Update: outbreak of Rift Valley fever -- Saudi Arabia August-November 2000.

Abstract

First cases of hemorrhagic fever affecting humans and animals confirmed as Rift Valley fever (RVF) were reported to the Ministry of Health (MOH) in Saudi Arabia in September 2000. This report provides updated information on the ongoing investigation conducted by the Saudi Arabian MOH. As of November 1 516 suspected case-patients with severe RVF were identified including 87 (17%) persons who have died. Of the 216 suspected case-patients tested 206 (95%) revealed either viral antigen or immunoglobulin M antibody. The median age of suspected case-patients was 46 years (range: 1-95 years); the majority were males Saudi citizens and came from the southwestern province of Jahan. The mean duration of onset to hospitalization was 3.3 days and average time elapsed from disease onset among 87 fatalities was 6.3 days. Moreover 125 (76%) of 165 case-patients reported close contact with animals and 91 (64%) of 143 reported a history of exposure to dead and/or aborted animals. Nearly all persons reported having had mosquito bites. Entomologic studies revealed two species of mosquitoes Culex tritaeniorrhynchus and Aedes caspius which have already been found to carry RVF virus. Further investigation suggests involvement of additional Aedes species. A correlation was found between areas where human cases were reported and the same flood irrigation farming identified by entomologists.