Cysticercus fasciolaris (Taenia taeniaeformis Larval Stage) in Urban Rats with Illustration of Histopathological Changes in the Liver

Introduction: Cysticercus fasciolaris is the larval stage of the cestode Taenia taeniaeformis, whose definitive hosts are cats. Rodents and very rarely humans act as intermediate hosts. Here, we investigated the rate of infection among urban rats in the north of Khuzestan province, southwest of Iran, and described the histopathological changes in the liver of infected animals. Methods: One hundred eight rats were collected from the cities Dezful, Sush, and Andimeshk in the north of Khuzestan province during 2014-2015. The rats were sacrificed, dissected, and their livers were removed and examined macroscopically for the presence of the cyst, which were then cut open and inspected for larvae. The cysts of infected livers were examined for the histopathological changes and the recovered larvae were identified based on morphometric features. Results: Out of 108 rats examined, 8 (7.4%) had small to moderate size cysts. Each cyst had two layers and contained one larva of C. fasciolaris. The scolex of the larvae had four suckers and a rostellum armed with two rows of hooks. The infected livers had multiple cysts and liver parenchyma necrosis or neoplastic evidence were not seen in the tissue sections. Conclusion: The small size cysts indicated actue infection, which may explain the absence of sarcoma as well.