The NY Times reports that in a sample of malaria medicines from Southeast Asia that were tested, 53 percent were found to be fake. The fake drugs are manufactured in China. The article reports that the sophisticated packaging and chemical make up of these drugs renders them almost totally indistinguishable from the genuine product. Because some fake drugs contain aspirin, patients are deceived; they may feel as if the fake drug is "working."
According to one source, the distribution of the deadly fakes mirrors the old heroin distribution networks. That would put Northern Burma at the epicentre of distribution, where contacts with Thai distributors move the drug onwards. When I visited the Burmese border town of Tachileik, I noted that a dozen people tried to sell me viagra. Based on the Times report, it would seem that the Viagra they were peddling was almost certainly fake.