A regional survey for RVF antibody prevalence in domestic ungulates, primarily goats and sheep, was conducted in Jazan and Asir provinces. RVF antibodies also were found among ungulates in other surveyed areas. A correlation was found between areas where human cases were reported and the same flood irrigation farming areas in the upper reaches of the wadis identified by the entomologists. World Health Organization, Geneva, Switzerland. P Jupp, PhD, A Kemp, MS, F Burt, PhD, R Swanepoel, PhD, Special Pathogens Unit, National Institute of Virology, Johannesburg, South Africa.
Most human infection is associated with an uncomplicated febrile illness or is inapparent.
More severe complications include retinitis, hepatitis, renal failure, hemorrhagic fever, encephalitis, and death. This outbreak extends the geographic distribution of known infection outside of Africa and indicates this virus may be able to establish itself almost anywhere in the world based on the availability of potential permissive vectors and animal reservoirs. Official reports from Yemen suggest ongoing transmission over a large area, compared with the outbreak in Saudi Arabia, which is more circumscribed and is now mainly focused in Asir province. However, the differing case definitions and surveillance methodologies preclude a direct comparison of the Saudi Arabian and Yemeni outbreaks. Nevertheless, these outbreaks demonstrate disease transmission in an approximately 600 km area, including the flood plains of the wadis extending from the Sarawat mountains to the Red Sea coastal plain and extending from the Hodediah governate in Yemen to the Al Quendafah health region in Saudi Arabia.