In early September, scientists at the University of Florida confirmed that a bottlenose dolphin, found dead in a canal on the Gulf Coast in March, carried a highly pathogenic kind of avian influenza. Its brain was inflamed.

True to its label, this virus is skilled at infecting birds, but it sometimes goes farther afield. A few months after the dolphin’s death, another mammal, a porpoise, was found stranded and weak on the west coast of Sweden. It subsequently died, bearing the same virus. Between these events, there was another concerning case in the United States state of Colorado, when a man tested positive for bird flu. He was a state prison inmate, at work in a pre-release job that involved culling birds on a poultry farm where the infection had struck.