Gall bladder and extrahepatic bile duct changes in Opisthorchis viverrini-infected hamsters

Opisthorchis viverrini infection is associated with several hepatobiliary diseases, but few reports have described extrahepatic lesions in opisthorchiasis. We therefore sequentially investigated histological changes of the gall bladder and extrahepatic bile duct in hamsters infected with 25 (group 1), 50 (group 2) and 100 (group 3) metacercariae for up to 180 days. Acute inflammatory reactions, including congestion, neutrophil and eosinophil infiltration, occurred in the gall bladder as early as day 7 of groups 2 and 3 and on day 14 in group 1; the extrahepatic bile ducts exhibited the changes on day 3 post-infection (p.i.). Mononuclear cell infiltration, mucus hypersecretion and fibrosis were gradually observed thereafter. Active inflammation reached a plateau at approximately 60 days in all infected groups. The well-established chronic histological changes of the gall bladder and extrahepatic bile duct were fibrosis and mononuclear cell infiltration with lymphoid aggregation and, additionally, ductal dilatation for the latter. Overall, the pathological changes in the extrahepatic bile duct were more severe than those in the gall bladder for the same dose and period of infection. The results demonstrate that pathological changes in the gall bladder and extrahepatic bile duct do occur in O. viverrini infection and may be extrapolated to human infection.