Epidemiological Studies of Schistosomiasis in Jos South Local Government Area, Plateau State, Nigeria

Abstract

Schistosomiasis is a helminthic disease that affect many people all over the world causing illnesses that prevent people from farming and performing other activities, and at times gives rise to malignancies which are fatal. Between 1999 and 2004, some aspects of the epidemiology of schistosomiasis, were studied among 3190 inhabitants of Dogon-Karfe (the boundary with Jos North Local Government Area), Gigiring, Anglo-Jos Bukuru, Vom, Zawan, Mararaba-Jama’a and Farin-Lamba, all in Jos South Local Government Area, Plateau State Nigeria. Their faeces and urine were examined microscopically for eggs of schistosomes. The faecal samples were prepared using the method described by Allen and Ridley (1970) while the urine samples were prepared using the method of Dazo and Biles (1974). Thirteen (13) (0.20%) of the entire volunteers had eggs of schistosome in their stool and 8(0.13%) recorded presence of eggs in their urine samples. The streams and irrigation systems within the area were surveyed for the intermediate hosts (snails). The snail vectors were examined for cercariae by exposure to sunshine for 30 minutes. Of the 1081 snails collected from these streams only 85(7.86%) excreted cercariae. The difference in infection of the snails by cercariae in different sites were statistically significant (P<0.05). Infection rates of individuals in different age groups by schistosomiasis, infection rates of individuals using different types of water supply (bore hole, pipe- borne, and stream) by schistosomiasis and infection rates of individuals using different types of toilet facilities (water closet system, pit and bush), by schistosomiasis were statistically significant (P<0.05). The differences in infection rates of the sexes, individuals in different religious groups, individuals in different occupational groups by schistosomiasis, infection rates of individuals within the seasons (wet and dry) by schistosomiasis and the infection rates of individuals in the different locations by schistosomiasis were not statistically significant (P>0.05) in all. All the infected snails were Lymnea natalensis while the other species, Bulinus globosus and Biomphalaria pfeifferi which were also encountered during the study were not all infected by cercariae. Water quality parameters pH, conductivity, alkalinity, temperature, and dissolved oxygen were measured in the surveyed streams. The water quality seemed to have effect on the infectivity of the snails as out of the 1081 snails collected only 85 Lymnea species from Vom/ National Institute for Policy and Strategic Studies, Kuru stream with lowest pH of 5.5, and dissolvedoxygen content of 5.0mg/L-1 were found infected while 772 snails collected from other streams with higher values of these parameters were not infected. No snail intermediate host was seen in all the irrigation systems surveyed. From the results obtained, schistosomiasis was not endemic in the study area. Of other parasites encountered during the study, Entamoeba coli had the highest prevalence 358 (11.22%) followed by Entamoeba histolytica, 266 (8.34%) and the least Trichomonas vaginalis, 8(0.25%) among the Protozoa while among the other helminthes, hookworms had the highest prevalence of 393 (12.32%) followed by Ascaris lumbricoides, 192 (6.02%), Trichuris trichiura, 8(0.25%) and the least Enterobius vermicularis, 6 (0.19%). From the study, there is a declining prevalence of schistosomiasis in the study area.