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 Using fragment-based approaches to discover new antibiotics
21.06.2018 | SLAS (Society for Laboratory Automation and Screening)

nachricht Scientists learn more about how gene linked to autism affects brain
19.06.2018 | Cincinnati Children's Hospital Medical Center

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: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Graphene assembled film shows higher thermal conductivity than graphite film

22.06.2018 | Materials Sciences

Fast rising bedrock below West Antarctica reveals an extremely fluid Earth mantle

22.06.2018 | Earth Sciences

Zebrafish's near 360 degree UV-vision knocks stripes off Google Street View

22.06.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>