Benefits of treated malaria bed nets persist into adulthood, 22-year study finds
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A two-decade study of the impact of treated mosquito bed nets for malaria control in Tanzania found that the benefits of using the nets in early childhood persisted into adulthood, assuaging some immunity-related fears.
“It has been hypothesized that in high-transmission settings, malaria control in early childhood (younger than 5 years of age) might delay the acquisition of functional immunity and shift child deaths from younger to older ages,” Günther Fink, PhD, a researcher at the Swiss Tropical and Public Health Institute, and colleagues wrote in The New England Journal of Medicine.
Fink and colleagues analyzed data from a 22-year cohort study of 6,706 children in southern Tanzania who used treated bed nets with varying frequency: one-quarter never slept under a net, another quarter slept under a net some of the time, and half regularly slept under a net.
They found that participants reported during community outreach visits early in their life to have used treated nets at half of these visits or more had a 43% lower risk for death (HR = 0.57; 95% CI, 0.45-0.72) compared with participants who were reported to have used treated nets at less than half the visits.
The first group — participants who reported using a net during at least half of these community outreach visits early in their life — had a 7% lower risk for death between age 5 years and adulthood (HR = 0.93; 95% CI, 0.58-1.49).
This “suggests that the survival benefits of insecticide-treated nets were large and persisted to adulthood given a moderate level of community coverage,” Fink and colleagues wrote.
They noted that their study contained no direct measure of immune function, although they said “it could be argued that survival to adulthood in a malaria-endemic area is itself a reflection of functional immunity.”
“Although there is robust evidence of survival gains from treated nets among children younger than 5 years of age, the long-term effects remain little studied, particularly in areas of high transmission,” they wrote. “Our results suggest substantial long-term benefits of childhood use of treated nets. These results are robust across a wide range of empirical specifications and imply that concerns regarding increased mortality in later childhood or adolescence — which might, in theory, result from delays in developing functional immunity — are not warranted.”