Inventory of Trematode Cercariae Infections in Freshwater Snails in Chitwan and Nawalparasi Districts and Trematode Infections in Domestic Elephants of Sauraha (Minor Study)

Abstract

Between August 2007 to November 2007, freshwater snails were collected from different parts of Nawalparasi and Chitwan districts of Nepal to determine the occurrence of larval trematodes. A total of 2525 snails, representing ten species, were collected from 6 habitats and 89 (3.52%) harboured patent trematode infections. Gabbia orcula had the highest overall prevalence of infection (6.5%) followed by Indoplanorbis exustus (4.5%). Whereas no infection was recorded in Bellamya bengalensis, Brotia costula, Parreysia sp.; Pila globosa and Segmentina sp. The highest percentage of infection (6.23%) was found in small temporary ponds. Five morphologically distinguishable types of cercariae were identified. The Amphistome was the most common type of cercaria recovered, contributing 43.82% of all infections. Xiphidiocercaria contributed 42.7% of all infections and were recorded from four different snail species. The Brevifurcate-apharyngeate (Schistosoma) cercaria (7.87%), Clinostomoid cercaria (3.37%) and Longifurcate-pharyngeate (Strigea) cercaria (1.12%) were recorded only from the Indoplanorbis exustus. A Indoplanorbis exustus with double infection (Amphistome and Schistosoma) was also recorded. This study also reported the presence of the eggs of Schistosoma sp. and Fasciola sp. in captive elephants of Chitwan.