RESUMO
The importance of marine snails in the transfer of cercariae to fish as a provenance of zoonoses should be considered.Parasitic studies in marine snails have been uncommon in Saudi Arabia. In the present study, 550 Nerita genus of marinesnails were monthly and randomly collected from January to December 2016 from Obhor bay, Saudi Arabia. The snailswere subjected to light. They were crushed to evaluate the presence of larval trematodes. PCR technique was performedusing the internal transcribed spacer region of ribosomal DNA (ITS-rDNA) which has been a specific primer to detect theextent of larval trematode infection in some snails infected as positive control samples and all non-infected snails to assess ifthey were infected or not. PCR technique showed a high prevalence of infection (55.82%) than the classical methods(21.45%). These studies can help in collecting data on the ecological importance of the distribution of disease insympathetic fish, and the transmission of digenean trematodes disease through snails. Moreover, they can be useful inpreventing and control of fish and human diseases.