http://news.bbc.co.uk/1/hi/world/asia-pacific/8073118.stm

International scientists say they have found the first evidence of resistance to the world's most effective drug for treating malaria.

They say the trend in western Cambodia has to be urgently contained because full-blown resistance would be a global health catastrophe.

Drugs are taking longer to clear blood of malaria parasites than before.

This is an early warning sign of emerging resistance to a disease which kills a million people every year.

Until now the most effective drug cleared all malaria parasites from the blood within two or three days but in recent trials this took up to four or five days.

Two teams of scientists, working on separate clinical trials, have reported seeing the disturbing evidence that the drugs are becoming much less effective.

Unfortunately (but not unexpectedly) there are strong indications that the restitance is becoming more widespread.

Emergence of artemisinin-resistant malaria on the western border of Thailand: a longitudinal study

Background

Artemisinin-resistant falciparum malaria has arisen in western Cambodia. A concerted international effort is underway to contain artemisinin-resistant Plasmodium falciparum, but containment strategies are dependent on whether resistance has emerged elsewhere. We aimed to establish whether artemisinin resistance has spread or emerged on the Thailand—Myanmar (Burma) border.

...

Interpretation

Genetically determined artemisinin resistance in P falciparum emerged along the Thailand—Myanmar border at least 8 years ago and has since increased substantially. At this rate of increase, resistance will reach rates reported in western Cambodia in 2—6 years.