The prevalence and risk factors for hydatidosis in man, sheep and goats in northwesternTurkana district, Kenya

Abstract

Hydatidosis is a cyclo-zoonotic disease caused by larval stages of the parasitic tapeworms of the genus Echinococcus. The disease is a public health importance among the Turkana pastoral community. The previous estimates of hydatidosis prevalence in livestock in northern Turkana have recorded inconsistent estimates over time because they depended on slaughter-house data. The socioeconomic aspects of hydatidosis including knowledge, attitudes and practices (KAP) that favour the transmission of the disease in endemic setting are inadequately studied. The objectives of the present study were to estimate the prevalence of hydatidosis in man, sheep and goats and assess level of agreement between ultrasonography and Enzyme Linked Immunosorbent Assay (ELISA) tests. Others were to assess the risk factors associated with the disease and map out the prevalence in the study area. The study was carried out in northern part of Turkana District, conveniently stratified into three regions: Oropoi, Mogilla and Kibish. A total of 93 sheep, 467 goats and 982 people were screened for hydatid cysts by ultrasonography. In this study, blood samples were collected from the animals screened by ultrasound and serum separated for laboratory analysis. ELISA test was applied to all; the sera from the livestock in laboratory analysis. Twelve dogs were sacrificed and postmortem examination carried out in order to assess the worm burden. The potential risk factors associated with the hydatid disease in man and his livestock were assessed using questionnaires, observations and interviews to 61 household heads. Global Positioning System (GPS) was used to take co-ordinates of the sampled points and the adakaar locations. The results showed that 4.3%, 1.5% and 1.6% of sheep, goats and human screened were positive for hydatidosis, respectively using ultrasonography. The ELISA results showed that 81% and 37% of sheep and goats were infected, respectively. The computed Kappa statistic was 0.02 indicating that the two tests did not agree well. There was mild to moderate infections in dogs with Echinococcus granulosus and all of them had Taenia hydatigena worms on postmortem examination. The potential risk factors associated with hydatidosis were analyzed in the multivariate analysis. The independent variable which was significantly (P<0.05) associated with the outcome of the hydatid disease in human was the clan. Other factors analyzed in this study were not significant though their contributions towards high infection rate were observed in the univariate analysis. The region and presence of a dog in the household were the potential risk factors that significantly predicted outcome of hydatidosis in sheep in the multivariate analysis. Three most important potential risk factors associated with hydatidosis in goats in the analysis were; region, the number of goats, and the number of camels slaughtered in ceremonial festivities. Thematic maps of the sampled locations, prevalence of hydatidosis in man and the three species of domestic livestock have been produced. Based on the findings of this work, Echinococcus granulosus cycle is still going on in Turkana despite intervention measures .which are in place. Overall, the prevalence of hydatid disease in humans has gone down except in some specific areas including Nanam and Kaikor locations of northern part of Turkana District. In sheep and goats there was little change in prevalence of hydatid disease. Further research is recommended on the Turkana pastoralists clan differences and their contribution to the transmission cycle of the hydatid disease.