Quarterly Wildlife Mortality Report
Written and compiled by members of the U.S. Geological Survey National Wildlife Health Center - Wildlife Epidemiology & Emerging Diseases Branch.
Large Trematode-caused Red-eared Slider Mortality in Louisiana
An extensive mortality event involving red-eared sliders (Trachemys scripta elegans) occurred in multiple locations across Acadia Parish in southern Louisiana. Mortality was first reported in February 2017 with the number of dead sliders likely in the hundreds. Morbid sliders were observed swimming in circles and exiting the water onto levees. They were lethargic and unable to flee when approached and had signs of respiratory disease including clogged nares and open mouth, shallow breathing. Healthy fish, crawfish, birds, frogs, and salamanders have been observed in the ponds with affected sliders.
The USGS National Wildlife Health Center (NWHC) examined several dead sliders submitted by the Louisiana Department of Wildlife and Fisheries (LDWF) and found severe pathology associated with a trematode in the genus Spirorchis. Internal lesions were found in brain, lung, spleen, and vascular system tissue associated with granulomas surrounding large numbers of trematode eggs. Spirorchis trematodes of turtles have a complex life cycle with turtles as the definitive host and snails as an intermediate host. Turtles examined at the Southeast Cooperative Wildlife Disease Study (SCWDS) and the Louisiana State University (LSU) Animal Disease Diagnostic Laboratory found similar evidence of trematode infection. Spirorchis trematodes are common parasites of North American turtles; it is currently unknown why they have caused such an extensive mortality event in this instance.
Salmonellosis in Florida Cardinals
Citizens throughout Florida’s Panhandle region (Jefferson, Santa Rosa, Duval, and Holmes Counties) have recently reported northern cardinal (Cardinalis cardinalis) mortalities. Clinical signs have included lethargy, limited flight, and sitting on the ground for a few hours before death. While more than 50 cardinals have been reported dead since February 1, 2017, other common passerine songbirds have been largely unaffected. Mortality events have been primarily reported by citizens with backyard birdfeeders. The USGS National Wildlife Health Center (NWHC) recently identified salmonellosis as the cause of death for two cardinals found dead at a Duval County backyard feeder and submitted to NWHC by the Florida Fish and Wildlife Conservation Commission. Salmonella transmission at birdfeeders typically occurs through direct bird-to-bird contact, contact with contaminated environments, or contaminated food. High densities of birds at feeders can increase the risk of salmonella outbreaks. Actions to reduce risk of infectious disease transmission at feeders include placing additional feeders to reduce crowding, routinely cleaning birdfeeders with a 10% bleach solution, and removing waste seed that accumulates under feeders.
Canine Distemper in Wisconsin
Beginning mid-March, 2017, the Wisconsin Department of Natural Resources (WI DNR) received reports of unusual mortality involving raccoon (Procyon lotor), gray fox (Urocyon cinereoargenteus), and striped skunk (Mephitis mephitis) occurring in two counties in southeastern Wisconsin. Following submission of two raccoons, a gray fox, and a striped skunk to the USGS National Wildlife Health Center (NWHC) canine distemper virus was determined to be the cause of death (with rabies ruled out). The Wisconsin Veterinary Diagnostic Laboratory and the Wisconsin State Laboratory of Hygiene collaborated on this diagnosis. The WI DNR continued to receive reports of unusual small mammal mortality through early June including cases in central and northern Wisconsin counties. Similar suspected distemper outbreaks in the spring of 2017 involving raccoons have been reported and investigated by the Minnesota Department of Natural Resources (six counties) and Virginia Department of Game and Inland Fisheries (two counties).
Distemper is a highly contagious, systemic, viral disease that infects a wide variety of mammalian species with domestic dogs considered to be the natural reservoir species. The disease is common and can cause significant outbreaks in susceptible wildlife species. Vaccination is essential for the prevention of disease and outbreaks in domestic dogs. Because the clinical signs of distemper can mimic rabies, contact with sick animals should be avoided. People and their domestic pets/livestock should avoid contact with sick or dead wildlife and contact the appropriate wildlife officials in their area for further guidance.
To view, search, and download historic and ongoing wildlife morbidity and mortality event records nationwide visit the Wildlife Health Information Sharing Partnership event reporting system (WHISPers) online database: http://www.nwhc.usgs.gov/whispers/
To request diagnostic services or report wildlife mortality: http://www.nwhc.usgs.gov/services/