| Abstract: | Recently, Rift Valley fever virus (RVFV) disease has assumed public health significance as associated with human fatalities on a significant scale both in the North, Central and South of Africa. In West Africa, little information is available about RVFV disease. However, in Nigeria, four strains of the virus have been isolated from sheep, culicoides, and mosquitoes; also, RVFV antibodies were demonstrated in some domestic animal sera. The West African dwarf sheep, which is indigenous to Nigeria, is highly suspectible to experimental RVFV infection. No information is available about RVFV disease in man. Human blood and serum samples collected from different parts of Nigeria were examined for RVFV and its specific antibodies using mouse inoculation technique, complement fixation (CF), and neutralization (N) tests. In addition, a limited number of hospital records of suspected RVFV cases were examined. No RVFV was isolated from 19,026 samples examined for virus content. Of the 2,223 sera tested, 146 or 6.6% were positive for RVFV antibodies by the CF test. There was a good correlation between the CF and N tests, in RVFV serodiagnosis. One hundred forty-four of the 146 CF-positive sera were positive in N tests; in addition, all of the 50 CF-negative sera were negative in N tests for RVFV antibodies. From the limited hospital records examined, it appears that RVFV infection in Nigeria presents as an influenza-like illness. On one occasion, there was ocular complication following a febrile illness, associated with the development of specific RVFV antibodies. With less than 10% of the surveyed population immune to RVFV, the potentials for a severe eqizootic of RVFV disease in Nigeria appear great. Further studies on such factors as climate and vector population, as well as the reservoir and host range of RVFV, are in progress. |
