An epidemiological study of visceral leishmaniasis in North East Ethiopia using serological and leishmanin skin tests

BACKGROUND: In Ethiopia, visceral leishmaniasis (VL) is caused by Leishmania donovani. The estimated country-wide incidence of VL in Ethiopia is 3700–7400 cases/year. The balance between anthroponotic and zoonotic transmission is still unknown even though most authors believe that visceral leishmaniasis in East Africa is anthroponotic. Asymptomatic leishmania infections occur more frequently than clinically apparent visceral leishmaniasis cases. The aim of this study was to determine the prevalence of asymptomatic VL infection and assess the degree of exposure among residents in Raya Azebo Woreda villages where cases of VL were recently reported. METHODS: A community based cross-sectional survey was conducted in 2013 between 1(st) of May and 25(th) of July. A total of 1099 individuals living in 314 households were included in the study. Socio-demographic and clinical data were collected from each of the participants and venous blood was also collected for the detection of antibodies to visceral leishmaniasis using Direct Agglutination Test. Leishmanin skin test was performed to detect the exposure to the parasite. Data was entered into excel and exported to SPSS version 17 for statistical analysis. Chi-square and the corresponding p-values were used to determine the statistical significance of the proportions/ratios obtained from the cross tabulated data. A p-value < 0.05 was considered statistically significant. RESULT: A total of 1099 study subjects comprising 401 males and 698 females were included in the study. The overall positive leishmanian skin test and sero-prevalence rates respectively were 9.08% and 0.87%. The difference in LST positivity by age group and sero-prevalence by sex were statistically significant (P <0.01 and P<0.05 respectively). Out of the 9 sero-positive individuals, 7 had no history of travel to visceral leishmaniasis endemic areas out of Raya Azebo. CONCLUSION: In general our results suggest occurrence of VL in the study area is, very low. Our survey also indicates that due to the low incidence of the disease, and lack of awareness, some patients remain under diagnosed.