Salas says evidence also suggests that HIV started spreading in Africa ahead of some other regions.
Signs increasingly warn that massive HIV epidemics also threaten China, India, and other Asian nations. According to the new WHO report, 10 percent of the world's HIV-positive population already resides in India. AIDS is the leading cause of death in people under the age of 50 in Thailand, according to Salas, and the disease threatens to overrun Cambodia's health care system.
The Chinese government says that 850,000 people in the nation have contracted HIV, but other estimates are much higher, said Tom Hurley, of the Geneva-based Global Fund to Fight AIDS, Tuberculosis, and Malaria.
Hurley says stigma and discrimination are some of the factors contributing to the spread of the disease in Asia. "People in China, for example, are terribly stigmatized because of misconceptions about how the disease is spread," he said. "Many believe HIV can be passed through casual contact." The misconception dissuades sufferers from seeking tests or treatment.
Hurley says ignorance about the disease poses a big problem in many Asian countries and is further exacerbated by the unequal status of women.
In India, for example, literacy rates are much lower for women than men, and women have less access to education and information that might protect them against contracting the virus.
Cultural phenomena such as Southeast Asia's enormous commercial sex industry are also possible reasons behind the rapid spread of AIDS.
Salas, of the International AIDS Alliance, said many Asian countries have denied the existence of the AIDS epidemic for a long time. "When you are in denial, then it is difficult to formulate a coherent response to anything," Salas said.
Piot and co-authors of the new WHO HIV/AIDS report write that there are several major challenges in the battle against HIV and AIDS that should be addressed during next month's International AIDS Conference in Bangkok.
One challenge will be providing the funding, infrastructure, and human resources to prevent and treat the disease. (In their report, the authors argue that as drug prices fall, the lack of health workers could be a major factor holding up treatment and intervention.)
The authors also write that some countries have not been quick enough to recognize the scale of their epidemics. Also, other countries have failed to stop local infections from spreading into national ones, the authors say.
The report says that one major challenge to keeping the Asian epidemics under control will be to prepare governments. The report states: "At the heart of every national success story against HIV/AIDS is strong and visible national commitment and leadership."
Piot and his co-authors point to the examples of Cambodia and Thailand, which have already contended with severe epidemics. Strong government programs to educate people and prevent the spread of the disease in those countries have now stabilized the rates of infection.
Thailand's national "100 Percent Condom Use" program, for example, has caused a significant drop in HIV rates. The effort makes condoms available to all sex workers and encourages condom use.
The authors write: "Ultimately, the most critical element of a sustained global response to AIDS is the willingness and ability of nations to take ownership of the problem."
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