Molecular Identification of Host Blood Meals and Detection of Blood Parasites in Culicoides Latreille (Diptera: Ceratopogonidae) Collected from Phatthalung Province, Southern Thailand

Simple Summary Biting midges, which feed on a variety of hosts, transmit a wide range of harmful human and animal viruses and parasites. According to recent studies in Thailand, biting midges may act as potential vectors for leishmaniasis and trypanosomiasis. The purpose of this study is to look for Leishmania and Trypanosoma DNA in biting midges obtained in the field in a leishmaniasis-endemic area in Phatthalung province, Southern Thailand. In addition, we analysed engorged midges for host blood DNA and screened the collected midges for avian haemosporidian parasites. According to our findings, biting midges have a diversified feeding habit and may be able to transmit various pathogens, including trypanosomatid and avian haemosporidian parasites. Five hundred and fifty-nine female biting midges were collected, and seventeen species in six subgenera (Avaritia, Haemophoructus, Hoffmania, Meijerehelea, Remmia, and Trithecoides) and two groups (Clavipalpis and Shortti) were identified. The dominant Culicoides species was C. peregrinus (30.94%), followed by C. subgenus Trithecoides. From blood meal analysis of engorged biting midges, they were found to feed on cows, dogs, pigs, and avians. The majority of blood preferences of biting midges (68%; 49/72) displayed a mixed pattern of host blood DNA (cow and avian). The overall non-engorged biting midge field infectivity rate was 1.44 % (7/487). We detected Leucocytozoon sp. in three Culicoides specimens, one from each species: C. fulvus, C. oxystoma, and C. subgenus Trithecoides. Crithidia sp. was found in two C. peregrinus specimens, and Trypanosoma sp. and P. juxtanucleare were separately found in two C. guttifer. More consideration should be paid to the capacity of biting midges to transmit pathogens such as avian haemosporidian and trypanosomatid parasites. To demonstrate that these biting midges are natural vectors of trypanosomatid parasites, additional research must be conducted with a greater number of biting midges in other endemic regions.

Automated summary

Biting midges, as small insects that feed on various hosts, have been found to potentially carry harmful pathogens such as Leishmania and Trypanosoma. This study collected biting midges in a leishmaniasis-endemic area in Thailand and found that they had a diversified feeding habit, feeding on cows, dogs, pigs, and avians. The study also detected the presence of avian haemosporidian parasites in the collected midges. Further research is needed to determine if these biting midges can act as natural vectors for trypanosomatid parasites.