Epidemiological studies on some trematode parasites of ruminants in the snail intermediate hosts in three districts of Uttar Pradesh, Jabalpur and Ranchi

Seasonal prevalence of 5 trematode parasites in the 4 snail species, viz. Lymnaea auricularia, L. luteola, Gyraulus convexiusculus and Indoplanorbis exustus for the years 2012–2014 was studied in 3 districts of Uttar Pradesh and in Jabalpur and Ranchi districts of Madhya Pradesh and Jharkhand, respectively. Intramolluscan larval stages of Fasciola gigantica, Explanatum explanatum, Paramphistomum epiclitum, Fischoederius elongatus and Schistosoma spindale were identified using ITS-2, 28S rDNA, 12S mitochondrial (mt) DNA and Cox I markers. F. gigantica infection in L. auricularia had a significant (P<0.05) occurrence in the winter season followed by rains. Seasonality of P. epiclitum transmission in I. exustus was observed with significant occurrence of its infection in the rainy season followed by a sharp decline in other seasons. Prevalence of S. spindale infection in I. exustus was insignificant in 3 districts of Uttar Pradesh but highly prevalent in other 2 districts. Infection with F. elongatus in L. luteola was recorded in different seasons. G. convexiusculus were screened for E. explanatum and Gastrothylax crumenifer infection and a significant rate of infection with E. explanatum was observed in the rainy season. Climatic factors including temperature and rainfall influence the distribution of snail populations and transmission of trematode infections by these snail intermediate hosts.