Massive hepatic trematodosis in 5 juvenile bald eagles.

Hepatic trematodosis by opisthorchiid flukes has been reported sporadically in North American fish-eating raptors. Bald eagles () infected by these flukes often have various degrees of granulomatous cholangitis, pericholangitis, necrosis of adjacent hepatocytes, and subsequent hepatic fibrosis. Species identification has been complicated by the inability to dissect intact specimens from liver tissue. Between 2007 and 2018, 5 juvenile bald eagles with massive hepatic trematodosis were identified at autopsy. Histologically, flukes were non-spinous. Parasitologic identification revealed ventral suckers (80-93 µm diameter), and uteri containing golden, operculated eggs (~25.0 × 12.0 µm). An unfixed frozen liver sample of one eagle was analyzed by PCR and DNA sequencing targeting the large subunit rRNA, ITS region, and genes of the parasite. The fluke DNA sequences shared 99.6%, 98.4%, and 87.0% similarity, respectively, with , a newly described opisthorchiid species infecting the liver and pancreas of fish-eating birds in Europe and Asia. Infection by is highly pathogenic in several piscivorous bird species. The clinical significance of trematodosis in our 5 cases is uncertain because all birds had comorbidities.