Liaw Wy-Cin, Straits Times 29 Aug 09;
SCIENTISTS in Singapore have come up with a better, faster and cheaper way of studying why some malaria parasites are becoming resistant to even the best drugs available.
They have created a fluorescent chemical compound that adheres or tacks itself onto malaria drugs.
If malaria parasite cells found in a patient's blood respond to the drug - that is, absorb it - the inside of the cell lights up a fluorescent blue.
But if the parasite cell is resistant to the drug, the inside of the cell does not change colour.
This way, scientists can study how parasites resist the effect of conventional malaria drugs, a growing problem in South-east Asia.
The National University of Singapore (NUS) team is now in a global race to be the first among several research groups to get their fluorescent tags out in the market.
The scientists say the tag can also be used to study the behaviour of drugs for other diseases such as cancer and HIV infection.
Current methods of studying drug-resistant malaria parasites are laborious and expensive, using radioactive substances, said malaria researcher Laurent Renia, from the Singapore Immunology Network, part of the Agency for Science, Technology and Research here.
Current methods take some 48 hours, said a member of the NUS team, microbiologist Kevin Tan.
With the fluorescent compound, the process is reduced to under 10 hours, because it does away with some of the steps, said Dr Tan.
Malaria patients are generally not tested to see which drugs they might be resistant to, as the process is long and complicated and drugs need to be administered quickly.
But blood from infected patients is later analysed by scientists trying to solve the puzzle of why malaria parasites are becoming increasingly drug-resistant.
In some south-eastern provinces of Indonesia, up to 60 per cent of relapsing malaria patients no longer respond to first-line treatment drugs such as chloroquine, said Dr Renia.
Singapore has been declared malaria-free since 1982, although it still sees between 100 and 300 cases a year, largely people contracting the disease overseas.
But in 2006 and this year, local outbreaks of about 15 and 30 cases respectively have occurred.
Researchers here said chloroquine and other drugs remain effective against the predominant strain of malaria in Singapore.
So for now, the NUS chemical is just for research use.
But with more research and development, doctors might be able to use it for patients, said another member of the team, chemist Martin Lear.
This may help doctors prescribe the right drug to the patients, depending on which parasite is present in their blood, said infectious diseases doctor Kang Mei Ling from the Singapore General Hospital.
Said Dr Kang: 'Currently, we rely on the patients' travel history to predict if they might have a resistant form of the malaria parasite and, therefore, which drugs to give them.
'For example, if they were in Central America or parts of the Middle East, chloroquine is still effective.
'If they were in parts of Thailand or Myanmar, where parasites are known to be resistant to chloroquine and some other drugs, we will give them an artemisinin combination.
'How we know there is drug resistance is when we see the patient responding poorly to the treatment, then we will have to give another drug or combination of drugs.'
It is hoped the new fluorescent tag will help get the most effective drug to the patients more quickly.
Current methods of studying drug-resistant malaria parasites are laborious and expensive, using radioactive substances... With the fluorescent compound, the process is reduced to under 10 hours.
