Loggerhead sea turtles (Caretta caretta) have been designated a threatened species by the Endangered Species Act (US Department of Commerce, 1976). Classical anatomic-pathologic methods are being used to determine diseases and causes of death.

Forty-nine C. caretta accessions from the Atlantic seaboard (Florida to Massachusetts) were examined at the Marine Pathology Laboratory, University of Rhode Island, from March through December, 1980. Three genera of Spirorchids (blood flukes) were found in 14 of the 49 accessions (28.5%).

In heavily infected animals gross signs included cachexia, anemia and enteritis. Histopathological lesions were similar to those present in homoiotherms with Schistosomiasis. Granulomatous gastritis, enteritis, hepatitis, pneumonitis, and nephritis were present. Acute and chronic vasculitis accompanied ova migrations. Infected animals had a severe hepatic hemosiderosis, indicative of the anemia observed grossly.

Evidence is presented that Spirorchidiasis is prevalent in sub-adult loggerhead sea turtles, is responsible for extensive lesions and may be responsible for significant debilitation and mortality.