Merriam-Webster Collegiate Dictionary - rift valley fever

 noun  Etymology: (Great) Rift Valley, Africa  Date: circa 1931 an acute usually epizootic mosquito-borne disease of domestic animals chiefly of eastern and southern Africa that is caused by a single-stranded RNA virus (species Rift valley fever virus of the genus Phlebovirus, family Bunyaviridae), is marked especially by fever, abortion, and death of newborns, and is sometimes transmitted to humans usually in a less severe form