H5N1 Bird Flu Outbreaks in U.S. Dairy Cows and Poultry

Several black and white dairy cows standing in a barn eating hay.

Currently, H5N1 bird flu is widespread in wild birds worldwide and is causing outbreaks in U.S. dairy cows and poultry with three human cases in U.S. dairy workers in spring 2024 and a previous case in 2022. H5N1 bird flu is a disease caused by certain flu viruses that usually spread between birds. Infected birds can spread the virus through their mucus, saliva or feces. People rarely get bird flu, but when they do, it is often through unprotected contact with infected birds.

Retail Milk Supply

On April 25, the U.S. Food and Drug Administration reported that its nationwide survey of retail milk has found remnants of H5N1 avian flu viruses (bird flu) in one in five samples, with the highest concentrations in regions where outbreaks in dairy cattle have been reported. The FDA reiterated that they have not changed its assessment that the nation's milk supply remains safe. So far, early work on milk samples that were positive for H5N1 fragments have not found any potentially infectious virus. Bird flu has been detected in dairy cows in several states, including Kansas.

Consuming Raw Milk

Based on current knowledge, it's uncertain whether H5N1 viruses can be transmitted through consuming unpasteurized (raw) milk from infected cows. However, raw milk can carry harmful microorganisms that can seriously endanger consumers' health. It is recommended to refrain from consuming raw milk amidst the H5N1 outbreak due to the heightened risk of exposure to the virus, which could lead to illness.

Public Health Risk

While the current public health risk is low, CDC is watching the situation carefully and working with states to monitor people with animal exposures. CDC is using its flu surveillance systems to monitor for H5N1 activity in people.

For more information:

Health and Environment