Molecular Identification of Culicoides Species and Host Preference Blood Meal in the African Horse Sickness Outbreak-Affected Area in Hua Hin District, Prachuap Khiri Khan Province, Thailand

Abstract

African horse sickness (AHS) was reported as an outbreak in Thailand in 2020. Hematophagous insects from the genus Culicoides are the suspected vector responsible for AHS transmission. Horses in Hua Hin district, Prachuab Khiri Khan province, Thailand, were affected and died from AHS in 2020. However, the potential Culicoides species and its host preference blood meal in the affected areas are unknown. To investigate the potential vectors of AHS, Culicoides were collected using ultraviolet light traps placed near horse stables. Six horse farms, including five farms with AHS history and one farm without AHS history, were included in this study. Morphological and molecular identification of the Culicoides species was performed. Polymerase chain reaction (PCR) targeting the cytochrome b oxidase I (COXI) gene for confirmation of the Culicoides species, identification of the prepronociceptin (PNOC) gene for host preference blood meal, and bidirectional sequencing were conducted. Consequently, 1008 female Culicoides were collected, consisting of 708 and 300 samples captured at positions A and B at a distance of <2 and >5 m from the horse, respectively. Twelve Culicoides species identified by morphology were noted, including C. oxystoma (71.92%), C. imicola (20.44%), C. actoni (2.28%), C. flavipunctatus (1.98%), C. asiana (0.99%), C. peregrinus (0.60%), C. huffi (0.60%), C. brevitarsis (0.40%), C. innoxius (0.30%), C. histrio (0.30%), C. minimus (0.10%), and C. geminus (0.10%). The PCR detection of the Culicoides COXI gene confirmed Culicoides species in 23 DNA samples. PCR targeting the PNOC gene revealed that the Culicoides collected in this study fed on Equus caballus (86.25%), Canis lupus familiaris (6.25%), Sus scrofa (3.75%), and Homo sapiens (3.75%) for their blood meal. Human blood was identified from two samples of C. oxystoma and a sample of C. imicola. Three dominant species including C. oxystoma, C. imicola, and C. actoni that were reported in the Hua Hin area prefer to feed on horse blood. Moreover, C. oxystoma, C. imicola, and C. bravatarsis also feed on canine blood. This study revealed the species of Culicoides in Hua Hin district, Thailand, after the AHS outbreak.

Diversity, Abundance and Host Blood Meal Analysis of Culicoides Latreille (Diptera: Ceratopogonidae) from Cattle Pens in Different Land Use Types from Thailand

“…Information on the host blood meal is important in the determination of the vectorial capacity and disease epidemiology of hematophagous insect species [45,46]. In Thailand, host blood meal sources have been reported for 21 biting midge species based on molecular identification [7,10,36,47]. In this study, we report additional host blood sources for 16 species in Thailand.…”

Environmental and Historical Determinants of African Horse Sickness: Insights from Predictive Modeling

“…Rising temperatures are expanding the habitats of AHSV vectors, notably C. imicola, leading to a northward spread and enhanced AHSV transmission (1,12,28,59,60). This change, coupled with the identification of new vector species, suggests an increased risk of AHS in broader areas (61,62). Recent outbreaks of Bluetongue virus, transmitted by the same vectors, further highlight the growing concern about AHSV expansion (63,64).…”

Nanopore-Based Surveillance of Leishmania Parasites in Culicoides Latrielle (Diptera: Ceratopogonidae) Caught from the Affected Community and Tham Phra Cave in Chiang Rai Province, the Endemic Area of Leishmaniasis in Northern Thailand

“…Apart from C. mahasarakhamense, which has formerly been reported as a putative leishmaniasis vector [31], our study represents the first molecular evidence of Leishmania in C. guttifer, C. (Trithecoides) spp., C. jacobsoni, C. oxystoma, and C. orientalis in Northern Thailand. However, these suspected vectors have been known to be livestock-associated species that mainly feed on peridomestic animals [48,[52][53][54][55][56]. This implies that autochthonous Leishmania parasites circulate in animal reservoirs, and the most likely mode of transmis-sion is therefore zoonotic rather than anthroponotic.…”

“…Unfortunately, no blood-engorged specimens were present in our midge collection. To our knowledge, only three Culicoides species in Thailand-namely C. brevitarsis [48], C. imicola [54], and C. oxystoma [54]-have thus far been recorded for their opportunistic behavior of human feeding, implicating them for potential participation in pathogen transmission to humans. Therefore, host preference analysis of blood-engorged specimens, particularly of prevalent midge species, from leishmaniasis-affected sites is further required to determine which vector species is mainly responsible for the transmission of human leishmaniasis in our investigation area.…”