California Governor Gavin Newsom declared a state of emergency on Wednesday as the H5N1 bird flu virus spread from the Central Valley into Southern California dairy herds. Meanwhile, federal health officials confirmed the first U.S. case of severe illness associated with the virus in a hospitalized patient in Louisiana. The developments have heightened concerns as the virus continues to spread nationwide through migratory birds.
The state of emergency will allow California agencies to coordinate more effectively, easing restrictions on staffing and contracting to respond to the outbreak.
“Building on California’s testing and monitoring system—the largest in the nation—we are committed to further protecting public health, supporting our agriculture industry, and ensuring Californians have access to accurate, up-to-date information,” said Newsom in a statement. He emphasized that the risk to the general public remains low but pledged to take all necessary measures to contain the virus.
Since August, 645 dairy herds in California have reported infections with the H5N1 virus. Nationwide, the number stands at 865 since the virus was first detected in Texas herds in March. The outbreak has also extended to pet cats in California, with three infections confirmed on Wednesday.
According to the Centers for Disease Control and Prevention (CDC), 61 human cases of H5N1 have been reported in the U.S. since March, with most involving mild symptoms such as conjunctivitis and respiratory irritation. In California, 34 cases have been linked to infected dairies. The only exception involved a child in Alameda County, whose infection source remains unidentified.
The Louisiana case marks the first severe illness attributed to H5N1 in the U.S. The patient had close contact with sick and dead birds from a backyard flock, officials said. This strain, identified as D1.1, has previously caused severe illness, including a Canadian teenager hospitalized in November. The virus circulating in dairy cows, known as B3.13, has resulted in only mild human symptoms to date.
The CDC is conducting a genetic analysis of the Louisiana patient’s virus to determine whether it has developed mutations that could increase its ability to infect humans or spread between people.
“These additional laboratory investigations help us identify concerning changes in the virus, including those that may signal an increased ability to infect humans or reduced effectiveness of treatments or vaccines,” said Demetre Daskalakis, director of the CDC’s National Center for Immunization and Respiratory Diseases, during a press briefing.
Research indicates that one viral isolate from a Texas dairy worker had mutations enabling airborne transmission between mammals, though it did not spread further. Experts remain cautious about the D1.1 strain, which carries a combination of mutations potentially supporting additional changes.
The H5N1 virus has been linked to high mortality rates in past outbreaks, with 948 cases and 464 deaths reported worldwide since its identification in 1997. However, most recent cases, particularly those involving the B3.13 strain, have been less severe.
The World Health Organization continues to monitor the virus’s evolution. Richard Webby, director of the WHO Collaborating Center for Influenza Studies, expressed concern about the D1.1 strain, noting its potential for unpredictable mutations.
JUST IN: Governor Gavin Newsom just issued a state of emergency in California in response to concerns over bird flu reports.
Newsom stated that he will “take all necessary steps to prevent the spread of this virus”
It’s COVID all over again. pic.twitter.com/iQSVaslvnB
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Daskalakis emphasized that the overall risk to the public remains low. The CDC is enhancing surveillance and testing capabilities to expedite the identification of cases, while California is leveraging its comprehensive monitoring system to contain the outbreak.
Newsom’s office highlighted the state’s commitment to addressing the crisis: “California has already established the largest testing and monitoring system in the nation to respond to the outbreak.”
Federal and state agencies continue to collaborate to mitigate the impact of the virus, with further updates expected as investigations and containment efforts progress.
