Asymptomatic Leishmania infantum infections in humans living in endemic and non-endemic areas of Croatia, 2007 to 2009

The prevalence of asymptomatic leishmaniasis in the general population of Croatia has not been studied to date. To assess the prevalence of Leishmania infantum specific IgG antibodies among immunocompetent residents of Croatia, sera from 2,035 persons (eastern coast of Adriatic Sea, n=1,186; Adriatic islands, n=653; mainland, n=196), were tested by an enzyme immunoassay. A total of 231 (11.4%) persons had anti-Leishmania antibodies. Multivariate analysis revealed that seropositivity was associated with geographic location and age. Residents of coastal areas and islands were significantly more seropositive than mainland residents (odds ratios (OR) 20.37 to 28.51). Moderate to high anti-Leishmania seroprevalence was found throughout the eastern Adriatic coast and islands (4.0% to 22.2%) including the sites previously considered non-endemic. A highly endemic focus was identified in central coastal Dalmatia (seroprevalence 22.2%; OR: 1.72; 95% confidence interval (CI): 1.33-2.22). Regarding age, children aged 0-9 years were the most vulnerable group for asymptomatic Leishmania infection (OR: 2.19; 95% CI: 1.16-4.14).