Epidemic of malaria in north-eastern Kenya

A major epidemic of Plasmodium falciparum malaria occurred in a nonimmune population in northeastern Kenya during January-May 1998. The epidemic was preceded by drought in 1996 and most of 1997, then by major rainfall and floods in the last 2 months of 1997. A two-stage cluster-sampling survey conducted at mobile clinics in Wajir, Kenya, in 1988, retrospectively assessed malaria prevalence and mortality. From February 14 to May 3, 1998, a total of 23,377 malaria cases (attack rate, 38.9%) were reported. Average daily crude mortality was 9.4/10,000 and daily under-5 mortality was 28.4/10,000. The most common drugs administered to patients presenting to mobile units were chloroquine and pyrimethamine. The positive predictive values of clinical signs of malaria in relation to parasitemia stage were higher among patients with temperatures above 37.5 degrees Celsius (65%) or splenomegaly (46%). 380 cases of severe malaria were admitted to the malaria treatment unit for a mean stay of 2.3 days; 31 of these patients died (case fatality ratio, 8.2%). The epidemic's severity was aggravated by late recognition and a lack of preparedness.