Rift Valley Fever--East Africa, 1997-1998.

In December 1997, the Kenya Ministry of Health and the World Health Organization (WHO) in Nairobi received reports of 478 unexplained deaths in the North Eastern province of Kenya and southern Somalia. Clinical features included acute onset of fever and headache associated with hemorrhage (hematochezia, hematemesis, and bleeding from other mucosal sites). Local health officials also reported high rates of illness and death resulting from hemorrhage among domestic animals in the area. This report describes the preliminary results of the outbreak investigation and the results of a serologic survey.