Malaria is one of the most preventable causes of adverse pregnancy outcomes, but any gains made in the last decade at preventing the mosquito-borne illness in pregnancy may be lost as resistance to the prophylactic treatment sulfadoxine-pyrimethamine is rising. A new series in The Lancet Infectious Diseases takes stock of the current challenges facing women at risk of malaria infections in pregnancy.
The past 10 years have seen a number of successes, the journal authors write, including lowered prevalence of Plasmodium vivax in Asia and Latin America and decreasing rates of Plasmodium falciparum in parts of Africa, but access to easy screening and testing is still lacking in resource-poor countries.
Pregnant women, the authors suggest, are malaria's sentinels because they frequent health clinics in low-resource countries. Malaria-endemic countries would do well to focus their resources on this group.
"A deeper understanding of the biology of malaria infection in pregnancy will help to develop new approaches for the successful implementation of malaria elimination strategies to achieve a world free of malaria,” the authors write.
Deficits in prevention, treatment
Malaria, along with poor nutrition, is one of the leading causes of low birthweight in many parts of the world, including sub-Saharan Africa. Moreover, malaria can interfere with placental development and function, leading to intrauterine growth restriction.
One of the most cost-effective ways to limit malaria exposure is to ensure pregnant women sleep under an insecticide-treated net (ITN), but a study in 2014 showed that only 39% of pregnant women in sub-Saharan Africa used an ITN.
Health officials also recommend in endemic countries that pregnant women be treated with intermittent preventive treatment in pregnancy (IPTp) of sulfadoxine–pyrimethamine. But in 2015, only 31.5% of eligible pregnant women received three or more doses of IPTp.
Unfortunately, alternative IPTp candidates have not proved to be as effective as sulfadoxine–pyrimethamine, which is susceptible to resistance. Currently, only 7% of sub-Saharan pregnancies occur in places with substantial rates of antimalarial resistance, but that number is expected to grow, the authors said.
Of five alternative IPTp candidates tested in the last decade, only dihydroartemisinin–piperaquine has shown promise in pregnant women. Confirmatory trials are ongoing to establish if the treatment is safe for newborns.
One promising solution to close these treatment and prevention gaps is the identification of VAR2CSA, a malaria vaccine that offers protective immunity against P falciparum in pregnancy. The vaccine is currently in phase 1 trials. Young women, the authors write, would be ideal candidates for the vaccine.
Monitoring drug effects in pregnancy
Artemisinin-based combination treatments should be used to treat malaria in the second and third trimesters, the authors reported. In most trials, these treatments have a 85% to 90% success rate in pregnant women. Currently, the World Health Organization recommends the use of quinine with clindamycin for treating malaria in the first trimester, but it may soon be revising its recommendation to include artemisinin-based therapies.
Continued pharmacovigilance of first-trimester exposure to antimalarial drugs is needed to further understand the risks of drug exposure, the authors said.
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