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Chemoprevention

By Sian Clarke

First used in pregnant women, intermittent preventive treatment (IPT) with antimalarial drugs is now recommended by WHO also as an effective means to reduce the incidence of malaria in infants and young children under 5 years. Research by the LSHTM Malaria Centre, in partnership with our collaborators in malaria-endemic countries, has been pivotal in providing the vital scientific evidence to underpin these new policy recommendations. The approach, collectively termed chemoprevention, now represents the third mainstay of malaria control, alongside strategies to ensure timely access to effective treatment and use of ITNs to protect against mosquito bites. 

 

Since 2012, seasonal malaria chemoprevention (SMC) in young children has been rolled out across 12 countries in West Africa, protecting an estimated 15.7 million children in 2017. Malaria Centre researchers have been involved in monitoring the consequences of scaling up SMC, measuring the frequency of malaria cases, adverse drug reactions, and drug resistant alleles over time. Researchers at LSHTM also continue to investigate new ways to improve preventive chemotherapy – exploring the effectiveness and safety of alternative drugs for IPT in pregnancy, and whether IPT could also benefit other population groups. Trials led by LSHTM were the first to show the promise of IPT in reducing asymptomatic malaria infection and anaemia in older school-aged children; a finding recently confirmed by a meta-analysis which combines data from 11 trials across Africa.

 

Efforts to combine the preventive use of antimalarial drugs with other interventions are also being evaluated. Studies in pregnant women in Zambia have shown that IPTp can have benefits beyond malaria, also reducing the incidence of sexually-transmitted and reproductive tract infections. A trial is now underway to investigate whether adding the antibiotic/antiprotozoal drug metronidazole to preventative antimalarial treatment has further benefits. In Mali and Burkina Faso, we are working with our local collaborators to evaluate the utility of combining seasonal malaria chemoprevention with monthly azithromycin (a broad spectrum antibiotic) in preventing childhood mortality. Whereas this provided some benefit in lowering the incidence of non-malaria fevers, there was no measurable benefit in reducing overall mortality in the target group. Studies are also underway to investigate whether seasonal boosters of the RTS,S vaccine, recently licensed for use in Africa, could be used as an alternative to SMC; or whether the combination of the two interventions could provide added benefit.

 

Finally, the Malaria Centre is also involved in projects which examine the use of antimalarial drugs to treat entire populations with the aim of reducing the infectious reservoir of asymptomatic Plasmodium infections that maintain transmission. This approach, known as mass drug administration (MDA), is currently being explored as a key component within malaria elimination strategies in many countries around the world. Projects which include MDA are summarised in the elimination section.