Sand Fly Fauna (Diptera: Psychodidae): Association Between Climatic Variables and Natural Leishmania Infection in Araçatuba, Brazil.

Visceral leishmaniasis (VL) is a zoonosis of major public health importance. In urban areas, Lutzomyia longipalpis is the primary vector of Leishmania (L.) infantum. This study assessed the seasonality, spatiotemporal distribution, and climatic factors associated with L. longipalpis abundance in Araçatuba, São Paulo State, and detected Leishmania spp. DNA in captured females. Monthly collections were conducted from March 2023 to February 2024 in 72 households across eight urban areas using CDC-type light traps placed indoors and in peridomestic environments. A total of 1641 specimens (1516 males and 125 females) were captured, with 92.4% originating from peridomestic areas. Area 3 had the highest density (n = 671) and was the only area with PCR-positive females (n = 3). Vector activity peaked in December 2023 (n = 335). Male abundance differed significantly among peridomestic areas, particularly between Areas 3, 5, 6, and 7. In peridomestic areas, higher final temperatures increased vector abundance, whereas higher initial temperatures and humidity reduced it. Indoors, final temperature, humidity, and month were significant predictors. L. longipalpis exhibited a defined seasonal and spatial pattern influenced by climatic conditions. The detection of PCR-positive females (Area 3) highlights the epidemiological role of the vector and underscores the need for targeted interventions to control VL.