An inexpensive drug called chloroquine may again be effective in treating malaria because years of disuse have boosted its potency against the often fatal mosquito-borne disease, a new study shows.
Chloroquine had been the mainstay of malaria therapy until the disease developed a resistance to it and health officials stopped using it widely more than a decade ago.
Now a study, published in this week's New England Journal of Medicine, shows the drug is newly potent again, perhaps because the strains of the disease that were once immune to it have more trouble surviving.
Researchers who tested children found that the drug packed a new punch, working 99 percent of the time. A replacement treatment, sulfadoxine and pyrimethamine, was effective in only 21 percent of the cases.
Although there had been some early indications that chloroquine was effective again, "we were still amazed at how quickly these children got better," said Christopher Plowe, a researcher at the University of Maryland who helped conduct the study.
The drug is simple to administer, requires only a few doses, has few side effects, and costs about 10 cents per treatment, far less than any other therapy.
Officials in Malawi stopped using it in 1993 when it was effective in less than 50 percent of patients.
"If chloroquine can be withdrawn from use throughout Africa as effectively as it was withdrawn in Malawi, it may be possible to include it as one component of a new generation of combination therapy in the not-so-distant future," Miriam Laufer of the University of Maryland School of Medicine and the leader of the research team told Reuters.
Malaria kills over 5,000 people a day, 90 percent of whom are children under the age of 5 and living in Africa.
The researchers said the drug's new potency resulted largely from the fact that it was not prescribed for a long time. Chloroquine "needs to leave before it can come back," said Nicholas White of Mahidol University in Bangkok, in a commentary in the New England Journal of Medicine.
Plowe said "It would be worthwhile to explore the possibility of rotating drugs for malaria as well as other infections that have become resistant to important drugs" to see if that restores their effectiveness.