Seasonality and Prevalence of Leishmania major Infection in Phlebotomus duboscqi Neveu-Lemaire from Two Neighboring Villages in Central Mali

Abstract

Phlebotomus duboscqi is the principle vector of Leishmania major, the causative agent of cutaneous leishmaniasis (CL), in West Africa and is the suspected vector in Mali. Although found throughout the country the seasonality and infection prevalence of P. duboscqi has not been established in Mali. We conducted a three year study in two neighboring villages, Kemena and Sougoula, in Central Mali, an area with a leishmanin skin test positivity of up to 45%. During the first year, we evaluated the overall diversity of sand flies. Of 18,595 flies collected, 12,952 (69%) belonged to 12 species of Sergentomyia and 5,643 (31%) to two species of the genus Phlebotomus, P. duboscqi and P. rodhaini. Of those, P. duboscqi was the most abundant, representing 99% of the collected Phlebotomus species. P. duboscqi was the primary sand fly collected inside dwellings, mostly by resting site collection. The seasonality and infection prevalence of P. duboscqi was monitored over two consecutive years. P. dubsocqi were collected throughout the year. Using a quasi-Poisson model we observed a significant annual (year 1 to year 2), seasonal (monthly) and village effect (Kemena versus Sougoula) on the number of collected P. duboscqi. The significant seasonal effect of the quasi-Poisson model reflects two seasonal collection peaks in May-July and October-November. The infection status of pooled P. duboscqi females was determined by PCR. The infection prevalence of pooled females, estimated using the maximum likelihood estimate of prevalence, was 2.7% in Kemena and Sougoula. Based on the PCR product size, L. major was identified as the only species found in flies from the two villages. This was confirmed by sequence alignment of a subset of PCR products from infected flies to known Leishmania species, incriminating P. duboscqi as the vector of CL in Mali.

Diversity of Sand Flies (Diptera: Psychodidae: Phlebotominae) in Two Different Eco-Climatic and Endemic Zones of Cutaneous Leishmaniasis in Mali, West Africa

“…Except for Sergentomyia fallax that was observed in Tieneguebougou and not in Boundioba, there was no difference in sand flies species diversity between the two eco-climatic zones. Species of the genus Sergentomyia were the most frequent in both villages, in line with the observation made in Central Mali, an endemic area of CL (Anderson et al 2011) by previous studies.…”

“…All of them have been already observed in previous studies in Mali (Anderson et al 2011, Berdjane-Brouk et al 2012) except for Se. madagscariensis, Se.…”

“…rodhaini could be a secondary vector in addition to Ph. duboscqi that has already been incriminated by previous studies in CL transmission in Mali (Anderson et al 2011).…”

“…duboscqi and Ph. rodhaini, incriminated in the transmission of Leishmania major in West Africa (Anderson et al 2011), were collected during this study. Phlebotomus duboscqi was observed in both sites, while Ph.…”

“…Previous entomological studies have revealed the presence of 14 species of sand flies in Baroueli (Segou region), 20 species in Bandiagara (Mopti Region), and 13 species in the surroundings of Bamako (Anderson et al 2011, Demba-Kodindo et al 2014, among which only Phlebotomus duboscqi Neveu-Lemaire was recognized as a major vector of CL (Anderson et al 2011). Phlebotomus duboscqi was captured for the first time in Hombori, Mopti region (Desjeux et al 1981).…”