Molecular screening of Leishmania and Wolbachia in sand fly populations from southwestern Iran

Leishmaniasis, a vector-borne disease, manifests in three primary clinical forms: cutaneous, visceral, and cutaneous-mucosal. The Gram-negative bacterium Wolbachia has been used as a biological control agent to combat various arthropod species. This research focuses on examining the prevalence of both Wolbachia and Leishmania infections in the endemic region of Elhayi City in southwestern Iran. Sand flies were collected during the spring and summer, both indoors and outdoors, in the study regions of Oshareh Kochak, Qalaeh Sahar, and Elhayi villages using sticky traps. After collection and identification, 100 female sand flies were chosen based on criteria including location, season, abdominal state, and species. DNA extraction was subsequently performed, and the polymerase chain reaction (PCR) method was applied to detect the presence of Leishmania and Wolbachia infections. Leishmania -positive samples identified and confirmed through PCR were further analyzed using the restriction fragment length polymorphism (RFLP) technique. 833 sand fly samples were collected, comprising 480 males and 353 females. Phlebotomus papatasi emerged as the dominant species in Elhayi City, representing 79.95% of the specimens. Among the female sand flies, the abdominal condition was categorized as follows: 22.66% blood-fed, 19.26% gravid, 7.93% semi-gravid, and 50.15% unfed. Regional variations in Leishmania infection rates were observed, with no infections detected in Elhayi village, 7.31% in Oshareh Kochak, and 17.64% in Qalaeh Sahar. All infected samples were positive for L. major , with co-infections of L. major and L. turanica identified in two separate specimens (one Ph. alexandri and one Ph. papatasi ). Wolbachia infections were only observed in Ph. papatasi , with infection rates of 7.14%, 5.40%, and 42.85% in Oshareh Kochak, Qalaeh Sahar, and Elhayi villages, respectively. Notably, no co-infection involving both Wolbachia and Leishmania parasites was detected. In this study, a Leishmania infection rate of 12% and a Wolbachia infection rate of 7% were identified in Ph. papatasi , the primary vector of zoonotic cutaneous leishmaniasis in Elhayi City. Not applicable.