Trematode Infections in Freshwater Snails and Rainfall Patterns in Ibadan North Local Government Area, Oyo State, Nigeria

Abstract

The extent and intensity of parasitism is known to be affected by climatic conditions. Climate changes among other factors have been confirmed to exert more influence on helminths and thus, on the diseases caused by helminths. Freshwater snails serve as specific intermediate hosts for trematodes of medical and veterinary importance and snail ecology is important in the transmission of the parasites. Snail-borne trematodiasis are heavily dependent on the environment for dissemination and are greatly affected by climate. Correlating rainfall patterns, snail abundance and trematode infection have been known to aid in the design of control models for snail-borne diseases. Freshwater snail samples were collected from August to December in years 2012 and 2014 to determine abundance and prevalence of trematode infection. Rainfall data for the study period was obtained from the Department of Geography, University of Ibadan. A total of 550 freshwater snails samples were collected in 2012 and 480 in 2014. The snails identified were Physa, Lymnaea, Bulinus and Melanoides species. Examination for trematodes cercariae was carried out using the crushing method. In 2012, 18 snails out of 550, (3.3%) were infected with trematode species with evidence of cercariae release while 0% was recorded in 2014. The total recorded rainfall for the study period in 2012 and 2014 was 35.20mm and 303.40mm respectively. This result showed that rainfall has an effect on the survivability and availability of freshwater snails and thus could be a factor in determining the prevalence of snail-borne infections.