This week, we report on a new warning about the worldwide problem of counterfeit medicines. Scientists warn of a growing industry that is producing illegal copies of the anti-malaria drug artesunate. They say these counterfeits are spreading quickly through mainland Southeast Asia.

Counterfeit drugs are sold under the names of real medicines. They often contain no active substance, or not enough to work.

Paul Newton of the University of Oxford in England led an investigation. The researchers tested artesunate tablets that were used to treat a man at a hospital in eastern Burma last year. Artesunate is normally effective, but the twenty-three-year-old man died from common malaria.

The fake tablets were sold as a real product made by Guilin Pharmaceutical of China. The scientists discovered that the tablets contained only ten milligrams of artesunate. The real product contains fifty milligrams.

The hospital had bought a large supply of the drug. It was all fake.

The researchers say there are now at least twelve different kinds of counterfeit artesunate. They say that in Southeast Asia, between forty and fifty percent of drugs identified as artesunate may contain no active substance.

The report expresses concern that Africa could be next. The researchers say the high cost of real artesunate and the shortage of it in Africa create conditions for the spread of fake drugs. Fake artesunate was found in Cameroon in two thousand five. They say the problem may already be widespread.

The World Health Organization estimates that each year almost one million people die from malaria. Most are young children in Africa south of the Sahara.

One of the scientists who did the study is working to develop tests that could identify counterfeit anti-malaria drugs within seconds. Facundo Fernandez is a researcher at the Georgia Institute of Technology. Current methods take two hours.

Paul Newton and his team say the counterfeit drug trade is not just criminal, some might call it murder.

Their report appears in the June publication of PLoS Medicine. PLoS is the Public Library of Science. This non-profit organization publishes scientific journals that anyone can read free of charge on the Internet. The Web site is p-l-o-s dot o-r-g -- again, p-l-o-s dot org (plos.org).

This VOA Special English Development Report was written by Jill Moss. Read and listen to our reports at WWW.51VOA.COM. I'm Steve Ember.