Voice of America (Washington, DC)

Africa: Rapid Blood Test Reveals Growing Resistance to Malaria

Scientists have developed a simple, rapid blood test to determine the malaria parasite's resistance to artemisinin, currently the most effective drug available to treat the mosquito-borne infection.

Unfortunately, the drug is becoming less effective. But researchers are hoping the test will eventually help patients with drug-resistant malaria.

More than 200 million people are infected with malaria each year, with a death toll as high as 1.2 million. Most of the infections occur in sub-Saharan Africa.

While artemisinin-containing drugs are currently the most effective weapon in the fight against malaria, the parasite that causes it is beginning to develop resistance.

Rick Fairhurst, a clinical investigator with the U.S. National Institutes of Health in Maryland, says most malaria patients used to be cured with three doses of artemisinin taken over a three-day period.

"And now what we are seeing is that patients, like for example in Pursat where I work, we have about 60 percent of people [that] still have parasites at 72 hours, which suggests that these parasites could persist in the patient, which results in them not being cured," said Fairhurst.

Pursat province is an area in western Cambodia.

Fairhurst, along with a team of Cambodian and French researchers, developed a rapid blood test that measures how quickly the malaria parasites in blood samples were killed or weakened by the active ingredient in artemisinin.

The parasites' survival was measured 72 hours after exposure to the artemisinin. If the parasite was still active at that point, the researchers determined that it was unlikely to respond to the drug.

Researchers confirmed the finding in patients infected with malaria. Parasites in blood samples taken from people with drug-resistant infections had only a tepid response to artemisinin.

Such a test could help public health officials identify pockets of drug resistance and map its spread.

Fairhurst says the blood test could also be used to follow individuals treated with artemisinin.

"And if eventually we find if parasites are at a certain level of resistance in the laboratory, they have a certain probability of coming back in the patient, we can then say, 'Okay, this person is not likely to [be cured of their infection],' and we can come on top with a second drug," he said.

Fairhurst says there are a couple of newer, more expensive anti-malarial agents that could be used but which experts fear could also eventually become ineffective against the parasite.

An article on the rapid blood test for artemisinin-resistant malaria is published in the journal The Lancet Infectious Diseases.

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