Xiong Rucheng remembers the day he and his colleagues at the Yunnan Public Health Bureau learned that drug addicts near the border with Burma had contracted AIDS.
"No one could believe it," said Xiong, chairman of the bureau's foreign affairs office. "How could China have AIDS?"
In September, they sent the report to officials at the Ministry of Public Health in Beijing, who did not believe it either.
"They said, 'We'll help you clear this up,' " Xiong said, but after testing the 50 samples three times, "they finally believed us."
He said 146 drug addicts out of nearly 6,000 tested had been found to carry the HIV virus.
Previously, only seven Chinese were known to have contracted acquired immune deficiency syndrome, the deadly disease that weakens the body's immune system, making it susceptible to infections.
They either were hemophiliacs infected by contaminated blood products or had contracted AIDS overseas or through homosexual relations with foreigners, according to official reports.
AIDS victims in Yunnan are drug addicts who used contaminated needles.
Chinese health authorities had targeted coastal cities, where contact with foreigners is most common, in their efforts to prevent AIDS from entering China.
"How did they know it would be found in far-off Yunnan, a minority area, where the people are honest and unsophisticated?" Xiong said. "How could such a place have contracted the most frightening disease of the modern age?"
Yunnan is a poor, remote, mountainous province in southwestern China that is home to nearly half the country's minorities.
Nearly all the AIDS victims were found in Ruili, an area on the Burmese frontier that is closed to foreigners. Chinese visitors describe it as a wild, dangerous place full of traders and smugglers from Nepal, Pakistan, Laos and Burma.
In Ruili, drug users prefer injecting heroin to smoking opium, Xiong said.
He said 80% of the AIDS carriers were of the Dai minority, only one was a woman, and none had begun showing symptoms of AIDS.
All continue to lead normal lives and have not been told they have AIDS, Xiong said.