The evolving transmission pattern of Rift Valley fever in the Arabian Peninsula.

Vector-borne viruses are no respecters of international boundaries. The recent outbreak of Rift Valley fever (RVF) in the Kingdom of Saudi Arabia (KSA) and Yemen in September 2000 clearly sends a message that once pathogens cross their known geographic limits, they tend to adapt to the local ecology in order to survive and maintain transmission. This paper examines the various factors that may contribute to the establishment of RVF in the Arabian Peninsula (AP) and its possible spread to other countries. The annual influx of over 2 million pilgrims for the Hajj (annual pilgrimage for Muslims) in the KSA, as well as the large migrant population in this region, generates high human and animal traffic that presents a challenging agenda for public health. The potential risks within this period as well as other peculiar ecological factors are discussed.