Key warning signs about bird flu are all going in the wrong direction

This year has been marked by concerning developments in the virus’ spread, including widespread detections in wastewater and mutations observed in the virus.

Dec. 22, 2024, 12:00 PM EST / Updated Dec. 23, 2024, 1:45 PM EST
By Evan Bush

The Summary
• The bird flu outbreak took several concerning turns this year, with the number of human cases up to at least 65.
• Experts outlined several indicators that the virus’ spread is going in the wrong direction.
• Among them are recent detections of the virus in wastewater and signs of dangerous mutations.

The simmering threat of bird flu may be inching closer to boiling over.

This year has been marked by a series of concerning developments in the virus’ spread. Since April, at least 65 people have tested positive for the virus — the first U.S. cases other than a single infection in 2022. Dairy cow herds in 16 states have been infected this year. The Centers for Disease Control and Prevention confirmed the country’s first severe bird flu infection on Wednesday, a critically ill patient in Louisiana. And California Gov. Gavin Newsom declared a state of emergency last week in response to rampant outbreaks in cows and poultry.

“The traffic light is changing from green to amber,” said Dr. Peter Chin-Hong, a professor of medicine at the University of California, San Francisco, who studies infectious diseases. “So many signs are going in the wrong direction.”

No bird flu transmission between humans has been documented, and the CDC maintains that the immediate risk to public health is low. But scientists are increasingly worried, based on four key signals.

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