First Evidence of Co-Circulation of Emerging Leishmania martiniquensis, Leishmania orientalis, and Crithidia sp. in Culicoides Biting Midges (Diptera: Ceratopogonidae), the Putative Vectors for Autochthonous Transmission in Southern Thailand

Abstract

Since 1996, autochthonous cases of emerging leishmaniasis caused by Leishmania (Mundinia) martiniquensis and Leishmania (Mundinia) orientalis have been more frequently reported, especially in the northern and southern parts of Thailand. However, the accurate identification of their natural vectors and reservoirs remains unconfirmed. Previous studies have suggested that these emerging parasites might be transmitted by other non-phlebotomine vectors. Herein, we speculated that Culicoides biting midges might act as the competent vectors responsible for autochthonous leishmaniasis in southern Thailand. In this research, 187 non-engorged, parous and gravid Culicoides females and 47 blood-engorged ones were trapped from the residences of two recently diagnosed visceral leishmaniasis patients in Sadao District and the unaffected site in Rattaphum District, Songkhla Province, southern Thailand. Species diversity and abundance of biting midges varied among the trapping sites. Using ITS1-PCR and BLASTn analysis, L. martiniquensis was predominantly detected in several Culicoides species, including C. peregrinus, C. oxystoma, C. mahasarakhamense, and C. huffi from the vicinity of patients’ houses; and in C. fordae and C. fulvus from the unaffected site. L. orientalis was also co-circulated in C. peregrinus and C. oxystoma caught near the second patient’s house. Additionally, Crithidia sp. were also detected using SSU rRNA-PCR across Culicoides spp. Host blood meal analysis of eight different Culicoides species from the unaffected site also revealed that all trapped Culicoides had fed on cows and goats, indicating the possible role of these mammalian species as reservoir hosts. Essentially, this study is the first entomological investigation, revealing the co-circulation of emerging trypanosomatids among several species of Culicoides biting midges and strongly supporting the potential role of this insect group as the main vectors responsible for the epidemiology of autochthonous leishmaniasis in southern Thailand.

Natural infection with Leishmania (Mundinia) martiniquensis supports Culicoides peregrinus (Diptera: Ceratopogonidae) as a potential vector of leishmaniasis and characterization of a Crithidia sp. isolated from the midges

“…BLAST analysis showed that among these, 19 sequences were similar to each other and to a Crithidia sp. reported from Thailand by Songumpai et al (2022) (GenBank accession number OP698037–OP698038) with 99.35–100% identity and to Cr. thermophila (GenBank accession number KY264937.1) with 97.00–97.74% identity.…”

“…was detected in Culicoides spp. in those areas ( Songumpai et al, 2022 ; Sunantaraporn et al, 2022 ).…”

Establishment of a mouse allergy model for Culicoides (Diptera: Ceratopogonidae)

“…Collected insects were immediately stored in liquid nitrogen and taken to the laboratory. Female Culicoides biting midges were identified and separated from other insects using a stereo microscope (SZ61, Olympus) according to morphological characteristics including antennae and wing patterns (Songumpai et al., 2022 ) and non‐engorged Culicoides were selected for subsequent whole‐body extract preparation.…”

Recent Advances in Chemotherapeutics for Leishmaniasis: Importance of the Cellular Biochemistry of the Parasite and Its Molecular Interaction with the Host

“…L. martiniquensis typically causes VL in humans and can be treated with amphotericin B as a first-line chemotherapeutic option. It has been reported that VL caused by L. martiniquensis has a higher relapse rate and occurs in individuals with HIV infection [ 8 , 9 ].…”