How Many U.S. States Are Affected by Bird Flu?

According to the Centers for Disease Control and Prevention (CDC), between March 25, 2024 and December 13, 2024, the H5N1 virus was detected in a total of 845 dairy herds across the United States - 630 of which were in California. Looking at the past 30 days, there have been new cases confirmed in just two states: one case in Nevada and 294 cases in California. All of these cases were on dairy milking cow premises. While the Golden State is the epicenter of the outbreak, the following map shows that since March 25, 2024 there have been 16 states in total with cases confirmed in dairy herds.

The current public health risk is considered low, with no cases of person-to-person transmission recorded. The CDC is watching the situation carefully and working with states to monitor people with animal exposures.