The Bird Flu Explained

April 26, 2024

The USDA and other regulatory bodies continue to provide public health updates on the highly pathogenic H5N1 avian influenza that has made headlines in recent months.

This week, federal regulators outlined efforts to control the spread of the virus, which has affected dairy cows in multiple states, while offering an assessment of the safety of the milk supply.

“The FDA and USDA have indicated that based on the information currently available, our commercial milk supply is safe because of these two reasons: 1. the pasteurization process and 2. the diversion or destruction of milk from sick cows,” the agencies said in a statement.

Here’s what you need to know:

• Background:  Public health officials have been monitoring a widespread outbreak of H5N1 bird flu in poultry and U.S. dairy cows, and one recent case in a U.S. dairy worker.
  • Idaho, Michigan, Texas, Kansas, South Dakota, Ohio, New Mexico, and North Carolina have reported outbreaks in cattle.
  • More than 90 million poultry have been affected since 2022.
• Threat level:  The CDC says the public health risk is low, but the agency is monitoring the situation to monitor people with animal exposures.
  • People should avoid unprotected exposures to sick or dead animals, animal carcasses, raw milk, feces (poop), litter, or materials contaminated by birds or other animals with confirmed or suspected HPAI A (H5N1)-virus infection, the CDC said.
• The milk supply:  The virus has been detected in raw milk, but the USDA is still researching samples to understand the ways pasteurization inactivates the virus.
  • On Thursday, the USDA said about 1 in 5 of retail samples tested positive for HPAI viral fragments, but “positive results do not necessarily represent actual virus that may be a risk to consumers.”
  • The USDA has unveiled mandatory testing for interstate movement of dairy cattle and mandatory reporting of results for laboratories and state veterinarians.
• Key safety measure:  Pasteurization and diversion or destruction of milk from sick cows are two important measures in the federal-state milk safety system, the FDA and USDA said.
• Quotable:  “To date, we have seen nothing that would change our assessment that the commercial milk supply is safe. Results from multiple studies will be made available in the next few days to weeks,” the FDA said.

Additional information about the highly pathogenic avian influenza outbreak is available online.