Phlebotomine Sand Flies in Southern Thailand: Entomological Survey, Identification of Blood Meals and Molecular Detection of Trypanosoma spp.

Simple Summary Phlebotomine sand flies (Diptera: Psychodidae) are hematophagous insects, and many species serve as vectors of various human and animal pathogens, including Leishmania and Trypanosoma protozoa. In Thailand, the first case of autochthonous leishmaniasis was reported 62 years ago. At present, the number of human cases is increasing in different regions of the country, but most cases are reported from southern Thailand. Therefore, we studied the potential transmission of Leishmania and Trypanosoma by sand flies in three provinces of southern Thailand, and analyzed blood sources of engorged sand fly females. We detected Trypanosoma sp. DNA in Sergentomyia barraudi, S. indica, S. khawi and Idiophlebotomus asperulus but no Leishmania spp. DNA. Moreover, bloodmeal analysis revealed that Trypanopsoma-positive females of S. barraudi and Sergentomyia sp. fed on dogs and humans, respectively. The results of this study contribute to the knowledge of leishmaniasis and trypanosomiasis presence and sand fly feeding behavior in southern Thailand. An entomological survey at rural and cavernicolous localities in four provinces in southern Thailand provided 155 blood-fed females of sand flies (Diptera: Psychodidae) that were identified based on morphological characters as Idiophlebotomus asperulus (n = 19), Phlebotomus stantoni (n = 4), P. argentipes (n = 3), Sergentomyia anodontis (n = 20), S. barraudi (n = 9), S. hamidi (n = 23), S. hodgsoni (n = 4), S. hodgsoni hodgsoni (n = 32), S. indica (n = 5), S. iyengari (n = 2), S. khawi (n = 17), S. silvatica (n = 11) and Sergentomyia sp. (n = 6). The dominant species in this study was S. hodgsoni hodgsoni, which was collected specifically in a Buddha cave. Screening for DNA of parasitic protozoans revealed eight specimens (5.16%) of four species (S. barraudi, S. indica, S. khawi and Id. asperulus) positive for Trypanosoma sp., while no Leishmania spp. DNA was detected. Blood meals of engorged females were identified by PCR-Restriction Fragment Length Polymorphism (PCR-RFLP) assay on a fragment of cytochrome b (cyt b) gene with a success rate 36%, humans, dogs, and rats being determined as sources of blood. Bloodmeal analysis of two Trypanopsoma-positive females (S. barraudi and Sergentomyia sp.) identified blood from dogs and humans, respectively. Our findings indicate that S. barraudi, S. indica, S. khawi and Id. asperulus may be incriminated in circulation of detected Trypanosoma spp.

Automated summary

This study investigates the potential transmission of Leishmania and Trypanosoma by sand flies in southern Thailand and analyzes the blood sources of engorged sand fly females. It was found that Trypanosoma DNA was present in certain species of sand flies, but no Leishmania DNA was detected. Blood meal analysis revealed that some sand flies fed on dogs and humans. The findings contribute to the understanding of leishmaniasis and trypanosomiasis presence and sand fly feeding behavior in southern Thailand.