Identifying Cutaneous Leishmaniasis Vectors after an Outbreak: Anthropophily of Sergentomyia species and detection of Leishmania major DNA within Sergentomyia ingrami, in Ghana

Abstract

Abstract Prior to 1999, Ghana was not known to be a Cutaneous Leishmaniasis (CL) endemic country. The outbreak of CL in the Volta Region in 1999 resulted in the need for urgent investigations to understand the disease transmission dynamics. Monthly entomological collections from January 2006 to May 2007 revealed 99.8% (21,980/22,016) of sand flies collected were Sergentomyia and 0.2% (36/22,016) Phlebotomus, the putative vector of CL in the Old World. The density of Phlebotomus was so low, their vectorial role is uncertain. This study was therefore aimed at determining the possible vector species in the outbreak area. We collected sand flies from homes to examine anthropophily, by testing their blood meals. The blood-meal sources of 275 (20.5%) of 1342 collected female sand flies revealed the highest proportion of animal blood source was chicken (33.8%) and goat (12.4%). Humans accounted for 32% of blood meal sources. Identified species included: Sergentomyia africana africana (26.9%), S. ingrami (34.5%) and S. simillima (38.2%), which were found to have single and mixed blood-meals, with S. simillima having the highest proportion that contained human blood (14.6%). Using molecular methods, we examined unfed flies and flies found anthropophilic for the presence of Leishmania major DNA. Poolscreening analysis revealed 3 pools of S. ingrami positive with L. major DNA, with an infection rate of 1.27% (95% confidence interval: 2.467–3.647). This study showed that some Sergentomyia species are anthropophilic, contain L. major DNA, and could be involved in the transmission of CL in Ghana. There is however the need to conclusively validate the role of S. ingrami as a vector of L. major in Ghana, by isolating the parasite and initiating experimental transmission studies.