Mathematical model is new tool in fight against malaria

Malaria is a life-threatening disease caused by parasites and spread to humans through infected mosquitoes. It is preventable and curable, yet resistance to current antimalarial drugs is causing an avoidable loss of life.

According to the World Health Organization (WHO), there were an estimated 241 million cases of malaria worldwide in 2020, with over 600,000 deaths.

To tackle this issue, an international research team used data from the WorldWide Antimalarial Resistance Network (WWARN), a global, scientifically independent collaboration, to map the prevalence of genetic markers that show resistance to Plasmodium falciparum – the parasite that causes malaria.

Lead author associate professor Jennifer Flegg from the University of Melbourne said malaria has devastating impacts on lower-income countries and effective treatment is key to elimination.

“The antimalarial drug sulfadoxine-pyrimethamine (SP) is used in various preventative malaria treatment programmes in Africa, particularly for infants, young children, and during pregnancy. But we know its efficacy as a treatment is threatened in areas where resistance to SP is high,” Flegg said.

She added: “The statistical mapping tool we have developed is critical for health organisations to understand the spread of antimalarial resistance. The model takes in the data that is available and fills in the gaps by making continuous predictions in space and time.

“Health agencies can use this tool to understand when and where SP is appropriate to use as part [of] preventive malaria treatments and where other antimalarial methods may need to be explored.”

Professor Karen Barnes, Head of WWARN Pharmacology and Elimination, said there is a rapidly increasing need for malaria chemoprevention (drugs that prevent malaria infections), but there are currently limited treatment options available.

“This timely evidence of the extent of SP resistance across Africa will help to inform where SP preventive treatment, alone or in combination with other antimalarials, would be most likely to have the greatest impact,” she explained.

Meanwhile, Professor Feiko ter Kuile, head of WWARN’s Malaria in Pregnancy Scientific Group, said the updated model of SP resistance in Africa was long overdue.

He said: “A lot of the resistance mapping has understandably focused on the emerging resistance to the artemisinin-based antimalarials used for treating malaria. Increasing resistance of the malaria parasite to sulfadoxine-pyrimethamine in Africa has been a concern for several decades. But easily accessible resistance data was lacking.

“This study combines all the available SP resistance data from the last two decades in a single model. It allows national malaria control programmes and researchers to get much-needed data on resistance in a given area in a given year.

“This allows us to understand better the impact of sulfadoxine-pyrimethamine resistance on the effectiveness of these preventive interventions and determine if, and when, to consider alternative drugs for chemoprevention.”

Flegg concluded that the research tool “should help guide health policies that will bring the World Health Organisation’s ambitious target of eliminating malaria by 2030 one step closer”.

The team included researchers from the University of Melbourne in Australia, the University of Oxford in the UK, Johnson C Smith University in the US, the University of Cape Town, and the University of Witwatersrand in South Africa.