Health experts were alarmed to find a strain of malaria in western Cambodia that showed resistance to artemisinin, a key drug for fighting the disease. Concerned this could cause a global health crisis, the Cambodian government and international health agencies have spent the past two years fighting the disease ? and are having good results.
Malaria kills around one million people each year, mostly in Africa.
So there was significant concern three years ago when a strain of falciparum malaria in western Cambodia was found to have developed some resistance to artemisinin.
The World Health Organization says artemisinin-based drugs are the most effective malaria treatment. Resistance means that patients with this particular strain take longer to recover.
And the resistance can strengthen and eventually make artemisinin useless against that particular strain.
For the past two years the Cambodian government and partners like the WHO have spent millions of dollars tackling the problem in an area covering about five percent of Cambodian territory, near the western town of Pailin.
The effort included providing more than half a million mosquito nets, educating people on how to avoid malaria, spraying for mosquitoes, and combating fake drugs.
On Tuesday, malaria experts from Cambodia and the WHO said early results are encouraging, and few people are testing positive for the resistant strain.
"We don't really have expectations, but it's phenomenally low - we feel it's very, very low," said Dr. Steven Bjorge, the WHO malaria specialist in Phnom Penh. "It looks like we are having success."
Bjorge, however, warns the battle is far from won. If vigilance is relaxed, the resistant strain could easily spread.
Dr. Nguon Sokomar heads the team at the National Center for Malaria Control that is testing villagers around Pailin.
Team members tested 2,782 villagers in seven of the most infected villages. Just two tested positive for falciparum, a result he says is very encouraging. The number of other malaria cases was also down sharply, with just a few dozen cases recorded.
Nguon says they will test 13 more villages in the coming months.
"We expect that the positivity rate for the following villages will be as well low," said Dr. Nguon Sokomar.
Other teams will roll out the prevention effort across the country in a five-year project costing $102 million, donated by the Global Fund.
Officials hope the program will cut Cambodia's malaria death rate from 270 last year to zero in a decade.