Scientists in south-east
Asia call for pre-emptive strike in Burma jungle to contain resistant strain
spreading to India and Africa
By Kathleen E McLaughlin
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Mosquitoes are commonly seen as the enemy of malaria
elimination efforts.
Photograph: AP
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Within three days, medication had killed the
parasites in her blood and Daw Cho Cho felt normal, her symptoms gone. But a
month later, the malaria came back. The drugswere unable to kill all the parasites in her blood, and
they multiplied.
She is among the thousands
who have been infected with an insidiously evolving drug-resistant parasite
that may account for 80% of the malaria on this section of the Thai-Burma
border. The mosquito-borne illness is becoming resistant to the last
anti-malaria drug standing – artemisinin – largely because of counterfeit
medicines and incorrect usage.
A leading researcher at the Shoklo Malaria Research Unit (SMRU), a
research centre based on the border and funded primarily by the Wellcome Trust, is taking radical measures to stop the spread
of the new strain before it becomes uncontrollable. Dr François Nosten, SMRU's
director, has studied malaria in this border region, near where the disease
first became drug resistant, for three decades. He believes that in order to
stop it spreading to India, then Africa, where the vast majority of the world's
malaria cases occur, it's essential to chase the parasite into Burma's forests
and pre-emptively treat even people who may not be ill.
"If we don't do
anything, we think that we know what's going to happen," said Nosten,
explaining that as malaria rates decline, the strongest and most resistant
strains of the parasite survive and spread. "It has always happened like
this in the past, there's no reason to think this time will be any
different."
The level of alarm
Nosten and other scientists express over drug-resistant malaria contrasts with
how it manifests in people, in these early stages. It acts just the same as any
malaria, but is more difficult to cure. The number of cases creeps up slowly,
spreads, then explodes.
"The thing about resistance to anything –
drugs, antibacterials – is that it rises exponentially," said Nick White,
a professor with the Oxford Tropical Medicine
Research Programme who works with Nosten on this issue.
"There's a long period where it doesn't appear to be rising – and then
it's rising."
People who have had
the new strain of malaria report that it feels no different to the disease
cured in a day by artemisinin combination therapy just a few years ago. That
may change, but for now, the malaria itself doesn't cause new symptoms or more
complications – it's just becoming much more difficult to destroy.
My Yee Thaung, whose
nine-year-old son recently had malaria thought to be drug-resistant, said he
recovered, slowly, "but he's still not eating very well."
These patients are
among thousands participating in a nine-week study of their blood. The clinic,
one of five malaria centres for Burmese refugees in Thailand run by SMRU, pays
their transportation fees and a nominal amount to cover lost wages, and the
patients return to give blood samples once a week.
The number of malaria
cases has shrunk in this region dramatically in the past 30 years, since Nosten
and his team began to contain and eradicate it. When Nosten started the first
border clinic, the parasite was a major killer, infecting tens of thousands of people
each rainy season. Today, there are a few thousand cases each year. But those
that remain are more likely to contain a wilier parasite, one that is evolving
to evade what was first touted as a miracle drug.
The global implications of artemisinin losing
its edge on malaria are alarming. Worldwide, the WHO estimates there were 207 million malaria cases in
2012 and more than 600,000 deaths, and says malaria rates dropped 25% worldwide
during 2000-2012. The Institute for Health Metrics and
Evaluation uses a different methodology for tallying malaria
deaths and says the global death toll could be double what the WHO reports.
In either case,
malaria numbers have dropped dramatically in the past decade. But what remains
is even more dangerous, and Nosten warns of a potential complacency that could
allow drug-resistant malaria to erupt.
"It is an
emergency. Everyone is spending their time in meetings, giving advice, not
acting quickly enough," he said. "It looks like this time we are
going to lose."
The march of
drug-resistant malaria westward has begun. Cases are cropping up further west
in Burma, and may have entered Bangladesh. If that's the case, and history
repeats itself, this dangerous and potentially deadly parasite could move
further west into India, then drop south to Africa. It has happened twice
before with the world's best malaria drugs and researchers such as Nosten fear
a third wave is under way, negating a frontline treatment for a killer of
millions, with nothing new on the shelf to take its place.
Starting this summer and backed by the Global Fund and others, Nosten's team is
going on the offensive against malaria in Burma. His teams will establish 800
village health stations inside Burma, treating people who have the illness and
pre-emptively giving medication to entire villages where a high percentage of
people carry the malaria parasite. He believes containment – the strategy of
choice thus far – has been too limited, though malaria rates have dropped
dramatically. Elimination is now necessary.
Artemisinin-based
malaria drugs have few side-effects and most people require only a three-day
course to get rid of the parasites. Nosten faced early opposition to his plan,
but says time and options have run out, and the downsides are minimal.
"It's already
spread from the border into Myanmar [Burma]," he said. "We should
have done this three or four years ago. Now I'm afraid it could be a bit too
late."
Changing resistance
Malaria is forever
outrunning its attackers, shifting its shape to survive the drugs invented to
eradicate the parasite.
Chloroquine was
widely effective around the world, but began to lose its grip on malaria after
mass dosing in endemic areas. Malaria grew resistant to the drug by the 1950s.
Sulfadoxine-pyrimethamine, commonly sold as Fansidar, came next and proved
effective until the end of the last century, when resistance proved common.
Artemisinin, derived
from sweet wormwood, followed. China's People's Liberation Army at the behest
of the Communist party leader, Mao Zedong, developed the drug as part of a
secretive project during the Vietnam war. The highly effective drug was kept out
of the global marketplace by China but also because of global pharmaceutical
spats. In 2006, it became the world's frontline malaria treatment.
Today, artemisinin
still works within a combination drug. Because of a global abundance of fake
drugs (many made in China) and bad dosing, however, its days are numbered.
