Abstract
BackgroundIndoor residual spraying of insecticide (IRS) is a key intervention for reducing the burden of malaria in Africa. However, data on the impact of IRS on malaria in pregnancy and birth outcomes is limited.MethodsAn observational study was conducted within a trial of intermittent preventive therapy during pregnancy in Tororo, Uganda. Women were enrolled at 12–20 weeks of gestation between June and October 2014, provided with insecticide-treated bed nets, and followed through delivery. From December 2014 to February 2015, carbamate-containing IRS was implemented in Tororo district for the first time. Exact spray dates were collected for each household. The exposure of interest was the proportion of time during a woman’s pregnancy under protection of IRS, with three categories of protection defined: no IRS protection, >0–20 % IRS protection, and 20–43 % IRS protection. Outcomes assessed included malaria incidence and parasite prevalence during pregnancy, placental malaria, low birth weight (LBW), pre-term delivery, and fetal/neonatal deaths.ResultsOf 289 women followed, 134 had no IRS protection during pregnancy, 90 had >0–20 % IRS protection, and 65 had >20–43 % protection. During pregnancy, malaria incidence (0.49 vs 0.10 episodes ppy, P = 0.02) and parasite prevalence (20.0 vs 8.9 %, P < 0.001) were both significantly lower after IRS. At the time of delivery, the prevalence of placental parasitaemia was significantly higher in women with no IRS protection (16.8 %) compared to women with 0–20 % (1.1 %, P = 0.001) or >20–43 % IRS protection (1.6 %, P = 0.006). Compared to women with no IRS protection, those with >20–43 % IRS protection had a lower risk of LBW (20.9 vs 3.1 %, P = 0.002), pre-term birth (17.2 vs 1.5 %, P = 0.006), and fetal/neonatal deaths (7.5 vs 0 %, P = 0.03).ConclusionIn this setting, IRS was temporally associated with lower malaria parasite prevalence during pregnancy and at delivery, and improved birth outcomes. IRS may represent an important tool for combating malaria in pregnancy and for improving birth outcomes in malaria-endemic settings.Trial Registration Current Controlled Trials Identifier NCT02163447Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-016-1489-x) contains supplementary material, which is available to authorized users.
Highlights
Indoor residual spraying of insecticide (IRS) is a key intervention for reducing the burden of malaria in Africa
In a recent cross-sectional study performed in Tororo, a highly endemic district in Uganda where nearly 70 % of pregnant women reported using a LLIN, the prevalence of placental malaria was 62 % in women who had received ≥two doses of intermittent preventive treatment during pregnancy (IPTp)-SP, and nearly 10 % of children were born with low birth weight (LBW) [5]
Measurements of female Anopheles mosquitoes collected per household per night in Tororo were lower from February to May 2015, after IRS, compared with February–May 2014 (5.4 vs 33.7 female Anopheles mosquitoes per house per night, P < 0.001) (Fig. 1)
Summary
Indoor residual spraying of insecticide (IRS) is a key intervention for reducing the burden of malaria in Africa. In sub-Saharan Africa, over 30 million pregnancies occur annually in areas where malaria is endemic, and each year malaria in pregnancy is estimated to cause nearly one million low birth weight (LBW) deliveries and up to 100,000 infant deaths [1,2,3] Given this high burden of disease, the World Health Organization (WHO) recommends the implementation of malaria preventive measures in all African countries where Plasmodium falciparum remains endemic, including the use of longlasting, insecticide-treated nets (LLINs) and intermittent preventive treatment during pregnancy (IPTp) with sulfadoxine-pyrimethamine (SP) [4]. New interventions to prevent malaria during pregnancy and improve birth outcomes are urgently needed
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