratory, including one dairy product lost 20 cats in 24 hours. Based on this information, the veterinarian began submitting samples from the cat for testing. Tests revealed that the cat was not only positive for HPAI, but also carried a significant amount of viral load.

Thompson questioned the possible connections between dead birds, cats and sick cows and threw the avian flu into a list of potential pathogens.

Multiple samples of cats tested positive for HPAI from March 19th to 22nd, 2024. On March 22, 2024, TVMDL tested nasal swab samples from sick cows who live in the same dairy products as cats infected with avian flu. Surprisingly, SWAB was positive for HPAI subtype H5N1.

“The current hypothesis is that the disease jumped from birds to cows and from cows to cats,” Thompson said. “There's always a worry whenever virus jumps from one species to another, as each new host has a smaller bridge.”

What happens when a pathogen jumps a species?

Initially, Thompson was a dairy farmer. Poultry industry For highly pathogenic birds influenza It was first discovered – particularly the massive depopulation of affected surgeries and dairy degradation. 3 million Americans.

“I was thinking about the future and how this pathogen would affect this large community,” Thompson said. “It's a pathogen that jumps into new species. There were a lot of unknowns back then, but we still do.”

In the week of March 25, 2024, when USDA announced confirmation of HPAI type H5N1 in dairy cows, TVMDL tested 138 samples from 12 Texas, New Mexico and Kansas Dairy Farm. HPAI positive samples were detected in all farm dairy cows with submitted samples.

Now, one year after the national testing, experts are increasing their knowledge of outbreaks. For example, despite concerns about disease-related clinical signs, affected groups tend to have lower mortality.

Protects the dairy industry from bird flu

Since HPAI's first discovery Dairy cowTVMDL and other diagnostic lab testing paves the way for the establishment of multiple federal orders and programs aimed at protecting the dairy industry.

• In April 2024, the USDA issued a federal order to ensure that all breastfeeding cows are tested for HPAI before being transported across state boundaries, hoping to limit spreading of infectious diseases.
• In late May 2024, USDA launched it Dairy Group Status Programa voluntary program for dairy producers to monitor herd health and promote transport efficiency.
• In December, USDA announced it National Breast Examination Strategya federal order calling for testing of raw milk at the state level to strive for freedom from illness.

As a member of USDA's National Animal Health Laboratory Network, TVMDL offers federal orders and routine surveillance tests for related dairy farms.