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

 

Myanmar Election: UNICEF Urges Prioritisation Of Children

With 99 days to go before Myanmar elections, UNICEF urges candidates make children the clear winner More>>

Liberia Thousands Of Unregistered Children Born During Ebola Crisis

Thousands of unregistered children born in Liberia during Ebola crisis at risk of exploitation – UNICEF More>>

UN Refugee Agency Envoy Angelina Jolie Visits Myanmar

UNHCR Special Envoy Angelina Jolie Pitt (left) in Myitkyina township, Kachin State, Myanmar, meeting with some of the 100,000 displaced people who currently live there. Photo: UNHCR/T.Stoddart More>>

As Health Needs Rise In Somalia, Funding Hits New Low

As health needs rise in Somalia, funding hits new low, cutting off 1.5 million from care – UN More>>

Need To End Violence Against Children In Conflict

‘We should be outraged’ more not being done to end violence against children in conflict – UNICEF chief More>>

On Mandela Day, UN Joins Call To Promote Community Service

Nelson Mandela, then Deputy President of the African National Congress of South Africa, raises his fist in the air while addressing the Special Committee Against Apartheid in the General Assembly Hall. UN Photo/P. Sudhakaran More>>

Some $3.2 Billion Needed For Ebola Recovery Efforts

Some $3.2 billion needed for Ebola recovery efforts in Guinea, Liberia and Sierra Leone – UN More>>

World Day: UN Spotlights Plight Of Vulnerable Populalations

Syrian refugees fleeing the fighting near the Syrian city of Kobani wait in a holding area before boarding buses in Turkey (September 2014). Photo: UNHCR /I. Prickett More>>

Afghanisatan: Direct Talks Between Government And Taliban

The United Nations Security Council has welcomed the recently held direct talks between Afghan Government and Taliban representatives as a step towards “peace and reconciliation” in the region. More>>

Eradicating World Hunger By 2030

Agriculture workers collect carrots on a farm in Chimaltenango, Guatemala. Photo: World Bank/Maria Fleischmann More>>

Bangladesh: Flood Leads To UN Agency Providing Food Relief

Anwar Hossain unloads cartons of High Energy Biscuits from a pickup truck and transfers them to a distribution center in Kawar Khop union, Ramu upazila, Cox’s Bazar, Bangladesh. Photo: WFP/Kamrul Mithon More>>

Get More From Scoop

 
 
 
 
 
World
Search Scoop  
 
 
Powered by Vodafone
NZ independent news