Molecular Evidence of Epizootic Haemorrhagic Disease Virus and Bluetongue Virus Circulation in Wild Ruminants in Namibia.

Abstract

Bluetongue virus (BTV) and epizootic haemorrhagic disease virus (EHDV) are Culicoides-borne orbiviruses affecting domestic and wild ruminants. Information on their circulation in Namibian wildlife is limited. This study investigated the molecular detection and serotype distribution of BTV and EHDV in wild ruminants from a commercial game farm in the Khomas Region, Namibia, where wildlife and livestock coexist. Between June and September 2019, spleen samples from 62 clinically healthy animals (kudu, oryx, and red hartebeest) were analysed by real-time RT-PCR using pan-BTV and pan-EHDV assays, followed by serotype-specific tests for selected BTV types. Two animals (3.23%) tested positive for EHDV. BTV RNA was detected in 24/62 animals (38.71%), with Ct values ranging from 28.3 to 38.4. BTV-3 and BTV-4 were the most frequently identified serotypes, while one sample was positive for BTV-1; six BTV-positive samples remained untyped. High Ct values and low RNA loads likely limited sequencing success. Although restricted to a single farm and a limited serotype panel, this study provides preliminary molecular evidence of BTV and EHDV circulation in Namibian wild ruminants, highlighting the need for broader epidemiological investigations at the wildlife-livestock interface.