WESSELSBRON VIRUS-ANTIBODY IN DOMESTIC-ANIMALS IN NIGERIA - RETROSPECTIVE AND PROSPECTIVE STUDIES

Retrospective and prospective serological surveys to determine the pre valence of Wesslsbron (WSL) virus infections in animal populations wer e carried out in different vegetational zones in Nigeria. Sera from 1, 492 animals comprising 292 camels, 81 horses, 4 donkeys, 320 cattle, 2 35 sheep, 260 goats, 114 pigs, 101 dogs and 85 domestic fowls were ass ayed by haemagglutination-inhibition (HI) test for presence of antibod ies to WSL virus and other flavivirus antigens: Yellow Fever (YF), Pot iskum (POT), Banzi (BAN), Uganda S (UGS) and West Nile (WN) viruses. F our hundred and eighty one (32%) of the total sera tested were positiv e for the presence of flavivirus antibodies. The prevalence rates amon g animals varied with species and vegetational zones of the country. T he highest prevalence was noted in animals from a swamp forest zone an d was higher among camels, horses, donkeys and sheep when compared wit h goats, pigs and fowls in different zones. Although monotypic reactio ns with WSL virus antigen were observed in positive sera, the majority of the WSL virus positive sera cross-reacted with more than two other flavivirus antigens. Serological corss-reactions were most extensive in WSL virus positive horse sera. A ten month sentinel survey among 28 cattle, 68 sheep and 30 goats revealed considerable activity of WSL v irus in Nigeria. Of these, 11 cattle and 12 sheep showed antibody conv ersion to WSL virus antigen. None of the goats seroconverted. Although , there are no records of outbreak of WSL disease in Nigeria, this stu dy revealed that WSL virus is actively circulating among livestock pop ulations in this environment. Flavivirus nucleotide data are needed fo r final determination of genetic relatedness in this group of viruses.