Serological Evaluation of Cutaneous Leishmania tropica Infection in Northern Israel

Abstract

Leishmania spp. are medically important unicellular parasites transmitted by phlebotomine sand flies. The World Health Organization recently highlighted the importance of reliable diagnostic tools for leishmaniasis. Our study of human infection was conducted in two endemic foci of Leishmania tropica in the Galilee region, northern Israel. Elevated anti-Leishmania antibodies were present in the majority (78.6%) of L. tropica-PCR positive individuals. Moreover, the enzyme-linked immunosorbent assay showed high sensitivity, specificity, and negative and positive predictive values (ranging between 73% and 79%), thus fulfilling the basic requirement for future development of a serodiagnostic and screening tool. The anti-sand fly saliva antibodies used as biomarkers of exposure reflected the composition of the local sand fly fauna as well as the abundance of individual species. High levels of antibodies against vector salivary proteins may further indicate frequent exposure to sand flies and consequently a higher probability of Leishmania transmission.

Figure 1.

Human antibody response against Leishmania tropica and sand fly saliva. Human serum samples from Korazim and Tiberias, two Leishmania foci in northern Israel, and samples from the sand fly–free area, the Czech Republic (CZ), were screened for the presence of antibodies against (A) Leishmania tropica and against saliva of three sand fly species: (B) Phlebotomus arabicus, (C) Phlebotomus sergenti, and (D) Phlebotomus papatasi. Asterisks above y axes indicate significant differences (P < 0.05) between Leishmania-PCR–positive (open triangle) and Leishmania-PCR–negative (open circle) individuals from the same locality. Asterisks below y axes indicate significant differences (P < 0.05) between localities (regardless the Leishmania status). Samples were evaluated in triplicates and are presented as mean values.