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  • Genetic markers offer hope for tackling drug-resistant malaria

[MANILA] Researchers have identified what could be key genetic markers for a drug-resistant malaria strain found in the Mekong subregion of South-East Asia, and will use these findings to try to reduce the disease's incidence in Myanmar.

In a report published in the Proceedings of the National Academy of Sciences last month (17 December), researchers from Cambodia, Europe, Thailand and the United States have identified four genetic mutations in the malaria parasite that show promise as markers for the artemisinin-resistant form of the
disease.

Christopher Plowe, a researcher at the University of Maryland School of Medicine, United States, and senior author of the paper, tells SciDev.Net that, while there is no clear evidence yet of artemisinin resistance outside the Mekong area, earlier forms of resistance to other antimalarial drugs emerged in western Cambodia before spreading across Asia and then to Africa, resulting in a huge rise in global malaria deaths.

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  • Genetic markers in a drug-resistant form of malaria parasite seem to be linked to its resistance
  • The mutations could be used in tests to target this hard-to-treat form of the disease
  • Further trials into the markers are to be carried out in Myanmar

"We fear the same could happen with artemisinin-resistant malaria. But we don't have a good way to map its distribution so we can try to eliminate it before it disseminates," he says.

Plowe says the markers could be used to develop tests that will hopefully allow the geographical range of the resistant strain to be measured.

Pascal Ringwald, coordinator for drug resistance and containment at the WHO's Global Malaria Programme, agreesthat the study "will help to better monitor the presence of artemisinin-resistant malaria parasites".

The WHO recommends artemisinin drugs as the frontline treatment for the most lethal species of the malaria parasite, Plasmodium falciparum.

But in 2006, several researchers observed increasing failure rates of artemisinin-based therapies on the Thailand-Cambodia border.

The researchers involved in the new study discovered the four potential markers in trials in Bangladesh, Cambodia and Thailand by seeing if mutations in the parasite
genome were associated with resistance to the drug.

"We did this study hoping to identify molecular markers of resistance. If we can identify such markers, it becomes very easy to map the extent and track the spread of resistance by analysing the parasite DNA in drops of human blood collected on paper," Plowe explains.

Identifying these markers will allow Plowe to conduct further investigations into the markers in Myanmar, which has the most malaria cases in South-East Asia. His research team will track the spread of artemisinin-resistant malaria and train local investigators to help their country cope with the problem.

"If these mutations are predictive of clinical resistance in the field, we plan to use them for surveillance to help
public health officials target their malaria-elimination efforts to the highest priority areas, namely those where artemisinin-resistant malaria has appeared," Plowe says.

This article has been produced by SciDev.Net's South-East Asia & Pacific desk.



References

Proceedings of the National Assembly of Sciences doi: 10.1073/pnas.1211205110

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