CULICOIDES IN RELATION TO TRANSMISSION OF AFRICAN HORSE SICKNESS VIRUS IN THE GAMBIA

Twelve light trap collections made near overnight shelters of horses a nd donkeys in four villages in the Central River Division of The Gambi a captured fourteen species of biting midge of the genus Culicoides. F ive species new to The Gambia were identified. This brought the number of recognized species of Culicoides (after a revision of C. schultzei ) to twenty-nine in The Gambia. Species known or suspected as vectors of African horse sickness virus (AHSV) and bluetongue virus (BTV) comp rised 83% of female captures, 65% of captures being C. imicola or its sibling species, C. miombo. Captures of female Culicoides in the late dry season were almost as large as in the early dry season, despite th e extreme heat and dryness at this time of the year. Tests on batches of formalin-preserved female midges, using AHSV or BTV antigen capture ELISAs, did not show the presence of any virus amongst 2286 females i n 240 aliquots. Nearly all Gambian equines are reportedly seropositive to AHSV and these results suggest that virus challenge from Culicoide s vectors may be a factor in the health of Gambian horses and donkeys.