Molecular detection of bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) in captured Culicoides spp. in the northeastern regions of Mexico

Midges of Culicoides spp. (Diptera: Ceratopogonidae) captured in 2013 (February to November) in four micro-regions located in the northeast of Mexico were analyzed to determine the presence of genetic sequences of the viruses of Bluetongue (BT) and Epizootic Hemorrhagic Disease (EHD) by reverse transcription–polymerase chain reaction (RT-PCR). In all the micro-regions sampled, it was possible to detect the presence of culicoides biting midges, along with other insects. The basic phenological identification of midges showed that all specimens corresponded to the Culicoides variipennis complex (Wirth & Jones). The amount of captured midges was associated with the annual mean temperature, altitude and time of year at the site of capture (p <0.01). A total of 51 pools, each one of 3 to 15 female midges, were analyzed for genetic sequences for BTV (part of NS3 / NS3A gene segment 10) and EHDV (part of the NS1 gene segment 5) using oligonucleotides reported in previous studies. Except for the micro-region located in the municipality of Zaragoza, Nuevo Leon (23 ° 57'10.24''N, 99 ° 46'12.24''O; 1454 m), where it only was possible to capture one midge, midges groups captured at all other sites were RT-PCR positive for BTV and EHDV. The highest proportion of positive midges groups to RT-PCR was found in spring and summer. The presence of genetic sequences of BTV and EHDV in captured Culicoides spp. may eventually be associated with outbreaks of diseases caused by these viruses in wild and domestic ruminants in the northeastern part of Mexico. The information on the movement of midges carrying both viruses could be taken into account for the management of animal populations, and further studies are needed to confirm the presence of the mentioned viruses.