Human HPAI case reported after contact with Texas dairy cattle

A person in the United States has tested positive for highly pathogenic avian influenza (HPAI) A(H5N1) virus, as reported by Texas and confirmed by Centers for Disease Control and Prevention. This person had exposure to dairy cattle in Texas presumed to be infected with HPAI A(H5N1) viruses. 

The patient reported eye redness (consistent with conjunctivitis), as their only symptom, and is recovering. The patient was told to isolate and is being treated with an antiviral drug for flu. 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. However, 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. CDC has interim recommendations for prevention, monitoring, and public health investigations of HPAI A(H5N1) viruses.

CDC is working with state health departments to continue to monitor workers who may have been in contact with infected or potentially infected birds/animals and test those people who develop symptoms. CDC also has recommendations for clinicians on monitoring, testing, and antiviral treatment for patients with suspected or confirmed avian influenza A virus infections.

This is the second person reported to have tested positive for influenza A(H5N1) viruses in the United States. A previous human case occurred in 2022 in Colorado. Human infections with avian influenza A viruses, including A(H5N1) viruses, are uncommon but have occurred sporadically worldwide. CDC has been monitoring for illness among people exposed to H5 virus-infected birds since outbreaks were first detected in U.S. wild birds and poultry in late 2021. Human illnesses with H5N1 bird flu have ranged from mild (e.g., eye infection, upper respiratory symptoms) to severe illness (e.g., pneumonia) that have resulted in death in other countries.

H5 bird flu is widespread among wild birds in the U.S. and globally. These viruses also have caused outbreaks in commercial and backyard poultry flocks, and sporadic infections in mammals. HPAI in dairy cows was first reported in Texas and Kansas by the U.S. Department of Agriculture (USDA) on March 25, 2024. Unpasteurized milk from sick cattle collected from two dairy farms in Kansas and one in Texas, as well as a throat swab from a cow in another dairy in Texas, tested positive for HPAI A(H5) viruses of the genetic clade 2.3.4.4b, which is the same clade that is widespread among birds globally. On March 29, 2024, USDA’s National Veterinary Services Laboratories (NVSL) confirmed HPAI in a Michigan dairy herd that had recently received cows from Texas. HPAI has also been confirmed in a dairy herd in New Mexico, as well as 5 additional dairy herds in Texas. The most recent addition has been Ohio.

To reduce the risk of HPAI A(H5N1) virus infection, poultry farmers, livestock farmers and workers, veterinarians and veterinary staff, and responders should avoid unprotected direct physical contact or close exposure with sick or dead birds or other animals, carcasses, feces, milk, or litter from sick birds or other animals potentially infected or confirmed to be infected with HPAI A(H5N1) virus. Farmers, workers, and responders should wear recommended PPE such as an N95 filtering facepiece respirator, eye protection, and gloves, and perform thorough hand washing after contact. (e.g., see: PPE recommended for poultry workers) when in direct contact with sick or dead birds or other animals, carcasses, feces, or litter from potentially infected birds or other animals, and when going into any buildings with or that have had sick or dead birds or other animals, carcasses, feces, or litter from potentially infected birds or other animals. 

The USDA, CDC, FDA, and state of Texas reaffirmed that pasteurized milk and dairy products are safe to consume. Pasteurization is proven to inactivate bacteria and viruses, like influenza inclusive of avian influenza, in milk. FDA also recommends out of an abundance of caution that milk from cows in an affected herd not be used to produce raw milk cheeses.

Robust biosecurity protocols are critical to preventing and managing HPAI on dairy farms. The National Dairy FARM Program offers several valuable biosecurity resources providing dairy farmers with tools to keep their cattle and dairy businesses safe, including:

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