The disease is caused by the RVF virus, generally found in regions of eastern and southern Africa, but also in most countries of sub-Saharan Africa, Madagascar, Saudi Arabia and Yemen.
Haigust põhjustab RVF-viirus, mida esineb tavaliselt Ida- ja Lõuna-Aafrikas, ent ka enamikus Sahara-taguse Aafrika riikides, Madagaskaril, Saudi Araabias ja Jeemenis.