The Epidemiology of Snake Fungal Disease in Eastern Massasaugas over the Last 10 Years

Snake fungal disease (SFD), caused by the fungus Ophidiomyces ophiodiicola, emerged as a wildlife disease threat over the last 10 years and specifically may threaten the conservation of free-ranging Eastern Massasaugas. Historical records and museum collections have now indicated that SFD was present in some populations in Illinois at least a decade before its description in the literature. The disease syndrome involves clinical signs ranging from minor raised and thickened scales to severe crusts or ulcers on the head and body and can cause death in severe cases. The disease has been found to affect at least 31 snake species. As part of ongoing surveillance for SFD, the Wildlife Epidemiology Lab routinely tests samples for the presence of O. ophiodiicola using qPCR. Since 2013, we have tested over 2000 snake samples from 69 species. In total, 616 positive samples have been recorded across 31 species in 11 states. Despite the apparent sensitivity of pit vipers, only 12.5% (n=99/693) of Eastern massasaugas (Sistrurus catenatus) were positive, whereas nearly 60% (n=218/365) of water snakes (Nerodia sp.) were positive for O. ophiodiicola. Host factors, such as hematology and protein electrophoresis have demonstrated individual Eastern Massasaugas respond immunologically, but the basis for disease protection is unknown. This presentation will synthesize historical and existing knowledge of SFD in Eastern Massasaugas and plans for future efforts. Characterizing the epidemiology of this disease can improve future surveillance and management efforts that may mitigate its effects on snake populations worldwide.