The Department of Agriculture announced on Monday that a highly fatal form of avian influenza, or bird flu, has been confirmed in U.S. cattle in Texas and Kansas. This is the first time cows infected with the virus have been identified.

The cows appear to have been infected by wild birds, with dead birds reported on some farms. The results were announced after multiple federal and state agencies began investigating reports of sick cows in Texas, Kansas, and New Mexico.

In some cases, the virus was detected in unpasteurized milk samples collected from sick cows. However, officials assured the public that pasteurization kills viruses, minimizing any risk to the milk supply.

Outside experts concurred that the infected milk was abnormal and posed little risk. Dairies are required to discard milk from sick animals.

The nation’s first detection of highly pathogenic bird flu in goats was announced in Minnesota last week. The flu samples from sick cows have not shown genetic mutations that increase the risk to humans, according to the agriculture agency.

Experts reassured the public that there was no need to panic. The spillover event was likely due to contact with diseased wild birds.

Dr. Jim Lowe, a veterinarian and influenza researcher, noted that cows were not expected to be highly susceptible to avian influenza. The cases highlighted a global bird flu outbreak that has impacted wild bird populations.

The outbreak, caused by the H5N1 bird flu virus, emerged in Europe in 2020. Wild birds can spread the virus to farmed poultry and other animals.

Although avian influenza viruses primarily spread among birds, the new H5N1 version has also infected mammals, raising concerns about potential evolution and the risk of a pandemic.

Dr. Bowman, an influenza expert, highlighted the need to quickly determine if the virus is spreading from cow to cow. Additional testing and analysis are ongoing.