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New Malaria Drug May Help Stem Disease's Growing Resistance - 2004-08-19

Malaria, which afflicts an estimated 40 percent of the world's population, is becoming more of a global problem. In an article in this week's journal Science, researchers report creeping resistance to drugs used to fight the disease from Asia to Africa, where malaria is the number one killer of young children. But help may be on the way. In another journal, Nature, scientists say they have developed what appears to be a cheap, effective synthetic drug to combat the mosquito-borne illness.

Malaria strikes 300 to 500 million people every year, and kills one million individuals, most of them children who die of the lethal fevers. Most of the victims live in sub-Saharan Africa, where the disease burden is greatest.

The main reason is that cheap, old-line drugs are now failing to kill the parasite in up to 90 percent of cases, as it mutates to evade the effect of the medicines.

That includes chloroquine and mefloquine, which have been used for years to treat malaria before the parasite became resistant to them. A newer anti-malarial drug, paramethynine, has met with widespread resistance throughout Asia.

As in Asia, researchers had assumed small treatment failures of paramethynine in Africa were confined to the continent, but a genetic analysis concludes otherwise. It appears resistant malaria parasites turning up in Africa had made their way to the sub-Saharan region from Asia. Callie Roper, a researcher with the London School of Hygiene and Tropical Medicine, says "it's showing that the resistance genes are highly mobile and that resistance is a global problem. It was thought previously that resistance to paramethynine had arisen quite a number of times in Africa itself, and now it appears that it didn't. A highly resistant form of the gene was actually introduced outside."

Dr. Roper and colleagues say some travel restrictions may be necessary. "To prevent the importation of resistant parasites from areas where resistance has arisen already," she says.

Dr. Roper adds new drugs are urgently needed to further contain the spread of drug resistant malaria.

Malaria drug researchers are universally pinning hopes on compounds derived from artemisinin, an ancient Chinese herb that has proven to be highly effective in treating malaria. The problem is the herb is expensive to process, putting it out of reach of many families and international aid organizations.

But researchers announced this week that they have developed what they're calling a synthetic artemisinin compound that would cost pennies to make.

Carl Craft is chief scientist of Medicines for Malaria Venture in Geneva, which has been developing the anti-malarial agent, which he says is not subject to the same environmental factors as artemisinin grown in the wild. "Well, for one thing you don't have to worry about planting thousands of [hectares] of plants and harvesting them. It can all be done in a chemical plant, where you don't have to worry about rains and floods and bad weather," he says.

Known as OZ, Dr. Craft says the drug has a similar mode-of-action as artemisinin

He says the new drug would be significantly cheaper than the artemisinin herb. "Which will be combined with another drug to make sure we don't get resistance. The amount of the cost of this drug for that combination would be about 20 cents compared to $1 or more for artemisinin compound. So, significantly better."

Medicines for Malaria Venture of India is conducting human safety trials in Britain. The company plans to test the drug's effectiveness beginning next January.