Community Delivery of Preventive Malaria Treatment to Pregnant Women Does Not Increase Drug Resistance

Providing preventive malaria treatment to pregnant women (IPTp) through community health workers (C-IPTp) does not increase the prevalence of drug-resistant parasites, at least in the short term, according to a study conducted in four sub-Saharan countries and led by the Barcelona Institute for Global Health (ISGlobal), an institution supported by “la Caixa” Foundation. The results, published in The Lancet Global Health, reinforce C-IPTp as a valuable strategy to protect the health of pregnant women and their babies in malaria-endemic regions.

Malaria in pregnancy is a major threat to the health of both mother and baby. For this reason, the WHO recommends that pregnant women receive preventive malaria treatment (IPTp) with sulfadoxine-pyrimethamine (SP) at each antenatal visit, starting in the second trimester of gestation. However, the effectiveness of this strategy can be compromised by the development of parasite resistance to the drugs.

A novel approach that increased uptake of IPTp

Six years ago, the TIPTOP project, co-led by ISGlobal and Jhpiego and funded by Unitaid, was launched to test a novel community-based approach for increasing the access to IPTp in four sub-Saharan countries (Democratic Republic of Congo, Madagascar, Mozambique and Nigeria). The approach proved successful: all districts where C-IPTp was implemented reached or exceeded the target of at least 50% of eligible pregnant women receiving the preventive treatment (up from less than 25% before the intervention), without reducing antenatal care attendance.

“Given the potential benefits of scaling up community delivery of IPTp, it was important to assess whether it could lead to an increase in parasite resistance to SP,” explains Clara Menéndez, principal investigator of the project, director of ISGlobal’s Maternal, Child and Reproductive Health Initiative and researcher at the Manhiça Health Research Center (CISM).

With no change in molecular markers of resistance

In this study, the research team evaluated the prevalence of molecular markers of resistance to SP before and after C-IPTp implementation. To do this, they collected dried blood spots from more than 2,000 children under five years of age with clinical malaria before (in 2018) and after three years (in 2021) of C-IPTp implementation in two neighbouring areas per country: one where the C-IPTp intervention took place, and one where IPTp was only provided at health facilities. They then used these samples to analyse the presence of specific genetic mutations associated with resistance to SP in the P. falciparum parasite.

Overall, the results show that there was no significant change in the prevalence of molecular markers associated with resistance to SP over time. They also confirm that malaria chemoprevention interventions do not inevitably lead to increases in resistance, and that even high rates of resistance do not necessarily impair chemoprevention efficacy. As first author Antía Figueroa-Romero explains, “an increase in mutation prevalence does not necessarily lead to meaningful increases in drug resistance. Other important factors may come into play, such as the individual’s immunity to malaria, drug metabolism, or nutritional status”.

“Our findings provide reassurance to policy makers that C-IPTp increases uptake of IPTp without compromising its efficacy and that it is a valuable strategy to optimise malaria control during pregnancy,” says co-author Raquel González, ISGlobal malaria in pregnancy expert and epidemiology coordinator of the TIPTOP project.

Reference

Figueroa-Romero Antía, Bissombolo D, Meremikwu M et al. Prevalence of molecular markers of resistance to sulfadoxine–pyrimethamine before and after community delivery of intermittent preventive treatment of malaria in pregnancy in sub-Saharan Africa: a multi-country evaluation. Lancet Glob Health 2023, 11:e1765-74. doi: 10.1016/S2214-109X(23)00414-X