WHO and other organisations promote the use of insecticide treated bednets (ITN) to prevent malaria. The use of nets is based on the hypothesis that malaria is spread by mosquito bites and nets prevent bites. Insecticide treated nets not only prevent a mosquito from biting someone sleeping underneath but also kill any insect that lands on them. WHO claim that if ITNs are in widespread use the reduction in insect numbers reduces overall malaria burden. I am unaware of any studies that prove this hypothesis.
However, an analysis in Malaria World this week on the 2019 Ghana Malaria Indicator Survey had a clue that sleeping under bednets has no benefit. ‘Malaria prevalence dynamics and risk covariates among children under 5 in Ghana: insights from a Bayesian multilevel approach’ by Asosega et al has several interesting findings. Children in wealthier homes are less likely to test positive for malaria than those with poor or middle incomes (P=0.24 vs 0.32). Children with severe anaemia (low iron) are more likely to test positive than those mild or not anaemic (P=0.54 vs 0.26). These data may suggest that children who are better fed are less likely to have malaria.
And there was no significant benefit associated with sleeping under an ITN (P=0.29 vs 0.30). In households that owned bednets there was slightly less malaria (P=0.29 vs 0.32) but this is not significant either. But most interesting of all was a reference in the discussion to ‘Factors associated with the risk of malaria among children: analysis of 2021 Nigeria Malaria Indicator Survey’ by Isiko et al published in April 2024 that found that having a bednet for sleeping under was positively associated with malaria incidence (P=0.1848 vs 0.1280). The authors explain the result by suggesting ‘… a potential over-reliance on ITNs as the sole preventive measure, neglecting other malaria prevention strategies’. Perhaps breathing air that has passed through an insecticide treated net is not healthful. Or perhaps it is just a random result?
There are a number of other interesting findings in this Nigeria study which concur with my earlier postings Occurrence of Malaria associated with Poverty – Tanzania Study and Study in Ghana Suggests Poverty is the Major Factor in Occurrence of Malaria. Higher malaria associated with other water source than improved source (P=0.2484 vs 0.1552), rudimentary wall than finished wall (P=0.2253 vs 0.1348), primary than secondary education of mother (P=0.1923 vs 0.1366) and lower wealth index poor (P=0.1870) vs rich (P=0.1315).
Also interesting is that children whose mothers had been exposed to malaria messaging within 6 months before the study showed a heightened risk of contracting malaria compared to those whose mothers hadn’t received such information (P=0.1875 vs 0.1487). How good is the messaging if it increases occurrence of the illness?
Picture from kesontechs.com