Review

Age patterns of severe paediatric malaria and their relationship to Plasmodium falciparum transmission intensity

Emelda A Okiro¹ , Abdullah Al-Taiar² , Hugh Reyburn^3,4 , Richard Idro^5,6 , James A Berkley^6,7 and Robert W Snow^1,7

¹  Malaria Public Health and Epidemiology Group, Centre for Geographic Medicine, KEMRI-Wellcome Trust Collaborative Programme, Kenyatta National Hospital Grounds P.O. Box 43640-00100, Nairobi, Kenya

²  Faculty of Medicine and Health Sciences, Sana'a University, P.O. Box 13078, Sana'a, Yemen

³  London School of Hygiene and Tropical Medicine, Keppel St, London, WC1E 7HT, UK

⁴  Kilimanjaro Christian Medical Centre P.O. Box 2228 Moshi, Tanzania

⁵  Department of Paediatrics, Mulago Hospital/Makerere University Medical School Kampala, Uganda

⁶  Kenya Medical Research Institute, Centre for Geographic Medicine Research – Coast, Kilifi, Kenya P.O. Box 230-80108, Kilifi, Kenya

⁷  Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, CCVTM, Oxford, OX3 9DS, UK

author email corresponding author email

Malaria Journal 2009, 8:4doi:10.1186/1475-2875-8-4

Published:	7 January 2009

Abstract

Background

The understanding of the epidemiology of severe malaria in African children remains incomplete across the spectrum of Plasmodium falciparum transmission intensities through which communities might expect to transition, as intervention coverage expands.

Methods

Paediatric admission data were assembled from 13 hospitals serving 17 communities between 1990 and 2007. Estimates of Plasmodium falciparum transmission intensity in these communities were assembled to be spatially and temporally congruent to the clinical admission data. The analysis focused on the relationships between community derived parasite prevalence and the age and clinical presentation of paediatric malaria in children aged 0–9 years admitted to hospital.

Results

As transmission intensity declined a greater proportion of malaria admissions were in older children. There was a strong linear relationship between increasing transmission intensity and the proportion of paediatric malaria admissions that were infants (R² = 0.73, p < 0.001). Cerebral malaria was reported among 4% and severe malaria anaemia among 17% of all malaria admissions. At higher transmission intensity cerebral malaria was a less common presentation compared to lower transmission sites. There was no obvious relationship between the proportions of children with severe malaria anaemia and transmission intensity.

Conclusion

As the intensity of malaria transmission declines in Africa through the scaling up of insecticide-treated nets and other vector control measures a focus of disease prevention among very young children becomes less appropriate. The understanding of the relationship between parasite exposure and patterns of disease risk should be used to adapt malaria control strategies in different epidemiological settings.