Acute hepatic-stage infection with Cysticercus tenuicollis in Hu sheep from northeastern China: a case report.

Acute hepatic-stage infection with Cysticercus tenuicollis is rarely captured at necropsy and may be overlooked, as larvae typically migrate from the liver to the peritoneal cavity as the infection progresses. Here, we report sudden deaths in 3-4-month-old Hu sheep from a farm in Daqing, northeastern China, and describe the etiological agent and hepatic lesions. Necropsy revealed numerous translucent cystic lesions adherent to the hepatic capsule and diffuse intraparenchymal cystic lesions with multifocal hemorrhagic tracts. Hepatic histopathology showed disrupted lobular architecture with hepatocellular degeneration and lysis, hemorrhage, fibrosis, and lymphocyte-predominant inflammation. Cysticerci recovered from the liver were milky-white, oval to subspherical vesicles containing clear fluid, measuring 2.4–4.8 mm in length, no scolex was observed. For molecular confirmation, the ribosomal internal transcribed spacer (ITS) region was amplified and sequenced, yielding a 1269 bp fragment with 99.6% identity to Taenia hydatigena. Phylogenetic analysis using Maximum Likelihood method showed the isolate clustered within reference T. hydatigena clade and differentiated it from Echinococcus spp. and Moniezia spp. Following confirmation, praziquantel was administered to the remaining flock (15 mg/kg, single oral dose) and dog-focused biosecurity was implemented, no further deaths occurred during a 4-week follow-up. This case highlights an acute hepatic-stage presentation of C. tenuicollis in juvenile Hu sheep and supports prompt diagnosis and prevention in affected flocks.