Ecology and Pathology of Amphibian Ranaviruses
Vol. 87: 243–266, 2009 DISEASES OF AQUATIC ORGANISMS Published December 3 doi: 10.3354/dao02138 Dis Aquat Org OPENPEN ACCESSCCESS REVIEW Ecology and pathology of amphibian ranaviruses Matthew J. Gray1,*, Debra L. Miller1, 2, Jason T. Hoverman1 1274 Ellington Plant Sciences Building, Center for Wildlife Health, Department of Forestry Wildlife and Fisheries, Institute of Agriculture, University of Tennessee, Knoxville, Tennessee 37996-4563, USA 2Veterinary Diagnostic and Investigational Laboratory, College of Veterinary Medicine, University of Georgia, 43 Brighton Road, Tifton, Georgia 31793, USA ABSTRACT: Mass mortality of amphibians has occurred globally since at least the early 1990s from viral pathogens that are members of the genus Ranavirus, family Iridoviridae. The pathogen infects multiple amphibian hosts, larval and adult cohorts, and may persist in herpetofaunal and oste- ichthyan reservoirs. Environmental persistence of ranavirus virions outside a host may be several weeks or longer in aquatic systems. Transmission occurs by indirect and direct routes, and includes exposure to contaminated water or soil, casual or direct contact with infected individuals, and inges- tion of infected tissue during predation, cannibalism, or necrophagy. Some gross lesions include swelling of the limbs or body, erythema, swollen friable livers, and hemorrhage. Susceptible amphi- bians usually die from chronic cell death in multiple organs, which can occur within a few days fol- lowing infection or may take several weeks. Amphibian species differ in their susceptibility to rana- viruses, which may be related to their co-evolutionary history with the pathogen. The occurrence of recent widespread amphibian population die-offs from ranaviruses may be an interaction of sup- pressed and naïve host immunity, anthropogenic stressors, and novel strain introduction.
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