Avian Flu

With approximately 2,000 registered attendees, members of the veterinary and human health communities, scientists, media, policymakers, general public and others showed their concerns about avian flu by tuning into the February 19 UC Health Grand Rounds. The one-hour, online session featured three experts from the UC Davis School of Veterinary Medicine and one from UC Davis Health.

Pasteurization is the only widely recognized method of killing H5N1, the virus that causes bird flu, in milk. However, pasteurization can be expensive and fewer than 50% of large dairy farms pasteurize waste milk.

Waste milk includes colostrum, the first milk after calving; milk from cows treated with antibiotics or other drugs; or any other factor that can make milk unsuitable and unsellable for human consumption. On farms, raw waste milk poses a potential risk of spreading avian flu, which so far has been confirmed in dairy cattle in 16 states.  

Last week, the first human death as a result of infection with highly pathogenic avian influenza (HPAI) H5N1, or bird flu was reported. According to the Louisiana state health agency, “The patient contracted H5N1 after exposure to a combination of a non-commercial backyard flock and wild birds.”

Every winter, millions of migratory birds fly south to warmer locales, passing over California Central Valley dairies and poultry farms. Many of these wild waterfowl are carrying the virus that causes avian influenza, based on the U.S. Department of Agriculture's wild-bird surveillance, says Maurice Pitesky, University of California Cooperative Extension poultry specialist in the School of Veterinary Medicine at UC Davis.

The sounds of barking elephant seals are again in the air along the breeding grounds of Península Valdés, Argentina—but it’s quieter. Roughly a year after a massive outbreak of H5N1 highly pathogenic avian influenza killed more than 17,000 elephant seals, including about 97% of their pups, scientists estimate that only about a third of the elephant seals normally expected here returned.

As highly pathogenic avian influenza (HPAI) continues to spread throughout the world, including on California dairy farms recently, experts on the subject from the UC Davis School of Veterinary Medicine have taken great strides to educate the public and industry partners on the subject.

Since 2022, a new, highly pathogenic strain of H5N1 influenza or “bird flu” has spread worldwide. In the U.S. it has affected over 100 million birds and for the first time, spread into dairy cows and a small, but growing, number of people. At UC Davis, experts in One Health — an approach that considers the health of people, animals and the environment together — are on high alert.

Dead silence met Marcela Uhart and her team when they arrived at the elephant seal colony at Punta Delgada, Patagonia on Oct. 10, 2023.

The discovery of fragments of avian flu virus in milk sold in U.S. stores, including in about 20% of samples in initial testing across the country, suggests that the H5N1 virus may be more widespread in dairy cattle than previously realized.

A poultry expert at the UC Davis School of Veterinary Medicine (SVM) has teamed up with a geographic information systems (GIS) expert at UC Agriculture and Natural Resources (ANR) and two wildlife health experts from the UC Davis SVM Wildlife Health Center (WHC) to create a map showing the spread of highly pathogenic avian influenza (HPAI) since 2021.