Phlebotomine sand fly distribution, abundance and pathogen associations in Thailand: a scoping review

Abstract

Phlebotomine sand flies are found across multiple regions of Thailand, with growing recognitionof their role in transmitting zoonotic pathogens. Environmental factors, including climatevariability and vector ecology, may influence their distribution and activity, contributing to thepotential spread of zoonotic pathogens in Southeast Asia. However, comprehensive data on sandfly distribution in Thailand remain limited. To address this gap, a systematic review wasconducted following PRISMA guidelines. Out of 112 records retrieved, 33 met the inclusioncriteria and quality assessment for further analysis. As per results, sand flies are widespread inThailand, with a high level of species diversity comprising 42 species of 6 different genera.However, several provinces lack data on the presence and distribution of sandflies. Elevenspecies were identified as the overall abundant species throughout the studies from January 2007to June 2025 and grouped by abundance: low-abundance species (Sergentomyia barguesae,Sergentomyia phadangensis, Sergentomyia barraudi, Sergentomyia indica), abundant butunderstudied species (Sergentomyia sylvatica, Sergentomyia anodontis, Neopulpusvietnamensis), and most abundant species (Sergentomyia hodgsoni, Sergentomyia gemmea,Sergentomyia iyengari, and Sergentomyia khawi). From the most abundant species, S. khawitested positive for several pathogens, such as Leishmania spp., Trypanosoma spp., Bartonellaspp. and orbivirus. Besides, S. khawi has been shown to exhibit human-biting behavior throughthe analysis of blood meal. These findings raise concerns about its potential role in pathogentransmission, especially concerning zoonotic pathogens. However, vector competence remainsunproven for some of these pathogens, suggesting the need for further research.