Isolation of bluetongue and related viruses from Culicoides spp. in the Sudan

Infection of domestic ruminants with bluetongue virus (BTV) is widespread in the Sudan but there are no records of vector species of Culicoides in that country. Therefore, light-trap collections of Culicoides for virus isolation procedures were made in the Khartoum and Um Benein areas of the Sudan during September-October 1982. Two virus isolates were made from pools of unengorged, female Culicoides. An isolate from a pool of C. kingi (schultzei gp) is a member of the Epizootic Haemorrhagic Disease (EHD) serogroup. The other isolate from a pool of C. imicola, a known BTV vector in other parts of Africa, is type-5 BTV. In laboratory experiments, the North American vector of BTV, C. variipennis, supported replication of both Sudanese isolates to a high titre and transmission occurred after 10 days' incubation. This paper records the first isolation in the Sudan of arboviruses from Culicoides, with the identification of a BTV serotype and the presence of a member of the EHD (genus orbivirus, family Reoviridae) serogroup.