LESIONS CAUSED BY CARDIOVASCULAR FLUKES (DIGENEA, SPIRORCHIDAE) IN STRANDED GREEN TURTLES (CHELONIA-MYDAS)

Evidence of infection with spirorchid flukes (Digenea: Spirorchidae) w as sought at necropsy of 96 stranded green turtles, Chelonia mydas, th at were examined during the course of a survey of marine turtle mortal ity in southeastern Queensland, Australia. Three species of spirorchid (Hapalotrema mehrai, H. postorchis, and Neospirorchis schistosomatoid es) were identified. Severe disease due to spirorchid fluke infection (spirorchidiasis) was implicated as the principal cause of mortality i n 10 turtles (10%), and appeared to be one of multiple severe problems in an additional 29 turtles (30%). Although flukes were observed in o nly 45% of stranded C. mydas in this study, presumed spirorchid fluke infection was diagnosed in an additional 53% of turtles, based princip ally on characteristic necropsy lesions and to a lesser extent on the histopathological detection of spirorchid eggs. Characteristic necrops y lesions included miliary spirorchid egg granulomas, which were obser ved most readily on serosal surfaces, particularly of the small intest ine. Cardiovascular lesions included mural endocarditis, arteritis, an d thrombosis, frequently accompanied by aneurysm formation. Resolution of thrombi was observed to occur via a combination of granuloma forma tion about indigestible components (spirorchid fluke egg shells) and e xteriorization through the vessel wall, which resulted in granulomatou s nodules on the adventitial surface. Septic aortic thrombosis complic ated by disseminated bacterial infection, observed in five turtles, wa s recorded for the first time. Egg granulomas were ubiquitous in turtl e tissues throughout this study. Although they generally appeared to b e mild or incidental lesions, they were occasionally associated with s evere multifocal granulomatous pneumonia or meningitis.