Is it ovine cystic echinococcosis? Post-mortem inspection compared to laboratory analyses of lesions from a slaughterhouse in a hypo-endemic area of northern Italy

The larval stage of Echinococcus granulosus sensu lato causes cystic echinococcosis (CE), an important parasitic zoonotic disease infecting over an estimated one million people worldwide. Canids act as definitive hosts while livestock, mainly sheep, serve as intermediate hosts for the larval stage. Inspection at slaughter of intermediate hosts and destruction of affected organs play an important role in limiting parasite spread. The aim of the present study was to evaluate, over a 6-month period, the prevalence of CE in sheep in an hypo-endemic area for E. granulosus, as determined at slaughter and to verify diagnosis in the laboratory through gross morphological evaluation, histopathology and a multiplex end-point PCR. Sample collection was performed in an ovine slaughterhouse in northern Italy. Lungs and livers were examined visually and those with lesions compatible with CE according to the official veterinary control were then conferred to the laboratory. A total of 421 sheep were examined and CE was suspected in 101/421 (24 %). Following incision, however, only 36/101 showed lesions with morphological features of CE. Histology and end-point PCR were positive for E. granulosus in only 25/36 sheep, highlighting the CE prevalence at 5.9 % (25/421). Results suggest that current inspection at slaughter based on visualization alone may over-estimate CE prevalence in particular in hypo-endemic areas.