The Florida dolphin, a young male, was found in March in a canal in Dixie County, where area residents noticed that the animal had become trapped between the pilings of a pier and a sea wall, said Dr. Michael Walsh, a veterinarian at the University of Florida College of Veterinary Medicine who leads the university’s marine animal rescue program.
By the time rescuers arrived, the dolphin had died, he said. The team, which routinely conducts necropsies, collected a variety of samples from the dolphin and stored them until they could be analyzed in more detail.
At the time, the scientists had no reason to suspect that bird flu had made its way into dolphins, and they were not in a particular rush, said Dr. Walsh, who collaborated on the investigation with Dr. Robert Ossiboff, a veterinary pathologist, and Andrew Allison, a veterinary virologist, both at the University of Florida College of Veterinary Medicine.
When the results came back this summer, they revealed signs of inflammation in the dolphin’s brain and the surrounding tissues, Dr. Walsh said. Scientists have previously documented brain inflammation in fox kits infected with the virus, which can cause neurological symptoms in birds and mammals.
Subsequent laboratory testing turned up Eurasian H5N1 in the dolphin’s brain and lungs. “The brain tissue really showed a high level of virus,” Dr. Walsh said.
Whether the virus contributed to the dolphin’s death remains unknown, as does precisely how the animal contracted it. But it is not hard to imagine a young dolphin investigating an ailing bird near the shoreline, Dr. Walsh said, adding: “These animals are always curious about their environment and checking things out. So if he came upon a sick, either dying or dead, bird, he might be very curious about it. He might mouth it.”