Parasites are developing resistance to one of the most important anti-malaria drugs, according to experts.Artimisinin has been highly effective, particularly in places where resistance to other drugs has developed.But now some patients along Cambodia's border with Thailand are taking longer to respond to the treatment.Experts on the disease are meeting village health workers in Cambodia's capital, Phnom Penh, to discuss ways to stop drug-resistant malaria spreading.Malaria Consortium technical director Dr Sylvia Meek says it must be eliminated before it spreads."There is a lot of population movement - people coming for instance from Nigeria to Asia - and it's growing and growing," she said."It would only take a few people carrying the resistant parasites travelling one way or the other to actually get the parasites in."And once they're in they're likely to spread quite fast."Source: BBC