Aeta Tropica, 57(1994)289-300 289 © 1994 Elsevier Science B.V. All rights reserved 0001-706X/94/$07.00 ACTROP 00396 Severe childhood malaria in two areas of markedly different falciparum transmission in East Africa R.W. Snow a'b'*, I. Bastos de Azevedo ~, B.S. Lowe a'b'd, E.W. Kabiru a'e, C.G. NevilP 'g, S. Mwankusye c, G. Kassiga g, K. Marsh a'b, T. Teuscher c'* aKenya Medical Research Institute, Coastal Unit, P. O. Box 230, Kilifi, Kenya, bNuffield Department of Clinical Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK, CIfakara Centre of the National Institute for Medical Research, P. O. Box 53, Ifakara, Tanzania, aLiverpool School of Tropical Medicine, University of Liverpool, Liverpool, UK, ¢Division of Vector Borne Diseases, Ministry of Health, Nairobi, Kenya, rAfrican Medical and Research Foundation, Wilson Airport, Nairobi, Kenya, gSt Francis Designated District Hospital, Ifakara, Tanzania Received 25 January 1994; revision received and accepted 8 April 1994 Malaria remains a major public health challenge in sub-Saharan Africa, yet our knowledge of the epidemi- ology of malaria in terms of patterns of mortality and morbidity is limited. We have examined the presentation of severe, potentially life-threatening malaria to district hospitals in two very different trans- mission settings: Kilifi, Kenya with low seasonal transmission and Ifakara, Tanzania with high seasonal transmission. The minimum annual rates of severe disease in children below five years in both populations were similar (46 per 1000 children in Kilifi and 51 per 1000 children in Ifakara). However, there were important differences in the age and clinical patterns of severe disease; twice as many patients were under one year of age in Ifakara compared with Kilifi and there was a four fold higher rate of cerebral malaria and three fold lower rate of malaria anaemia among malaria patients at Kilifi compared with Ifakara. Reducing malaria transmission in Ifakara by 95%, for example with insecticide-treated bed nets, would result in a transmission setting comparable to that of Kilifi and although this reduction may yield early successes in reducing severe malaria morbidity and mortality in young, immunologically naive children, place these same children at increased risk at older ages of developing severe and potentially different manifestations of malaria infection hence producing no net cohort gain in survivorship from potentially fatal malaria. Key words: Severe malaria; Epidemiology; African children; Tanzania; Kenya Introduction Malaria still poses a major public health challenge in many parts of sub-Saharan Africa. An estimated half million African children die each year of malaria (Greenwood, 1990). Descriptions of the malaria problem and successes or failures in control have traditionally focused on rates of host infection and vector related features of transmission. This focus is incomplete when disease control rather than vector/parasite eradication are the accepted realistic goals. The epidemiology of *Corresponding authors. SSDI 0001-706X(94)00031-U