抗药性疟疾的威胁疾病控制

A team of researchers from the United States and Thailand says the growing number of cases of drug-resistant malaria being reported in Thailand and neighboring countries threatens the worldwide campaign to control and eliminate the mosquito-borne disease. The malaria parasite in the region is becoming resistant to the first-line malaria therapy - artemisinin combination treatment - and experts say there is a real danger of the resistant strain moving to Africa, where malaria is widespread.

“The biggest fear is the resistance will spread across Southeast Asia and then spill over into Africa, where the vast majority of the 700,000 deaths a year [from malaria] occur. Historically, we have seen that when resistance to chloroquine [another anti-malaria drug] spread, there was an increase in mortality due to malaria. This is a very, very urgent situation,” said Tim Anderson, of the Texas Biomedical Research Institute, who spoke to us via Skype.

Anderson was part of the team that found evidence of growing resistance to artemesinin therapy for malaria in the border regions of Thailand and Burma, which they fear can spread westward across south east Asia and into Africa. The researchers are calling for immediate steps to control the spread of the resistant malaria parasite.

The number of malaria deaths dropped in the last few years because of the artemisinin combination treatment, and Anderson predicts that mortality figures will rebound if the drug loses its efficacy.

“We are seeing that the drug kills the parasite 100-fold less well than it used to. That doesn’t mean that the parasites are not killed, so we can still cure patients. But the concern is that the number of patients who are NOT cured will rise. We currently estimate that about 30 percent of the patients are not cured with artemisinin,” said Anderson.

“I have to say that I am not actually all that surprised. Every time we have developed a new drug, the parasite has figured out a way to get around it,” said Dr. David Kaslow, the director of the PATH Malaria Vaccine Initiative - an international noNPRofit organization committed to developing a malaria vaccine.

“The good news is that the first-ever malaria vaccine is on the horizon,” said Kaslow.

The malaria vaccine could be available by 2015, Kaslow said. But it will be just one more weapon against malaria, and the problem of resistance to artemisinin is real.

“It is a piece of a larger control and - hopefully, some day - elimination and eradication program. We have to use a variety of tools - [including] bed nets, indoor residual spraying, and preventive therapy,” said Kaslow.

Experts say drug-resistant strains of malaria likely will continue to emerge. The solution, they believe, is to support the development of new drugs and new therapies to fight the disease.