Effects of climatic factors on prevalence of developmental stages of Fasciola gigantica infection in Lymnaea snails (Lymnaea auricularia var rufescens) in Bangladesh

The present study was conducted to investigate the prevalence of developmental stages of Fasciola gigantica infection in Lymnaea snails and their populations in Sylhet region of Bangladesh. A total of ۱۸۶۵ Lymnaea snails were collected and examined, of which ۵۶ (۳%) were found to having infected with developmental stages of Fasciola gigantica. Only ۴.۰۸% infected of ۵۱۵ snails were collected from Biswanath Upazilla followed by ۳.۱۶% of ۴۴۳ from Beanibazar, ۲.۵۳% of ۳۹۶ from Balaganj then ۲.۴۰% of ۲۹۲ Jaintapur Upazilla and the lowest ۱.۸۳% of ۲۱۹ from Sylhet Sadar. Month-wise data, the prevalence of snail infections was observed to be the highest in May (۵.۰۶%) and August (۵.۶۱%) and the lowest in March (۰.۷۴%) and February (۰.۶۸%). However there was no infection observed through November to January. Seasonal prevalence of the developmental stages of F. gigantica infection in Lymnaea snails was also studied. Highest prevalence (۴.۶۳%) was recorded during rainy season and lowest prevalence (۰.۷۶%) was recorded during winter season. The study revealed that the developmental stages of F. gigantica infection in snail populations decreases from November to January and increases from February to October and highest in August and September in Sylhet region of Bangladesh.