Long-term population studies of the snake -- in Illinois and elsewhere -- had never turned up evidence of debilitating fungal infections. But in 2008, biologists studying the snake reported to Allender that they had found three sick snakes in a park in southern Illinois, all with disfiguring lesions on their heads. The snakes died within three weeks of their discovery. A fourth snake with a similar syndrome was discovered in the same park in the spring of 2010.

Allender conducted necropsies on the snakes and identified the pathogen that had killed them: C hrysosporium, a fungus that plagues portions of the pet reptile industry but is not normally seen in the wild, he said.

"Chrysosporium causes disease in bearded dragons and in other snakes and it's a bad bug," Allender said. "We see it in captive animals worldwide, but we don't typically find it in free-ranging animals."

Chrysosporium also is emerging as a dangerous infection in humans with weakened immune systems, he said.
Shortly after he first presented his findings at a meeting of the Fish and Wildlife Service, Allender heard from other biologists about similar infections in snakes in the northeast United States.