Effects of Abiotic and Biotic Factors on the Snail Predator, Procambarus clarkii, Girad (Decapoda: Cambaridae): Implications for Schistosomiasis Control in Kenya

Abstract

Background & Objective: There is increasing interest not only in the control of schistosomiasis but also, the physico-chemical parameters responsible for seasonal variation in transmission of the disease and the effect they may have on both the predator, crustacean, and the snails. In Africa, one of the major challenges of studying these parameters is lack of equipment that can be used in-situ. In the present study, we sought to assess the effects of physic-chemical parameters of schistosomiasis transmitting snails and their natural predators, crayfish. Methods: Cross-sectional study design employing quantitative techniques for data and analysis collection. Study was conducted in Machakos-Kitui area of Kenya within the river Athi drainage basin. Study subjects include snails inhabiting the study streams. Results: 161 snail out of 2325 total sampled snails on shedding turned out to be positive for mammalian schistosomes representing a prevalence of 6.9%. The pH, water and temperature did not vary significantly in the different streams (P-value = 0.7524 at P < 0.05). Increase in water temperature showed significant positive correlations with B. pfeifferi (r 2 = 0.665; P < 0.01) and B. nasutus (r 2 = 0.0.665; P < 0.05), Lymneanatalensis (r 2 = 0.589; P < 0.010). The overall mean pH value was 7.8 ± 0.8 with values ranging from 7.34 in KwaMutanga River to 8.6 recorded in Kyanguli River. Interpretation & conclusion: While planning snail sampling and initiation of biological control strategies, abiotic and biotic factors should be borne in mind as they seem to play a key role in the success of schistosomiasis intervention, especially at the intermediate host level.