World Video | Defence | Foreign Affairs | Natural Events | Trade | NZ in World News | NZ National News Video | NZ Regional News | Search

 


Southeast Asia: Drug-resistant malaria spread

Drug-resistant malaria has spread to critical border regions of Southeast Asia

31 July 2014

Bangkok: Drug-resistant malaria parasites have spread to critical border regions of Southeast Asia, seriously threatening global malaria control and elimination programmes, according to a study published in the New England Journal of Medicine.

The study confirms that resistance to the world’s most effective antimalarial drug, artemisinin, is now widespread in Southeast Asia. This is not the first, or even the second time the malaria parasite has developed resistance to front line drugs, and each time resistance has emerged from the same corner of Asia on the Cambodia-Thailand border.

The study, which analysed blood samples from 1241 malaria patients in 10 countries across Asia and Africa, found that artemisinin resistance in Plasmodium falciparum - the most deadly form of malaria-causing parasite – is now firmly established in Western Cambodia, Thailand, Vietnam, Eastern Myanmar and Northern Cambodia. There are also signs of emerging resistance in Central Myanmar, Southern Laos and Northeastern Cambodia.

Reassuringly, there are no signs of resistance in the three African sites included in the study, located in Kenya, Nigeria and Democratic Republic of the Congo.

The study also suggests that extending the course of antimalarial treatment in areas with established resistance – for six days rather than the standard three days – could offer a temporary solution to this worsening problem.

“It may still be possible to prevent the spread of artemisinin resistant malaria parasites across Asia and then to Africa by eliminating them, but that window of opportunity is closing fast.Conventional malaria control approaches won’t be enough – we will need to take more radical action and make this a global public health priority, without delay," said Professor Nicholas White, senior author of the study and Chairman of the Welcome Trust-funded Mahidol Oxford Tropical Medicine Research Unit (MORU), Professor of Tropical Medicine at the University of Oxford, and Chair of the Worldwide Antimalarial Resistance Network.

The study was conducted by the Tracking Resistance to Artemisinin Collaboration (TRAC) which enrolled infected adults and children at 15 trial sites in 10 malaria-endemic countries between May 2011 and April 2013. The TRAC partners examined the different responses in malaria infected patients to artemisinin treatment. Patients received a six-day antimalarial treatment, three days of an artemisinin derivative and a three day course of artemesinin combination treatment (ACT). Patients’ blood was analysed to measure the ‘parasite clearance half-life’ or rate at which the parasites are cleared from a patient’s blood.

Results showed that the median parasite clearance half-life ranged from 1.8 hours in the Democratic Republic of the Congo to 7 hours at the Thailand-Cambodia border, where artemisinin resistance has been known aboutsince 2005. The proportion of patients with parasites in their blood 72 hours after treatment, a widely used test for artemisinin resistance, ranged from 0% in Kenya to 68% in Eastern Thailand. Malaria infections that were slow to clear were also strongly associated with a single point mutation in a P. falciparum gene called kelch 13, an important validation of the recently discovered genetic marker (k13) in the DNA of the malaria parasite.

Researchers also found that patients who had slow clearing infections were also more likely to have parasite stages which can infect mosquitoes. This suggests that artemisinin-resistant P. falciparum parasites have a transmission advantage over parasites that are not resistant, which drives their spread.

“Frontline ACTs are still very effective at curing the majority of patients. But we need to be vigilant as cure rates have fallen in areas where artemisinin resistance is established,” said Dr Elizabeth Ashley, lead scientist of the TRAC study and Clinical Researcher at the Mahidol Oxford Tropical Medicine Research Unit (MORU), University of Oxford. “Action is needed to prevent the spread of resistance from Myanmar into neighbouring Bangladesh and India.”

Dr Jeremy Farrar, Director of the Wellcome Trust says: “If resistance spreads out of Asia and into Africa much of the great progress in reducing deaths from malaria will be reversed. Our ability to respond to these rapidly emerging health problems depends on swift gathering of evidence, which can be quickly translated into public health and clinical interventions that are then implemented. Antimicrobial resistance is happening now. This is not just a threat for the future, it is today's reality.”

Currently over half of the world’spopulation are at risk of malaria infection. Although there has been a substantial reduction in the number of people falling ill and dying from malaria – with approximately 3.3 million deaths prevented since 2000 – it is estimated that more than 600,000 people still die from the disease each year, most of them children under five years of age living in Africa.1

While new antimalarial medicines are indevelopment, and another paper published in the New England Journal of Medicine has shown some promising trial results for a potential new antimalarial drug in development at Novartis, they are unlikely to be available for widespread distribution for several years.

“The artemisinin drugs are arguably the best antimalarials we have ever had. We need to conserve them in areas where they are still working well,” concluded Dr Ashley.

