Reducing children’s exposure to malaria infection in Africa substantially cuts the risk of hospitalisation for emergency care

Researchers from the KEMRI-Wellcome Trust Research Programme and University of Oxford have worked with colleagues across East Africa to understand the risks of children under 10 years developing severe malaria. The authors linked emergency pediatric hospital admissions to 35 locations where the chances of childhood infection varied from very low to very high.

The Wellcome-funded study, published in Science, represents the first quantitative analysis of the relationship between community infection risks and admission rates with malaria for over 25 years.

“Across Africa tens of thousands of children are admitted to hospital with severe malaria posing a heavy burden on the health system”, says Dr Alice Kamau from the Kenya Medical Research Institute-Wellcome collaboration in Kenya, and co-first author. “Our findings support continued efforts across Africa to reduce infection risks in children under five years of age”.

The study shows that severe malaria admissions were rare when transmission was low but rose rapidly with increased infection rates; each 25% increase in community prevalence was found to double the rate of children needing emergency care.

“Quantifying the relationship between infection risk and severe disease outcomes allows us to better formulate intervention policies that are targeted in the right areas, protect the most vulnerable age groups and maximize limited resources”, says Dr Rob Paton, from the University of Oxford, co-first author.

In areas of higher infection risk, the burden of admissions was concentrated in children under two, highlighting the impact of naturally acquired immunity to severe, life-threatening disease. In areas of lower transmission risk, admitted children tended to be older but this was offset by far lower overall rates of admission with severe malaria. Across all types of community malaria risk, malaria admissions were relatively uncommon after the fifth birthday.

“There have been concerns that with a reduction in malaria transmission through intervention would lead to a delayed immunity shifting the malaria burden into older age groups”, says Senior author Professor Bob Snow from the Kenya Medical Research Institute-Wellcome- Oxford University collaboration in Kenya, “Our data show that the age of severe malaria is shifted to older age groups with declining transmission intensity. Despite this shift to older children in lower transmission settings, the overall severe malaria burden remains very low and severe malaria remains predominantly a problem of children below five years of age”.

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