The H5N1 bird flu has been rapidly spreading through dairy farms in California, the largest milk producer in the country. The number of confirmed infected cow herds has doubled over the weekend, from 17 on Thursday to 34 on Monday morning. California now ranks second among affected states, with 232 herds in 14 states being infected with the bird flu.
California officials had targeted the herds for testing due to elevated risks from their recent connections with the initial affected premises. They stated that the positive results were expected and fit with the state’s plans of early detection. This allows them to work with farms quickly to implement enhanced biosecurity measures, cow care, and employee protection.
Despite the state’s preparations and readiness, public health experts are concerned about a puzzling case of H5 bird flu in a person in Missouri. This case is the 14th human infection amid the dairy cow outbreak this year, with all prior infections being in farmworkers exposed to infected animals. The Missouri case had no known exposure to animals, raising questions about how the infection occurred.
While the Missouri case has recovered, health officials are conducting further testing to understand the transmission of the virus. Another person in the household with the Missouri case fell ill at the same time, suggesting a possible common exposure to the virus. The CDC is now conducting serological testing to see if the household member has developed antibodies against the bird flu.
There is no evidence of human-to-human transmission yet, but health experts are concerned about the lack of testing and the potential for unseen transmission. As the influenza virus spreads to new mammalian species, there are concerns about its ability to adapt to humans and cause more severe disease. Influenza experts have long been worried about the virus’s pandemic potential and are closely monitoring the situation.