Publication details: Elizabeth A Ashley et al. Spread of Artemisinin Resistance in Plasmodium falciparum Malaria. Advanced online publication in New England Journal of Medicine. July 31 2014; 371:411-23. DOI: 10.1056/NEJMoa1314981.

Notes to editors

•From the late 1950s to the 1970s chloroquine resistant malaria parasites spread across Asia to Africa, resulting in a resurgence of malaria infections and millions of deaths. Chloroquine was replaced by sulphadoxine-pyrimethamine (SP), but resistance to SP also emerged in Western Cambodia and spread to Africa. SP was replaced by ACTs, and now we face the prospect of history repeating itself for a third time.

•Artemisinin is the most effective drug against malaria. Artemisinin derivatives, such as artesunate, have several advantages over other antimalarial drugs such as chloroquine and mefloquine: the artemisinin derivatives act more rapidly and they have fewer side-effects. Although artemisinin derivatives can be used on their own - as a monotherapy - fears about the possible development of resistance led to recommendations that they should only be used in conjunction with one or more other drugs - as artemisinin combination therapies (ACTs).

•ACTs are now recommended by the World Health Organization as the firstline treatment for uncomplicated falciparum malaria, and they have contributed substantially to the recent decline in malaria cases in most tropical endemic regions.

•Some of key drivers of resistance in the malaria parasites are counterfeit or substandard treatments, unregulated antimalarial drug use, using artemisinin without a partner antimalarial as part of a combination treatment, and the unusual genetic structure of malaria parasites in Western Cambodia.

•The presence of kelch 13 mutations was strongly associated with a delayed parasite clearance from the patient’s system during treatment, and thus has been confirmed as a reliable marker of resistance. This will facilitate surveillance efforts going forward.

•Patients with slower parasite clearance are more likely to transmit their drug resistant strain to others.

•Treatment failure rates with artesunate-mefloquine in Thailand and with DHA-piperaquine in Cambodia have now risen more than fivefold.

•1 Malaria burden estimates from the WHO World Malaria Report 2013.

Funding
The TRAC project was funded by the UK Department for International Development (DFID). Additional support was given by the Worldwide Antimalarial Resistance Network (WWARN), the Intramural Research Program of the National Institute of Allergy and Infectious Diseases (NIAID) at the National Institutes of Health (NIH), and the Bill & Melinda Gates Foundation. The study was coordinated by MORU, the Mahidol Oxford Research Programme funded by the Wellcome Trust.

ENDS

© Scoop Media

 
 
 
 
 
World Headlines

 

Ban Condemns Killing Of Former Lesotho Military Commander

United Nations Secretary-General today condemned the killing of Lt. Gen. Maaparankoe Mahao, former Commander of the Lesotho Defence Force, on 25 June, near Maseru. More>>

Ban Welcomes US Supreme Court Ruling On Same-Sex Marriage

Ban welcomes US Supreme Court ruling guaranteeing right to same-sex marriage Lesbian, Gay, Bisexual, Transgender and Intersex (LGBTI) pride march. Photo: OHCHR/Joseph Smida More>>

UN Agency Welcomes EU Measures On Refugee Arrivals

Afghan refugees in front of the abandoned hotel Captain Elias on Kos Island, Greece, where hundreds of refugees and migrants are waiting for their registration. Photo: UNHCR/J. Akkash More>>

Increase In Voluntary Blood Donors Can Save Millions Of Lives

Increase in voluntary blood donors can save millions of lives, UN health agency says on World Day More>>

Kenya: Funding Shortage Means Food Cut To 500,000 Refugees

Funding shortage forces UN agency to temporarily cut food aid to 500,000 refugees in Kenya More>>

UN Launches Education Appeal In Fight Against Child Labour

12 June 2015 – The United Nations has announced it is marking the 2015 edition of the World Day Against Child Labour with a call for the international community to invest in quality education as a key step in the fight against child employment ... More>>

Pope Francis & UN Agency On Sustainability Of Agriculture

Pope Francis (centre) with delegates to the 39th FAO Conference during a special audience at the Vatican. Photo: FAO More>>

South Sudan: Call For De-Escalation Of In-Country Conflict

Women and children have suffered devastating attacks in South Sudan’s Unity State. Photo: UNICEF/South Sudan/Sebastian Rich More>>

Burundi: Emergency Support To Refugees Fleeing Burundi Crisis

Burundians fleeing pre-election violence rest on the shores of Lake Tanganyika in the Democratic Republic of Congo after a gruelling 22-hour boat journey. More than 100,000 Burundians have fled over the past month, arriving in Tanzania, Rwanda and ... More>>

Afghanistan: Commitment To Advancing Women's Rights

While the outgoing senior United Nations rights official in Afghanistan said she expected the human rights advances made “will be sustained, will not be rolled back, and will not be sacrificed,” she lamented the high level of violence against ... More>>

Get More From Scoop

 
 
 
 
 
World
Search Scoop  
 
 
Powered by Vodafone
NZ independent news