Recently, the World Health Organization (WHO) announced that the emergence of parasites, along the Thai-Cambodia border, that are resistant to the medicine artemisinin  could seriously undermine global malaria control. 

The recent shift from drugs that were failing to the highly effective artemisinin-based combination therapies allowed great progress in fighting malaria, one of the world's major killers.

More than one million people die of malaria each year, mostly in Africa.

The disease poses a risk to half of the world's population, according to the World Health Organization

Now, along the Thai-Cambodian border, researchers have discovered a malaria parasite that is resistant to the most effective anti-malaria medicine.  

Colonel Gray Heppner is a key researcher on malaria and Deputy Commander at the Walter Reed Research Institute in Maryland. 

He says if drug resistance spreads, the number of yearly deaths could double.

"And it's not just the death toll, it is the number of people who are chronically ill because we can't cure them," Heppner said. "So if you can imagine all the people that are chronically ill with malaria today. And some estimates are that there are a half a billion people that have a recognized episode of malaria every year. And if you think about doubling this, well it puts an incredible burden in a society."

The recent news in a report by U.S. Army researcher Mark Fukuda, published in  the New England Journal of Medicine, shows that some malaria parasites are resistant to artemisinin. 

"The artemisinins are the most rapidly effective medicine that has ever been invented for malaria," he said.

"Artemisia" is a plant.  Its derivatives are known as artemisinins.  The Chinese have used the plant for centuries against fever.

But a few decades ago, when malaria parasites became immune to chloroquine and other medications, artemisinin became the world's great hope.  

In the last decade, malaria control programs have also included insecticide-treated bed nets - to shield against mosquitos that carry the parasites.  The nets and artemisinins have helped lower infection rates in many countries, mostly in Africa.

For the moment, there is no replacement for artemisinin-based drugs.    

The Walter Reed Institute has been working to develop a vaccine against malaria as well as new medicines.   

Colonel Peter Weina, who specializes in tropical diseases, and specifically malaria, led the U.S. Army's effort to develop a drug against the most severe form of malaria. "Intravenous Artesunate" has not yet received final approval, but is now being use in certain cases.   

"We have our formulation available on compassionate use here in the U.S. and recently in Canada.  We have donated several hundred vials to clinical trials that are being done in Africa with some of our partner groups," Dr. Weina said.

But this drug is also derived from artemisinin.  

"There was an assumption and there was a hope and there was a prayer that resistance to artemisinin would never happen," he said.

Research to find new medications against malaria continue.

"Out of every 5,000 compounds that show promise," Dr. Weina said. "Only one of them statistically will make it to being a drug that is useful."

The World Health Organization and the Bill and Melinda Gates Foundation have launched a multi-million dollar campaign to control the spread of the artemisinin resistant parasite.

But as Dr. Weina says, malaria is a disease of poverty. It thrives in areas lacking hygiene and resources.  And it will be with us for years.