Resistance spread 'compromising' fight against malaria
By Matt McGrath
Science reporter, BBC WorldService
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Scientists have found new evidence that resistance to the front-line
treatments for malaria is increasing.
They have confirmed that resistant strains of the malaria parasite on
the border between Thailand and Burma, 500 miles (800km) away from
previous sites.
Researchers say that the rise of resistance means the effort to
eliminate malaria is "seriously compromised".
The details have been published in The Lancet medical journal.
For many years now the most effective drugs against malaria have been
derived from the Chinese plant, Artemisia annua . It isalso known as
sweet wormwood.
In 2009 researchers found that the most deadly species of malaria
parasites, spread by mosquitoes, were becoming more resistant to these
drugs in parts of western Cambodia.
This new data confirms that these Plasmodium falciparum parasites that
are infecting patients morethan 500 miles away on the border between
Thailand and Burma are growing steadily more resistant.
The researchers from the Shoklo Malaria Research Unit measured the
time it took the artemisinin drugs to clear parasites from the
bloodstreams of more than3,000 patients. Over the nine years between
2001 and 2010, they found that drugs became less effectiveand the
number of patientsshowing resistance rose to 20%.
Prof Francois Nosten, who is part of the research teamthat has carried
out the latest work, says the development is very serious.
"It would certainly compromise the idea of eliminating malaria that's
for sure and will probably translate into a resurgence of malaria in
many places," he said.
'Untreatable malaria'
Another scientist involved with the study is Dr Standwell Nkhoma from
the Texas Biomedical Research Institute.
"Spread of drug-resistant malaria parasites within South East Asia and
overspill into sub-Saharan Africa, where most malaria deaths occur,
would be a public health disaster resulting in millions of deaths."
The drug artemisinin is derived from the Artemisia annua plant
The scientists cannot tell if the resistance has moved because
mosquitoes carrying the resistant parasites have moved to the Burmese
border or if it has arisen spontaneously among the population there.
Either way the researchers involved say it raises the spectre of
untreatable malaria.
"Either the resistance has moved and it will continue to move and will
eventually reach Africa. Or if it has emerged, now thatartemisinin is
the standard therapy worldwide then it means it could emerge
anywhere," Prof Nosten told the BBC.
"If we were to lose artemisinin then we don't have any new drugs in
the pipeline to replace them. We could be going back 15years to where
cases were very difficult to treat because of the lack of an
efficacious drug."
Artemisinin is rarely used on its own, usually being combined with
older drugsto help fight the rise of resistance. These artemisinin
based combination therapies are now recommended by the World Health
Organization as the first-line treatment and have contributed
substantially to the recent decline in malaria cases in many regions.
Prof Nosten says the current spread of resistancecould be similar to
what happened in the 1970s with chloroquine, a drug that was once a
front-line treatment against the disease.
"When chloroquine resistance reached Africa in the middle of the 1970s
it translated into a large increase in the number of cases and the
number of children who died increased dramatically."
In a separate paper published in the journal Science researchers have
identified a region of the malaria parasite genome that is linked to
resistance to artemisinin.
Dr Tim Anderson, from Texas Biomed who led this study, says that while
mapping the geographical spread of resistance can be challenging it
may be hugely beneficial.
"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 the further
spread of resistance."
According to the World Malaria Report 2011 malaria was responsible
forkilling an estimated 655,000 people in 2010 - more than one every
minute. A majority of thesewere young children and pregnant women/
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