Long-term effects of malaria prevention with insecticide-treated mosquito nets on morbidity and mortality in African children: randomised controlled trial.

Objective: The objective is to investigate the effect of malaria control with insecticide-treated mosquito nets (ITNs) regarding possible higher mortality in children protected during early infancy, due to interference with immunity development, and to assess long-term effects on malaria prevalence and morbidity.

Methods: Between 2000 and 2002, a birth cohort was enrolled in 41 villages of a malaria holoendemic area in north-western Burkina Faso. All neonates (n = 3387) were individually randomised to ITN protection from birth (group A) vs. ITN protection from age 6 months (group B). Primary outcome was all-cause mortality. In 2009, a survey took place in six sentinel villages, and in 2010, a census was conducted in all study villages.

Results: After a median follow-up time of 8.3 years, 443/3387 (13.1%) children had migrated out of the area and 484/2944 (16.4%) had died, mostly at home. Long-term compliance with ITN protection was good. There were no differences in mortality between study groups (248 deaths in group A, 236 deaths in group B; rate ratio 1.05, 95% CI: 0.889-1.237, P = 0.574). The survey conducted briefly after the rainy season in 2009 showed that more than 80% of study children carried asexual malaria parasites and up to 20% had clinical malaria.

Conclusion: Insecticide-treated mosquito net protection in early infancy is not a risk factor for mortality. Individual ITN protection does not sufficiently reduce malaria prevalence in high-transmission areas. Achieving universal ITN coverage remains a major challenge for malaria prevention in Africa.