Risk mapping of visceral leishmaniasis: the role of local variation in rainfall and altitude on the presence and incidence of kala-azar in eastern Sudan.
1Department of Zoology, Faculty of Science, University of Khartoum, Khartoum, Sudan. 2Khartoum College of Medical Sciences, Aljerief West, Khartoum, Sudan. 3Commission for Biotechnology and Genetic Engineering, National Centre for Research, Ministry of Science and Biotechnology, Khartoum, Sudan. 4Federal Ministry of Health, Khartoum, Sudan. 5Tabarakallah Hospital, Ministry of Health, Gedaref, Sudan. ABSTRACT A cross-sectional survey was carried out in Gedaref state, eastern Sudan to investigate the prevalence of positive leishmanin skin tests and environmental factors related to Leishmania donovani infection. A total of 3835 people living in 11 villages in 3 regions were screened. Soil types and tree densities were determined in 33 villages inhabited by 44 different tribes. The highest rates of positive skin tests were in Rahad region (33.9%), Atbara (21.6%) and Gedaref (10.6%), with an average of 21.1% for the state. Risk of infection by L. donovani varied significantly between different tribes. Higher densities of Acacia and Balanites spp. trees were in Masaleet villages, suggesting that the relatively high risk of L. donovani exposure in this tribe is due to environmental factors.