A serological survey of Rift Valley fever antibodies in the northern Sinai

In the aftermath of an extensive Egyptian Rift Valley fever (RVF) epidemic during 1977–1978, RVF activity in the adjacent Sinai peninsula has been inferred from the presence of haemagglutination-inhibition (HI) antibiodies in sera from indigenous humans and rodents. We attempted to confirm these findings by HI testing of sera from Israeli soldiers serving in the region of the El Arish Wadi system in the Sinai, and from indigenous rodents. Six of 199 human sera (3.0%) and two of 88 rodent sera (2.3%) were positive, but none reacted in the more specific plaque-reduction neutralization test. We conclude that there is no definitive serological evidence for RVF activity in the Sinai and that sera reacting in the HI test must be confirmed by a more specific serological procedure.