Culicoides Latreille (Diptera: Ceratopogonidae) as potential vectors for Leishmania martiniquensis and Trypanosoma sp. in northern Thailand.

Sakone Sunantaraporn,Sriwatapron Sor-Suwan,Arunrat Thepparat,Padet Siriyasatien,Atchara Phumee,Glenn Bellis,Rungfar Boonserm,Mathieu Nacher

doi:10.1371/journal.pntd.0010014

Abstract

Biting midges of genus Culicoides (Diptera: Ceratopogonidae) are the vectors of several pathogenic arboviruses and parasites of humans and animals. Several reports have suggested that biting midges might be a potential vector of Leishmania parasites. In this study, we screened for Leishmania and Trypanosoma DNA in biting midges collected from near the home of a leishmaniasis patient in Lamphun province, northern Thailand by using UV-CDC light traps. The identification of biting midge species was based on morphological characters and confirmed using the Cytochrome C oxidase subunit I (COI) gene. The detection of Leishmania and Trypanosoma DNA was performed by amplifying the internal transcribed spacer 1 (ITS1) and small subunit ribosomal RNA (SSU rRNA) genes, respectively. All the amplified PCR amplicons were cloned and sequenced. The collected 223 biting midges belonged to seven species (Culicoides mahasarakhamense, C. guttifer, C. innoxius, C. sumatrae, C. huffi, C. oxystoma, and C. palpifer). The dominant species found in this study was C. mahasarakhamense (47.53%). Leishmania martiniquensis DNA was detected in three samples of 106 specimens of C. mahasarakhamense tested indicating a field infection rate of 2.83%, which is comparable to reported rates in local phlebotomines. Moreover, we also detected Trypanosoma sp. DNA in one sample of C. huffi. To our knowledge, this is the first molecular detection of L. martiniquensis in C. mahasarakhamense as well as the first detection of avian Trypanosoma in C. huffi. Blood meal analysis of engorged specimens of C. mahasarakhamense, C. guttifer, and C. huffi revealed that all specimens had fed on avian, however, further studies of the host ranges of Culicoides are needed to gain a better insight of potential vectors of emerging leishmaniasis. Clarification of the vectors of these parasites is also important to provide tools to establish effective disease prevention and control programs in Thailand.

Highlights

Culicoides Latreille are minute hematophagous insects belonging to the family Ceratopogonidae [1]
Our studies demonstrated the first detection of L. martiniquensis in Culicoides mahasarakhamense and Trypanosoma sp., which is closely related to avian Trypanosome in C. huffi from an endemic area of leishmaniasis in northern Thailand
This study aims to assess the vector potential of Culicoides for Leishmania and Trypanosoma parasites in an endemic area in northern Thailand

Summary

Introduction

Culicoides Latreille are minute hematophagous insects belonging to the family Ceratopogonidae [1]. Leishmaniasis is a vector-borne disease that is caused by flagellated protozoa of the genus Leishmania. In Thailand, leishmaniasis is an emerging disease with the first autochthonous visceral leishmaniasis (VL) cases being reported in southern regions in 1996 [14]. The causative agents of autochthonous leishmaniasis in Thailand are Leishmania martiniquensis Desbois, Pratlong & Dedet 2014 [15,16] and L. orientalis Bate & Jariyapan 2018 (previously reported as "L. siamensis"), which both belong to L. subgenus Mundinia [17]. The disease has been reported in both immunocompetent and immunocompromised patients, especially in patients infected with human immunodeficiency virus (HIV) and is endemic in the southern, and the northern regions of the country [18]

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