Dead Florida dolphin was infected with highly pathogenic bird flu

TAMPA, Fla. (WFLA) — A Florida bottlenose dolphin died from the "highly pathogenic" bird flu that has been sweeping the country, according to a new study.

Researchers at the University of Florida made the discovery following a necropsy on a dolphin that was found "in distress" in a Dixie County canal in March 2022. Despite rescue efforts, the dolphin died shortly after it was found.

Scientists did not suspect bird flu as the cause of death, however, a necropsy revealed the dolphin had contracted a highly deadly strain of the virus. The dolphin was found with brain inflammation and leptomeninges disease.

Upon further research, UF scientists found symptoms similar to those in other Florida wildlife that had been infected with the bird flu. Additional testing ruled out other potential agents at play in the dolphin's disease and confirmed the presence of bird flu in the dolphin's lung and brain.

Bird flu was first detected in North America in 2021, and has been spreading among birds and other mammals ever since, leading scientists to believe there was a possibility of "spillover" into other marine life such as dolphins.

Various tests detected the isolated virus in the bottlenose dolphin's brain tissue, but it's unclear how the dolphin might have contracted the flu.

"We still don’t know where the dolphin got the virus and more research needs to be done," Richard Webby, director of the World Health Organization Collaborating Center for Studies on the Ecology of Influenza in Animals and Birds at St. Jude Children's Research Hospital said.

Bird flu is widespread among wild birds in the U.S. and around the world, the Centers for Disease Control and Prevention reported. While the virus isn't very dangerous to humans, it's killed millions of birds and other wildlife.

The virus has also caused outbreaks in commercial and backyard poultry flocks.

"This investigation was an important step in understanding this virus and is a great example where happenstance joins with curiosity, having to answer the 'why' and then seeing how the multiple groups and expertise took this to a fantastic representation of collaborative excellence," Mike Walsh, D.V.M., an associate professor of aquatic animal health said.

The dolphin is the first cetacean ever recorded with the highly pathogenic avian influenza virus in the United States.