Investigation of Leishmania infantum Infection and Feeding Preferences of Lutzomyia longipalpis During Deltamethrin (4%) Dog Collar Intervention

Leishmaniasis is a zoonotic disease caused by protozoa of the genus Leishmania, transmitted by phlebotomine sand flies. Understanding the feeding behavior and infection rates of these vectors is crucial for disease surveillance and control. We aimed to investigate the natural infection rate of Leishmania spp. in phlebotomines and analyze their blood-feeding patterns in one of the priority areas of the state of São Paulo for the implementation of insecticide-impregnated dog collars. Sand flies were collected from urban and peri-urban areas between 2022 and 2024 using CDC light traps, manual aspiration, and Shannon traps. PCR was used to detect Leishmania DNA (SSU rDNA gene), and blood meal sources (COI gene). A total of 414 sand flies were collected, with 222 engorged females analyzed for blood meals and 192 specimens tested for Leishmania spp. infection. The predominant blood source was humans (67%), followed by chickens (64.1%), and dogs (18.9%), considering that 45.1% of the samples presented mixed blood meals. Leishmania infantum was found in 1% of the samples. These findings highlight the feeding plasticity of sand flies and their potential role in disease transmission, reinforcing the need for continuous epidemiological surveillance and vector control strategies, particularly the implementation of insecticide-impregnated dog collars.