Asia is seeing an "epidemic of counterfeits" of life-saving drugs, experts say, and the problem is spreading. Malaria medicines have been particularly hard hit; in a recent sampling in Southeast Asia, 53 percent of the antimalarials bought were fakes.
Bogus antibiotics, tuberculosis drugs, AIDS drugs and even meningitis vaccines have also been found.
Estimates of the deaths caused by fakes run from tens of thousands a year to 200,000 or more. The World Health Organization has estimated that a fifth of the one million annual deaths from malaria would be prevented if all medicines for it were genuine and taken properly.
"The impact on people's lives behind these figures is devastating," said Dr. Howard A. Zucker, the organization's chief of health technology and pharmaceuticals.
Internationally, a prime target of counterfeiters now is artemisinin, the newest miracle cure for malaria, said Dr. Paul N. Newton of Oxford University's Center for Tropical Medicine in Vientiane, Laos.
His team, which found that more than half the malaria drugs it bought in Southeast Asia were counterfeit, discovered 12 fakes being sold as artesunate pills made by Guilin Pharma of China.
A charity working in Myanmar bought 100,000 tablets and discovered that all were worthless.
"They're not being produced in somebody's kitchen," Dr. Newton said. "They're produced on an industrial scale."
China is the source of most of the world's fake drugs, experts say. In December, according to Xinhua, the state news agency, the former chief of China's Food and Drug Administration and two of his top deputies were arrested on charges of taking bribes to approve drugs.
The director, Zheng Xiaoyu, was in office from the agency's creation in 1998 until he was dismissed in 2005 after repeated scandals in which medicines and infant formula his agency had approved killed dozens of Chinese, including children.
"The problem is simply so massive that no amount of enforcement is going to stop it," said David Fernyhough, a counterfeiting expert at the Hong Kong offices of Hill & Associates, a risk-management firm hired by Western companies to foil counterfeiters.
The distribution networks, he said, "mirror the old heroin networks," flowing to Thai distributors with financing and money-laundering arranged in Hong Kong. The penalties are less severe than for heroin.
Daniel C. K. Chow, an Ohio State University law professor and an expert on Chinese counterfeiting, said he believed that the authorities would pursue counterfeiters "ruthlessly" for killing Chinese citizens but be more lax about drugs for export.
"The counterfeiters aren't stupid," he said. "They don't want anyone beating down the door in the middle of the night and dragging them away, so they make drugs for sale outside the country."
A spokesman for the Chinese Embassy in Washington said that he had "no idea" whether most of the world's counterfeits came from China, but that Mr. Zheng's arrest proved China was cracking down. He also said counterfeiters would get the same punishment no matter whom they hurt.
Many of the fake artesunate pills found by Dr. Newton's team were startlingly accurate in appearance — and much more devious in effect than investigators had suspected.
Not only did the pills look correct, as did the cardboard boxes, the blister packing and the foil backing, but investigators found 12 versions of the tiny hologram added to prevent forgery.
In one case, even a secret "X-52" logo visible only under ultraviolet light was present, though in the wrong spot.
Another hologram was forged by hand, Dr. Newton said, by someone who obviously spent hours with a pin and a magnifying glass making tiny dots on a circle of foil to imitate the shimmer.
But the most frightening aspect appeared when the pills were tested. Some contained harmless chalk, starch or flour. But the latest, he said, contained drugs apparently chosen to fool patients into thinking the pills were working.
Some had acetaminophen, which can temporarily lower malarial fevers but does not kill parasites. Some had chloroquine, an old and now nearly useless antimalarial.
One had a sulfa drug that in allergic people could cause a fatal rash.
And some had a little real artemisinin — not enough to cure, but enough to produce a false positive on the common Fast Red dye test for the genuine article.
Those would not merely fool a laboratory, Dr. Newton noted. They could also foster drug-resistant parasites, so if patients were lucky enough to get genuine artemisinin treatment later, they might have already developed an incurable strain and could die anyway.
Such resistant strains could spread from person to person by mosquito and ultimately render the drug ineffective, as already happened with chloroquine and Fansidar, two earlier malaria cures.
"We make no apology for the use of the term 'manslaughter' to describe this criminal lethal trade," Dr. Newton and his co-authors said last year in an article in The Public Library of Science Medicine. "Indeed, some might call it murder."
In the United States, finding counterfeit drugs in pharmacies is very rare, "but we've seen a lot from Internet sellers posing as legitimate pharmacies," said Dr. Ilisa Bernstein, director of pharmacy affairs for the Food and Drug Administration.
Thus far, few counterfeits of life-saving drugs have been found in the United States. Most are drugs used or abused for fun, like Viagra, the painkiller Oxycontin and sleeping pills. Investigators have, however, found fake statins, which could eventually lead to a heart attack, and fake Tamiflu, which could be fatal in a pandemic of lethal flu.
Fake drugs have a long history; the film noir masterpiece "The Third Man," based on a real criminal case, involves adulterated penicillin in post-war Vienna.
And in the 1600s, after conquistadors discovered that South American cinchona bark cured malaria, Europe was flooded with fake bark. "It caused a great loss of confidence in it as a cure," Dr. Newton said. "We're seeing history repeat itself."
The problem with antimalarials is worst in Asia, but is growing rapidly in Africa.
For example, in September, Nigerian authorities found $25,000 worth of counterfeit malaria and blood pressure drugs concealed in a shipment of purses from China.
The temptation for counterfeiters is likely to grow because money to fight malaria is being poured into the third world.
President Bush's $1.2 billion Malaria Initiative avoids the problem by buying directly from Western pharmaceutical companies like Novartis, said Dr. Trenton K. Ruebush II, an adviser to the initiative.
By contrast, the Global Fund to Fight AIDS, Tuberculosis and Malaria gives money directly to poor countries to buy their own drugs, and sends auditors to follow up. But 80 percent of the world's nations, pharmacology experts estimate, lack drug agencies capable of detecting sophisticated counterfeits.
"The countries are supposed to purchase from W.H.O.-qualified manufacturers, but there are places where things can go wrong where we wouldn't necessarily have control," said Dr. Bernard Nahlen, the fund's malariologist. "In some countries, there is, let's say, a certain lethargy about paying attention to these issues. You have to take the government's word for it, and anybody can pull the wool over anybody's eyes."
The Global Fund, which appointed a new director on Feb. 8, is considering adopting central purchasing, a spokesman said.
A global alert system for counterfeit drugs has existed for 16 years, first by fax, and now on the World Health Organization Web site, said Dr. Valerio Reggi, chief of the anticounterfeiting task force created last year by the organization.
"But it isn't used very much," he said. "Regulators are human beings, and it's difficult to identify a benefit for those who report to it."
Dr. Reggi said the task force would try to change that by drawing attention to the problem and getting harsher laws passed. As he pointed out, in many countries, "counterfeiting a T-shirt means 10 years in jail, but counterfeiting a medicine can be a misdemeanor."