Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Emergence of artemisinin-resistance on Thai-Myanmar border raises spectre of untreatable malaria

10.04.2012
Evidence that the most deadly species of malaria parasite, Plasmodium falciparum, is becoming resistant to the front line treatment for malaria on the border of Thailand and Myanmar is reported in The Lancet today. This increases concern that resistance could now spread to India and then Africa. Eliminating malaria might then prove impossible.
Evidence that the most deadly species of malaria parasite, Plasmodium falciparum, is becoming resistant to the front line treatment for malaria on the border of Thailand and Myanmar (Burma) is reported in The Lancet today. This increases concern that resistance could now spread to India and then Africa as resistance to other antimalarial drugs has done before. Eliminating malaria might then prove impossible.

The study coincides with research published today in Science in which researchers in south east Asia and the USA identify a major region of the malaria parasite genome associated with artemisinin resistance. This region, which includes several potential candidate genes for resistance, may provide researchers with a tool for mapping resistance.

Both studies, funded by the Wellcome Trust and the National Institutes of Health, follow reports in 2009 of the emergence of artemisinin-resistant malaria parasites in western Cambodia, 800km away from the Thailand-Myanmar border where the new cases of resistance have been observed. Resistance to artemisinin makes the drugs less effective and could eventually render them obsolete, putting millions of lives at risk.

According to the World Malaria Report 2011, malaria killed an estimated 655,000 people in 2010, mainly young children and pregnant women. It is caused by parasites that are injected into the bloodstream by infected mosquitoes. Plasmodium falciparum is responsible for nine out of ten deaths from malaria.

The most effective antimalarial drug is artemisinin; the artemisinin derivatives, most commonly artesunate, have the advantage over other antimalarial drugs such as chloroquine and mefloquine, of acting more rapidly and having fewer side-effects and, until recently, malaria parasites have shown no resistance against them. Although the drugs can be used on their own as a monotherapy, and these can still be obtained, fears over the possible development of resistance led to recommendations that they should only be used in conjunction with one or more other drugs as artemisinin-based combination therapies (ACTs). These are now recommended by the World Health Organization as the first-line treatment for uncomplicated falciparum malaria in all endemic countries. ACTs have contributed substantially to the recent decline in malaria cases in most tropical endemic regions.

In the Lancet study, researchers at the Shoklo Malaria Research Unit on the border of Thailand and Myanmar, part of the Wellcome Trust-Mahidol University-Oxford University Tropical Medicine Research Programme, measured the time taken to clear parasites from the blood stream in 3,202 patients with falciparum malaria using oral artesunate-containing medications over a ten year period between 2001 and 2010.

Over this period, the average time taken to reduce the number of parasites in the blood by a half – known as the ‘parasite clearance half-life’ – increased from 2.6 hours in 2001 to 3.7 hours in 2010, a clear sign that the drugs were becoming less effective. The proportion of slow-clearing infections – defined as a half-life of over 6.2 hours – increased over this same period from six to 200 out of every 1000 infections.

By examining the genetic make-up of the parasites, the researchers were able to provide compelling evidence that the decline in the parasite clearance rates was due to genetic changes in the parasites which had made them resistant to the drugs.

This finding is supported by the evidence reported in Science, in which the same researchers, together with an international team led by scientists at the Texas Biomedical Research Institute, San Antonio, identified a region on chromosome 13 of genome of the P. falciparum parasite that shows a strong association with slow parasite clearance rates. Whilst the actual mechanism involved is not clear, the region contains several candidate genes that may confer artemisinin resistance to the parasite.

Professor François Nosten, Director of the Shoklo Malaria Research Unit, said: “We have now seen the emergence of malaria resistant to our best drugs, and these resistant parasites are not confined to western Cambodia. This is very worrying indeed and suggests that we are in a race against time to control malaria in these regions before drug resistance worsens and develops and spreads further. The effect of that happening could be devastating. Malaria already kills hundreds of thousands of people a year – if our drugs become ineffective, this figure will rise dramatically.”
Professor Nick White, Chairman of the Wellcome Trust’s South-East Asia Major Overseas Programmes and Chair of the WorldWide Antimalarial Resistance Network (WWARN), added: “Initially we hoped we might prevent this serious problem spreading by trying to eliminate all P. falciparum from western Cambodia. Whilst this could still be beneficial, this new study suggests that containing the spread of resistance is going to be even more challenging and difficult than we had first feared.”

Dr Tim Anderson from the Texas Biomedical Research Institute, who led the genetics studies in both papers, commented: “Mapping the geographical spread of resistance can be particularly challenging using existing clinical and parasitology tools. If we can identify the genetic determinants of artemisinin resistance, we should be able to confirm potential cases of resistance more rapidly. This could be critically important for limiting further spread of resistance.

“We know that the genome region identified harbours a number of potential genes to explore further to see which ones drive artemisinin resistance. If we can pinpoint the precise gene or genes, we can begin to understand how resistance occurs.”

The Wellcome Trust-Mahidol University-Oxford Tropical Medicine Research Programme is one of the Wellcome Trust’s major overseas programmes, working to achieve the Trust’s strategic priorities, which include combating infectious diseases.

Dr Jimmy Whitworth, Head of International Activities at the Wellcome Trust, said: “These two studies highlight the importance of being vigilant against the emergence of drug resistance. Researchers will need to monitor these outbreaks and follow them closely to make sure they are not spreading. Preventing the spread of artemisinin resistance to other regions is imperative, but as we can see here, it is going to be increasingly difficult. It will require the full force of the scientific and clinical communities, working together with health policymakers.”

Craig Brierley | Research asia research news
Further information:
http://www.wellcome.ac.uk
http://www.researchsea.com

More articles from Health and Medicine:

nachricht Millions through license revenues
27.04.2017 | Rheinische Friedrich-Wilhelms-Universität Bonn

nachricht New High-Performance Center Translational Medical Engineering
26.04.2017 | Fraunhofer ITEM

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>