For the second time in recent weeks, I am glad to report that some malaria researchers are questioning the use of insecticides to combat malaria. A proof copy of a review paper by Oberlin et al entitled ‘Effect of Indoor Residual Spraying on Malaria in Pregnancy and Pregnancy Outcomes: A Systematic Review’ was included in Malaria World this week. The authors screened 1,845 abstracts and included 17 articles in their review, one in India and the others from various African nations.
There was confounding of different methods in the studies – IRS, IPTp and bednets. In nine of the 17 studies the insecticide used is not identified. Some studies looked for parasites. Others relied on self-reporting of symptoms, which can be subject to bias. Three studies claimed to detect a reduction in placental malaria in those exposed to IRS.
Just five studies examined pregnancy and neonatal outcomes. One study only showed a significant benefit in the group exposed to IRS for 90% of the pregnancy. Conversely, another showed a significant INCREASE in preterm births (PTB) in those exposed to IRS during pregnancy. Some studies showed a decrease in low birth weight (LBW) when exposed to IRS during pregnancy but not all. There were mixed results to the question of a reduction of fetal and neonatal fatalities.
However, one study evaluated the risk of external urogenital birth defects in male infants born to mothers exposed to IRS and found the risk of any urogenital birth defect was 33% greater in those exposed to IRS. Only five of the studies were considered good, including the two studies that found the most negative results. Most of the studies examined were considered fair or poor.
The authors concluded ‘…without high-quality evidence to understand the potential risks and benefits of its use, no clear endorsement of its use to protect pregnant women can be made. Caution is also warranted given demonstrated negative long-term impact on childhood neurodevelopment from prenatal exposure to certain insecticides’.
[picture from www(dot)swissmalariagroup(dot)ch]