Factors associated with Leishmania asymptomatic infection: results from a cross-sectional survey in highland northern Ethiopia

BACKGROUND: In northern Ethiopia the prevalence of visceral leishmaniasis is steadily rising posing an increasing public health concern. In order to develop effective control strategies on the transmission of the disease it is important to generate knowledge on the epidemiological determinants of the infection. METHODOLOGY/PRINCIPAL FINDINGS: We conducted a cross-sectional survey on children 4-15 years of age using a multi staged stratified cluster sampling on high incidence sub-districts of Amhara regional state, Ethiopia. The survey included a socio-demographic, health and dietary questionnaire, and anthropometric measurements. We performed rK39-ICT and DAT serological tests in order to detect anti-Leishmania antibodies and carried out Leishmanin Skin Test (LST) using L.major antigen. Logistic regression models were used. Of the 565 children surveyed 56 children were positive to infection (9.9%). The individual variables that showed a positive association with infection were increasing age, being male and sleeping outside [adjusted odds ratios (95% CI): 1.15 (1.03, 1.29), 2.56 (1.19, 5.48) and 2.21 (1.03, 4.71) respectively] and in relation to the household: past history of VL in the family, living in a straw roofed house and if the family owned sheep [adjusted OR (95% CI): 2.92 (1.25, 6.81), 2.71 (1.21, 6.07) and 4.16 (1.41, 12.31) respectively]. CONCLUSIONS/SIGNIFICANCE: A behavioural pattern like sleeping outside is determinant in the transmission of the infection in this area. Protective measures should be implemented against this identified risk activity. Results also suggest a geographical clustering and a household focalization of the infection. The behaviour of the vector in the area needs to be clarified in order to establish the role of domestic animals and house materials in the transmission of the infection.The authors gratefully acknowledge the financial support of the UBS-Optimus Foundation (www.ubs.com/optimus) via the Visceral Leishmaniasis and Malnutrition in Amhara State, Ethiopia project, and the Instituto de Salud Carlos III via the Tropical Diseases Research Network (RICET RD06/0021/0009 and RD06/ 0021/0000, www.ricet.es/en/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.S