Artemisinin resistance – threats and responses

WWARN event
© Andrea Stewart

Professor Nick White, Professor of Tropical Medicine at Mahidol Research Centre in Bangkok, Thailand and Dr Christian Nsanzabana, Clinical Coordinator for the Worldwide Antimalarial Research Network, based at Oxford University’s Centre for Tropical Medicine, spoke in London last week about the serious global health risk of anti-malarial drug resistance. The event took place on the eve of World Malaria Day in the London School of Hygiene & Tropical Medicine.

Malaria kills an estimated 627,000 people each year, most of whom are small children living in impoverished regions of Africa (WHO World Malaria Report 2013). In recent years, significant progress has been made to cure malaria patients, mostly thanks to the introduction of artemisinin combination therapies (ACTs) and effective bed nets to treat and protect patients. Yet despite this progress, total eradication of malaria has not been achieved and the disease still poses a significant threat to the lives of more than 3 billion people worldwide in malaria endemic countries such as Thailand, Cambodia, Myanmar, Mali, Nigeria and the Democratic Republic of Congo.

During the World Malaria Day 2014 presentations, Dr Nsanzabana discussed the historical background of drug resistance and explained how this is not a new phenomenon; it occurred with serious consequences in the 1950s with then widely used drugs like chloroquine. Dr Nsanzabana explained that although existing drugs remain effective in treating patients each year, there are concerning signs that some patients in Southeast Asia are no longer responding to ACT treatment.

Professor White, who was one of the first researchers to confirm the existence of resistance in 2007, confirmed that not enough has been done to stop the spread of further resistance in the last few years. He shared a number of results from an ambitious Oxford University lead research programme in Asia (Tracking Resistance to Artemisinin Collaboration), which is looking at the emergence and spread of resistance in multiple countries over the last three years. These results clearly demonstrate that the most commonly used anti-malarial drugs are beginning to fail in some areas. Prof. White went on to highlight that there has been a rapid increase in the number of patients who are not cured effectively, and that this also now occurring in new areas on the border of Bangladesh and Myanmar. Evidence suggests that spread and further emergence of resistance is very serious and could lead to resistance in other parts of Asia and eventually Africa, with potentially devastating consequences.  

If you have a problem such as malaria, the challenge is that you spend a lot of time researching it, considering the options, but by the time you have finished it has already become a lot more serious. I think we have not got the time to continue with this approach. We need to move forward with resistance containment strategies without all the specific evidence we need, otherwise it will be too late and it will have reached Africa. Malaria and drug resistance is a terrible threat which history has proven will likely kill hundreds of thousands of children.”

Dr Nsanzabana concluded with examples of how existing ACT drug treatments need to be carefully monitored and analysed to ensure that they keep working well in Asia and most importantly in Africa for as long as possible. He shared the results from a partnership between more than 100 researchers, including several experts from Oxford University, who are concluding three research studies that identify why some antimalarial drug dosing recommendations may need to be adjusted to treat malaria more effectively. In a series of papers, under review for release in the coming months, the WWARN study groups will recommend the best treatment regimens to ensure that patients, especially children under the age of 5 years, continue to be cured for the most aggressive forms of malaria.

What remains clear from both talks is that malaria mortality rates are declining, and significant achievements have been made to prevent and treat patients with ACTs in the last 10 years. However, if urgent action isn’t taken to stop the spread of drug resistance, the use of monotherapy medicines, and the dissemination of counterfeit or substandard drugs, it is possible that the more lives will be lost and the fight to eradicate malaria completely will never be achieved.

To find out more about antimalarial resistance visit the Centre for Tropical Medicine website and the Worldwide Antimalarial Resistance Network website.

Review of ‘Artemisinin Resistance - threats and responses’ kindly provided by Andrea Stewart, Head of Communications & Advocacy, Worldwide Antimalarial Resistance Network (WWARN), Centre for Tropical Medicine based at CCVTM, Nuffield Department of Medicine. For more information email andrea.stewart@ndm.ox.ac.uk