Rift Valley fever in Nigeria: infections in domestic animals.

Abstract

Between 1986 and 1989, 2,255 sera collected from six domestic animal species in Nigeria were tested for antibodies to Rift Valley fever (RVF) virus. In addition, a longitudinal study was carried out from July 1987 to December 1988, using ten sentinel flocks on four farms at Ibadan and Ile-Ife, to determine the activity of RVF virus (RVFV). All samples were tested for haemagglutination-inhibiting antibodies and positive sera were further screened, using the plaque reduction neutralisation test. Of 2,255 samples, 259 (11.5%) had haemagglutination-inhibiting and neutralising antibodies, as follows: sheep (18.7%), goats (10.4%), cattle (10.2%), horses (9.8%) and camels (3.3%). The highest prevalence of RVFV antibody was found in the plateau area (18.4%). Animals aged three years or more had a higher prevalence of antibodies to RVFV. Longitudinal studies showed seroconversion to RVFV in ten of the 210 animals which were kept under observation (4.8%). All seroconversions occurred during the wet season. The results of this study indicate that the infection of animals with RVFV is widespread in Nigeria.