Two dairy workers in California have been infected with bird flu, marking the 15th and 16th human cases detected in the U.S. this year. The cases were confirmed in workers who had been in contact with infected cattle in California’s Central Valley, where over 50 herds have been affected since August. The workers exhibited symptoms like eye redness, known as conjunctivitis, and experienced mild symptoms.
Health officials in California stated that the infected workers were employed on different farms, with no known link between the cases. This suggests that the transmission likely occurred through animal contact rather than human-to-human transmission. The U.S. Centers for Disease Control and Prevention (CDC) validated the positive test results, marking the first cases in California. CDC officials mentioned that new cases of bird flu in individuals exposed to infected animals are not unexpected, although the risk to the public remains low.
Across the U.S., more than 250 dairy herds in 14 states have been infected since the confirmation of the H5N1 avian influenza outbreak in March. While avian influenza has been spreading among wild and domestic birds for several years, it was recently detected in dairy cows. Prior to this year, there was only one reported case of bird flu in a person, a poultry worker from Colorado who fell ill in 2022. Most cases this year have been linked to workers who had contact with cattle or poultry in states like Colorado, Michigan, and Texas. There was also a case in Missouri where the infected person had no known animal contact, and the source of the illness remains undetermined.