[health-vn] Malaria parasites 'resist drugs'

[Vern Weitzel]

http://news.bbc.co.uk/2/hi/asia-pacific/8073118.stm

Page last updated at 03:36 GMT, Friday, 29 May 2009 04:36 UK

Malaria parasites 'resist drugs'


Half the world's population is exposed to malaria

International scientists say they have found the first evidence of resistance to 
the world's most effective drug for treating malaria.
They say the trend in western Cambodia has to be urgently contained because 
full-blown resistance would be a global health catastrophe.
Drugs are taking longer to clear blood of malaria parasites than before.
This is an early warning sign of emerging resistance to a disease which kills a 
million people every year.
Until now the most effective drug cleared all malaria parasites from the blood 
within two or three days but in recent trials this took up to four or five days.
The BBC's Jill McGivering, reporting from Cambodia, says it is unclear why the 
region has become a nursery for the resistance - but the local public health 
system is weak, and the use of anti-malaria drugs is not properly controlled.
Drug defence
The artemesinin family of drugs is the world's front-line defence against the 
most prevalent and deadly form of malaria.
	
Two teams of scientists, working on separate clinical trials, have reported 
seeing the disturbing evidence that the drugs are becoming much less effective.
There is particular concern because previous generations of malaria drugs have 
been undermined by resistance which started in this way, in this part of the 
world, our correspondent reports.
The World Health Organization warned in 2006 there was a possibility the malaria 
parasite could develop a resistance to artemesinin drugs, and that there was 
particular concern about a decreased sensitivity to the drug being seen in South 
East Asia.
It urged drug firms to stop selling artemesinin on its own in order to prevent 
resistance building up.
Early results from two studies by US and UK teams have both revealed the early 
stages of resistance.
Between a third and a half of patients in the US study saw delayed clearance of 
the malaria parasite.
In the UK study, patients in the Cambodia arm of the trial took almost twice as 
long to clear the parasite as a comparison group in Thailand.
Professor Nick Day, director of the Mahidol-Oxford Tropical Medicine Research 
Unit which is carrying out the UK study, said: "Twice in the past, South East 
Asia has made a gift, unwittingly, of drug resistant parasites to the rest of 
the world, in particular to Africa," he said.
"That's the problem. We've had chloroquine and SP (sulfadoxine pyrimethamine) 
resistance, both of which have caused major loss of life in Africa," he said in 
reference to earlier generation anti-malarial drugs.
"If the same thing happens again, the spread of a resistant parasite from Asia 
to Africa, that will have devastating consequences for malaria control," he said.
Prof Brian Greenwood, Professor of Tropical Medicine at the London School of 
Hygiene and Tropical Medicine, described the findings as a matter for concern, 
even though treatment still worked if a full course of artemisinin combination 
therapy (ACT) was taken.
"There is currently no need for panic but it would be serious if these partially 
resistant parasites reached Africa where great gains in malaria control are 
currently being made using ACTs and insecticide-treated bed nets," he said.
Health systems
Cambodia has long been a laboratory for malaria investigators and a nursery of 
anti-malaria drug resistance.

Alongside a weak public health system and poorly-controlled drug use, there are 
many fake drugs, produced by international criminals.
These fakes often contain a small amount of the real drug to fool tests, which 
can also help to fuel resistance.
Those working to control malaria are calling for urgent action to contain this 
emerging resistance.
If it strengthens and spreads, they warn, many millions of lives will be at 
risk. About half the world's population faces exposure to the disease.