Tropical Health Matters

Malaria Journal released three articles ranging from the relation between malaria and agricultural irrigation, artemisinin resistance on the Myanmar-China border, and efforts at costing malaria elimination interventions. PLoS Medicine examined the quality of malaria clinical management in children. Finally, Frontiers in Cellular and Infection Microbiology reported on a new drug against malaria and toxoplasmosis. Click on links to read more details.

Minimal tillage and intermittent flooding farming systems show a potential reduction in the proliferation of Anopheles mosquito larvae in a rice field in Malanville, Northern Benin

Irrigation systems have been identified as one of the factors promoting malaria disease around agricultural farms in sub-Saharan Africa. However, if improved water management strategy is adopted during rice cultivation, it may help to reduce malaria cases among human population living around rice fields.

A clear reduction of larva density was observed with both intermittent flooding systems applied to minimal tillage (MT?+?IF?+?NL) and intermittent flooding applied to deep tillage (DT?+?IF?+?AL), showing that intermittent flooding could reduce the abundance of malaria vector in rice fields. Recommending intermittent flooding technology for rice cultivation may not only be useful for water management but could also be an intentional strategy to control mosquitoes vector-borne diseases around rice farms.

No evidence of amplified Plasmodium falciparum plasmepsin II gene copy number in an area with artemisinin-resistant malaria along the China–Myanmar border

The emergence and spread of artemisinin resistance in Plasmodium falciparum poses a threat to malaria eradication, including China’s plan to eliminate malaria by 2020. Piperaquine (PPQ) resistance has emerged in Cambodia, compromising an important partner drug that is widely used in China in the form of dihydroartemisinin (DHA)-PPQ. Several mutations in a P. falciparum gene encoding a kelch protein on chromosome 13 (k13) are associated with artemisinin resistance and have arisen spread in the Great Mekong subregion, including the China–Myanmar border. Multiple copies of the plasmepsin II/III (pm2/3) genes, located on chromosome 14, have been shown to be associated with PPQ resistance.

DHA-PPQ for uncomplicated P. falciparum infection still showed efficacy in an area with artemisinin-resistant malaria along the China–Myanmar border. There was no evidence to show PPQ resistance by clinical study and molecular markers survey. Continued monitoring of the parasite population using molecular markers will be important to track emergence and spread of resistance in this region.

Costing malaria interventions from pilots to elimination programmes

Malaria programmes in countries with low transmission levels require evidence to optimize deployment of current and new tools to reach elimination with limited resources. Recent pilots of elimination strategies in Ethiopia, Senegal, and Zambia produced evidence of their epidemiological impacts and costs. There is a need to generalize these findings to different epidemiological and health systems contexts. Drawing on experience of implementing partners, operational documents and costing studies from these pilots, reference scenarios were defined for rapid reporting (RR), reactive case detection (RACD), mass drug administration (MDA), and in-door residual spraying (IRS). These generalized interventions from their trial implementation to one typical of programmatic delivery. In doing so, resource use due to interventions was isolated from research activities and was related to the pilot setting. Costing models developed around this reference implementation, standardized the scope of resources costed, the valuation of resource use, and the setting in which interventions were evaluated. Sensitivity analyses were used to inform generalizability of the estimates and model assumptions.

Populated with local prices and resource use from the pilots, the models yielded an average annual economic cost per capita of $0.18 for RR, $0.75 for RACD, $4.28 for MDA (two rounds), and $1.79 for IRS (one round, 50% households). Intervention design and resource use at service delivery were key drivers of variation in costs of RR, MDA, and RACD. Scale was the most important parameter for IRS. Overall price level was a minor contributor, except for MDA where drugs accounted for 70% of the cost. The analyses showed that at implementation scales comparable to health facility catchment area, systematic correlations between model inputs characterizing implementation and setting produce large gradients in costs. Prospective costing models are powerful tools to explore resource and cost implications of policy alternatives. By formalizing translation of operational data into an estimate of intervention cost, these models provide the methodological infrastructure to strengthen capacity gap for economic evaluation in endemic countries. The value of this approach for decision-making is enhanced when primary cost data collection is designed to enable analysis of the efficiency of operational inputs in relation to features of the trial or the setting, thus facilitating transferability.

Quality of clinical management of children diagnosed with malaria: A cross-sectional assessment in 9 sub-Saharan African countries between 2007–2018

Appropriate clinical management of malaria in children is critical for preventing progression to severe disease and for reducing the continued high burden of malaria mortality. This study aimed to assess the quality of care provided to children under 5 diagnosed with malaria across 9 sub-Saharan African countries. We used data from the Service Provision Assessment (SPA) survey. SPAs are nationally representative facility surveys capturing quality of sick-child care, facility readiness, and provider and patient characteristics across 9 countries, including Uganda (2007), Rwanda (2007), Namibia (2009), Kenya (2010), Malawi (2013), Senegal (2013–2017), Ethiopia (2014), Tanzania (2015), and Democratic Republic of the Congo (2018).

In this study, we found that a majority of children diagnosed with malaria across the 9 surveyed sub-Saharan African countries did not receive recommended care. Clinical management is positively correlated with the stocking of essential commodities and is somewhat improved in more recent years, but important quality gaps remain in the countries studied. Continued reductions in malaria mortality will require a bigger push toward quality improvements in clinical care. Despite increases in the distribution of malaria tests and effective antimalarial medications, significant gaps in the quality of care for pediatric malaria are present in these 9 countries. Further improvements in quality of malaria care may require a better understanding of remaining barriers and facilitators to appropriate management.

Novel drug could be a powerful weapon in the fight against malaria and toxoplasmosis

Princeton researchers are making key contributions toward developing a promising new treatment for the widespread and devastating diseases toxoplasmosis and malaria.
The Princeton scientists specialize in preparing the drug compound into a medicine that is both safe and effective for humans and able to reach its intended sites of action in the body in sufficient doses. An international team of scientists found the new drug—designated JAG21—to be highly effective against parasites in cell-based studies in the lab. After the discovery, team representatives contacted Princeton’s Robert Prud’homme for help in translating the JAG21 compound into a deliverable medication. Prud’homme is a co-author of a study, published in June 2020 in Frontiers in Cellular and Infection Microbiology, that describes the compound and its excellent preliminary results in mice.

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