First posted on 02-24-2012
Eastern massasauga rattlesnakes are not native to the Ozarks. Their closest proximity to our region is a small section of northeastern Missouri, and parts of southern Illinois. But they are significant because a fungus not normally seen in the wild presents an unexpected threat that has killed several snakes already.
The eastern massasauga has been in decline throughout southern Illinois and in other states as a result of habitat loss and environmental stresses. These snakes inhabit wetland areas, scrub swamps and grassy meadows. A candidate for protection under the Endangered Species Act, eastern massasauga rattlesnakes have had a difficult time surviving in any region they occupy.
Matthew Allender, a biosciences instructor and wildlife veterinarian at the University of Illinois, led a health investigation after several snakes turned up with severe, disfiguring lesions on their heads. Allender identified Chrysosporium as the pathogen that killed the eastern massasaugas he examined. Chrysosporium is a fungus not uncommon in the pet reptile industry, but not seen in the wild. Previous studies of eastern massasaugas had not revealed the deadly fungus.
“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.”
Allender also commented that Chrysosporium is emerging as a dangerous infection in humans who have weakened immune systems.
After presenting his findings, Allender said he heard from scientists about similar infections in other snake populations, principally in the northeastern United States.
“They seem to be having a similar problem in timber rattlesnakes in New Hampshire and Massachusetts,” Allender said. The reported symptoms – facial swelling, ulcers and malformations of the jaw – are the same, he said. As with the eastern massasauga, all these infections have only occurred within the last five years.
“Fungal pathogens have been increasingly associated with free-ranging epidemics in wildlife, including the well-known effects of Batrachochytrium dendrobatidis on frog populations globally and white-nosed syndrome in bats,” Allender wrote in a December 2011 report in the journal Emerging Infectious Diseases. “Both of these diseases cause widespread and ongoing deaths in these populations that seriously threaten biodiversity across the United States.”
Allender describes this occurrence of fungal infection in endangered snakes as a “yellow flag” that warrants more study.
“Wildlife diseases and human health are not that different,” he said. “And often wildlife are our window into a weakened environment that leads to disease in both people and animals.”
Photo courtesy of Matthew Allender.
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