Land-use effect on the distribution of freshwater snail intermediate hosts and schistosomiasis infection in omo-gibe river basin, southwest of Ethiopia

Abstract

Introduction: In Omo-Gibe river basin the extent of land-use is high due to anthropogenic activities this leads to the invasion of freshwater snail intermediate hosts distribution. Agricultural and human settlement areas increased the whole periods. Land-use change leads to the invasion of freshwater snail intermediate hosts which causes schistosomiasis. Most intermediate snail hosts of human Schistosome parasites belong to the two genera Biomphalaria and Bulinus. In Addition, Lymnea is another important host of Fasciola which cause Faciolasis in domestic animals and human. This study informs snail intermediate host distribution and infection prevalence. Objective: to determine and map the effects of land use on the distribution of freshwater snail intermediate hosts, snail infection, and schistosomiasis infection prevalence in Omo-Gibe River basin, Southwest Ethiopia. Methods and Materials: A cross-sectional study was conducted from March 22, 2016 to May 05, 2016. We surveyed 130 sampling stations from different sites which include rivers, lakes, dams, spring, wetlands and irrigation ditches of Omo-Gibe river basin. ArcGIS software of version 10.3.1 was used to map snail distribution. ANOVA is used to analyze the mean comparison and post Hock for mean separation using SPSS package of version-20 where chi-square and F-test are applied to evaluate significance. Prevalence of cercaria infection in snails and schistosoma infection rates in humans were determined by descriptive statistics. Results: Over all 2559 snail intermediate host collected from 130 surveyed stations in Omo-Gibe river basin, which belonged to four genera and seven species. In addition one was in family level. Of these snail intermediate hosts, 1749 belonged to the genera of Bioamphalaria, Lymnea, Bulinus and Physa. Biomphalaria pfeifferi was the predominant accounted for 35.4% of the total snail collection and 39.2% were sampled significantly (p=0.000) from lakes, wetlands, rivers and irrigation ditches. The highest collection of Biomphalaria pfeifferi (89.2%) was from rivers. Majority of cercaria shading recorded on L. natalensis (10.1%) next to B. pfefferi (85.3%) insignificant association (P=0.297) to land-use types. The overall prevalence of S. mansoni was 9.2% and the highest S. mansoni prevalence (31.1%) was recorded in Seto-Yido schoolchildren which is insignificantly (P=0.300) associated to land-use. Conclusions and Recommendations: In general the freshwater snail intermediate hosts: Biomphalaria, Bulinus and Lymnaea were collected from lakes, rivers, wetlands, irrigation ditches. Lymnea was predominant and infected snail next to B. pfefferi. For schistosoma study only S.mansoni prevalence was (9.2%) recorded. The study had shown negative for S. haematobium. From the finding, the study seams to show the foci of snail intermediate hosts distribution and snail infection; therefore, it helps stake-holders to develop monitoring and mass treatment measure at snail hot spot area and further studies will provide better insight for new infestation and indication of schistosomiasis prevalence in the same study area and other parts of Ethiopia.