Prevalence of cercarial infection in Biomphalaria snail hosts and Schistosoma mansoni infection among fishermen in the shore of Lake Hawassa and Tikur Wuha River, Southern Ethiopia

Abstract

Background: Freshwater snails serve as intermediate hosts for different digenetic trematode species that cause snail borne diseases of humans and animals. Different environmental factors and human activities affect the abundance and infection rate of the snails. Environmental conditions in Africa favor the growth of snail and trematode which has the potential to become a public health problem in many countries. In addition to environmental conditions, there are other different factors that cause a high prevalence of schistosomiasis, these are water resources development projects, irrigation, fishing, population increase, and migration. These conditions favor infection of freshwater snail and increase the risk of schistosomiasis infection. Objective: the main objective is to determine prevalence of cercarial infection in Biomphalaria snails and S. mansoni infection among fishermen in Lake Hawassa and Tikur Wuha River in 2020. Methods and materials: The snails were collected from 26 sampling sites and examined for cercarial infection using natural shedding method. The cercariae were identified morphologically. In the surveyed sites the data on environmental factors, human disturbance, demographic and behavioral factors were collected. Stool samples from fishermen were examined for S. mansoni infection. To determine factors influencing the prevalence of snail infection PCA was used. Chi- square was used to assess the association between S. mansoni infection and the risk factors. Results: The study indicate that only Biomphalaria sudanica snail species were infected with cercaria. Five different types of cercaria were recorded with a total prevalence of 12.03%. Of which BAD (human schistosome) cercariae were the dominant accounting 37.5 % of all recorded cercarial type. The prevalence of cercarial infection in snails positively influenced by BOD 5 , turbidity, total suspended solids, human activities, and habitat condition. The total prevalence of S. mansoni infection among fishermen was 14.7% and significantly associated with frequency of swimming and educational status. Conclusion and Recommendations: The prevalence of intestinal schistosomiasis was 14.7% among the fishermen which transmitted by the vector Biomphalaria intermediate host snails. The prevalence of cercarial infection in snails was high in this area which results high risk for the transmission of schistosomiasis. Therefore, an intervention programs should be focused on the snail control, provision of adequate sanitation, and health education to control the transmission of schistosomiasis.