Trematode Infections in Freshwater Snails and Seasonal Variations in Iringa and Arumeru Districts, Tanzania

Understanding of the larval trematode infections in snail intermediate hosts is essential in designing appropriate control measures. The current study was designed to determine larval trematode infection and seasonal variations in freshwater intermediate host snails Iringa and Arumeru Districts where trematode infections in cattle are endemic. A repeated cross-sectional study was adopted whereby Snails were collected three times a year (dry, early wet and mid wet). The selection of water bodies for sampling was based on random sampling and snails were collected by scooping method. The collected snails were identified based on the published morphological keys. A total of 2,016 snails were collected and 134 (6.6%) were found to be infected with trematode larvae. Six species of snails were identified that were Radix natalensis, Bulinus africanus group snails, Bulinus tropicus group snails, Bulinus forskalli group snails, Biomphalaria pfeifferi and Ceratophallous natalensis. Five morphologically different types of cercariae were identified that included gymnocephalous, amphistomes, mammalian Schistosoma, avian Schistosoma and Xiphidiocercariae. The findings on overall seasonal snail infection rates indicated low rate during the wet season while peak of infections were in the dry and early wet seasons. It is concluded that domesticated ruminants in the study areas are at high risk of getting infected with the trematodes (Fasciola and amphistomes) during dry and early wet seasons. Therefore, deworming of domesticated ruminants with an effective flukicide is recommended at the end of the wet season and followed by a treatment in mid dry season and the last treatment in early wet season.