Investigating potential sand fly vectors after the first reported outbreak of cutaneous leishmaniasis in Ghana

Abstract

Background: Leishmaniasis is a parasitic disease caused by species of the genus Leishmania, which are transmitted through the bite of infected female sand flies. Since the first reported outbreak of cutaneous leishmaniasis in Ghana, in 1999, there has been limited published information on its vectors and reservoir hosts there. Previous studies have shown strong dominance of the sand fly genus Sergentomyia over the genus Phlebotomus in Ghana. Thus the aim of this study was to determine the possible sand fly vector species in Ghana, as well as their human-feeding behavior, from the time of the first reported outbreak of CL in the country.

Methods: Sand flies were collected from randomly selected houses in three communities. They were identified and used for blood meal source identification and the detection of Leishmania infection using molecular methods. RESULTS: A total of 1051 female sand flies were morphologically identified, of which Sergentomyia africana africana (29%) was the predominant species. Among the 275 female sand flies that had blood-fed, the identified blood meal sources included chicken (33.8%) and goat (12.4%); the percentage of human blood meals was 32%. Single-source and mixed-source blood meals were identified in Sergentomyia africana africana (11.6%), Sergentomyia ingrami (14.9%) and Sergentomyia simillima (20%), with S. simillima having the highest proportion of blood meals that included human blood (14.6%). Using molecular methods, unfed sand flies and identified human-feeding species were examined for the presence of Leishmania DNA. Pool screening analysis revealed three pools of S. ingrami positive for Leishmania major DNA, with an infection rate of 1.27% (95% confidence interval 2.467-3.647).

Conclusions: The findings suggest that some Sergentomyia species may be involved in the transmission of cutaneous leishmaniasis in Ghana. However, the role of S. ingrami as a vector of leishmaniasis in Ghana needs to be conclusively validated by isolating the parasite from this species and through experimental transmission studies.

Keywords: Cutaneous leishmaniasis; Ghana; Neglected tropical disease; Phlebotomus; Sergentomyia.

Fig. 1

Variation in the human blood index among the collected sand fly species

Fig. 2

a Detection of Leishmania DNA in Sergentomyia ingrami pools using internal transcribed spacer region 1-polymerase chain reaction. M 100-base pair marker, lane 1 positive control with 5 µg DNA from Leishmania tropica, lane 2 positive control with 5 µg DNA from Leishmania major, lane 3 amplified Leishmania DNA within the human blood-fed S. ingrami pool, lanes 4 and 5 amplified Leishmania DNA within unfed S. ingrami pools, lane 6 negative control. b Polymerase chain reaction-restriction fragment length polymorphism analysis of internal transcribed spacer region 1 genes obtained with HaeIII. M 100-base pair marker, lane 1 L. tropica reference strain, lane 2 L. major reference strain, lanes 3–5 S. ingrami pools