Sand fly gut microbiota in Leishmania transmission: roles, interactions, and paratransgenic prospects.

Leishmaniasis, a vector-borne disease caused by protozoa of the genus Leishmania, is transmitted by the bite of infected female Phlebotomine sand flies. Recent advances highlight the role of Phlebotominae gut microbiota in shaping vector competence and influencing Leishmania development. This review synthesises current knowledge on the diversity and dynamics of sand fly gut microbiota, its modulation by environmental factors and diet, and its interaction with Leishmania parasites. Special focus is placed on the immune and metabolic crosstalk between microbes and both the vector and host, including the role of bacterial components in modulating disease severity. The review also discusses the emerging potential of microbiota-based vector control strategies, particularly paratransgenesis using symbionts such as Wolbachia and Bacillus subtilis and outlines future directions for microbiota-based interventions in sand fly research.