Cerebral malaria in children in the highlands of Kenya : Aspects of pathogenesis and clinical presentation

Abstract: Background: Malaria affects over 300 million persons in the world each year with a mortality of close to 2 million. In developing countries malaria has been endemic in the lowlands for centuries with no occurrence in the highlands above 2000 metres above sea level. This pattern has changed over the last decade whereby malaria is occurs in epidemics with a high morbidity and mortality among the inhabitants of the highlands especially children and pregnant women. Eldoret and its environs in Kenya is a highland area with an altitude of 2300 metres above sea level where malaria was rare up to the late 1980s. Since 1988 malaria occurs in epidemics in this region with a high prevalence of severe malaria especially cerebral malaria(CM). This led to the conduct of stndies that fonn the basis of this thesis with the aim of delineating aspects of pathogenesis and the clinical presentation of CM in the Western highlands of Kenya.Materials and Methods: Cross sectional, retrospective and prospective studies were conducted to study the prevalence of malaria among inpatients at the Moi Teaching and Referral Hospital (MTRH); to describe the clinical presentation of CM in the highlands; to compare temperatures in CM and uncomplicated malaria(UM) cases and to assay the serum tumour necrosis factor alpha (TNFa) and transforming growth factor beta (TGF-13)1 levels in these patients.A total of 4 720 children were retrospectively and prospectively studied over an 18 month period (1991-1993) to establish the top 20 diseases at the MTRH. This was followed by a prospective study of 23 CM and 12 UM cases in 1997. All the presenting features of the cases with CM were tabulated on admission and analysed so as to establish the clinical presentation of CM in this region and compare this to the standard as described by the World Health Organisation (WHO). A comparison was made between the brain, core and skin temperatures of the CM and UM cases with normal children acting as controls.This was a follow up of a similar stndy in 1993 that compared core and skin temperatures between measles, CM and UM with normal children as controls. Serum TNF-a and TGF-131 levels were assayed and compared among the CM and UM patients in the 1997 study and included the assay of cerebrospinal (CSF) TNF-α and TGF-β1 in CM.Results and conclusions: Malaria accounted for 3 3% of all admissions over the study period with a case fatality rate of 2.2% and a mortality rate of 10.7%. Most children with CM were aged 3-10 years and were of good nutritional status. They presented in coma, with fever, headache, convulsions and hyperparasitaemia and with a short duration of illness of less than 3 days. Severe anaemia and hypoglycaemia were not common features. Malaria is the leading cause of morbidity in the children stndied. CM in the highlands presents as that seen among non-immunes. There were no differences in brain, core and skin temperatures between the CM and UM patients. The brain temperature was however always lower than core temperature even in normal controls with brain temperature having a positive correlation with core temperature as the body temperature rises. Thus, the role of fever in the pathogenesis of CM is still unclear The serum TNF-α and TGF-β1 levels were the same in UM and CM cases with TNF-α and TGF-β1 having an inverse relationship to each other. Patients with deeper levels of coma had higher levels of TNF-α and lower levels of TGF-β1.