There's concern once again that the fight against malaria may be losing some traction. Scientists say a new and effective anti-malaria drug has started to show signs of resistance in Africa, where the disease is endemic, claiming upwards of a million lives each year. Public health officials worry about misuse of the drug, artemisinin and what that could mean for the treatment of malaria.
Roughly 50 years ago, chloroquine and other quinine-derived drugs were extremely effective in treating malaria, a disease spread by the bite of mosquitos infected with the parasite, Plasmodium Falciparum.
The illness causes extremely high fevers, bouts of chills, jaundice and severe anemia. Young children who contract malaria often die.
Chloroquine and mefloquine have since become ineffective against the parasite because of the misuse of chloroquine, but in the last decade or so, an effective, new drug, called artemisinin, has come into use.
The World Health Organization (WHO) has urged countries to use artemisinin in combination with other anti-malarials so it, too, does not lose its effectiveness.
But the warning isn't being heeded, and a study published this week in the journal the Lancet found the first evidence of resistance to artemisinin in two African countries where the drug is readily available, according to researcher Ramon Jambou of the Pasteur Institute.
"In Senegal and in French Guiana, artemisinin was not used by the ministry. It just used by everyone but on markets and so on," he explained.
Dr. Jambou and colleagues took blood samples from 530 patients in French Guiana, Senegal and Cambodia treated with different artemisinin-derived drugs. The samples were tested to measure the parasite's sensitivity to artemisinin.
The researchers found no resistance in samples taken from Cambodia, which carefully controls the use of the drug. The parasite was less sensitive to the drug in Senegal, where artemisinin is somewhat restricted. Resistance to the drug was greatest in French Guiana, where it is readily available.
Dr. Jambou, who led the study, says the problem is being caused by using artemisinin-derived drugs alone.
"Now, the treatments with combination[s] are OK," he explained. "But I think we are just at the beginning of the problem and it's something that we have to take care carefully to first show the appearance of resistance and [the] second time, to use carefully the treatment with combination [therapy] and not alone."
Experts say the reason why combining drugs works is that it's harder for the malaria parasite to alter its genetic make-up to dodge two drugs instead of one.
Patrick Duffy of Seattle's Malaria Antigen Discovery Program in Washington wrote a commentary in the Lancet.
Dr. Duffy says the study offers a cautionary tale about the use, and misuse, of artemisinin.
"They're now being rolled out all across Africa. And if they're used indiscriminately, and are not controlled in their use, people are much less likely to take them as they are prescribed. And therefore that increases the likelihood that resistance could develop to them," Dr. Duffy added.
Dr. Duffy says it's important to maintain careful surveillance in countries where artemisinin-derived drugs are being used, making sure they are distributed and used responsibly.