HONG KONG (Reuters) - HIV infections jumped 8-fold over the past few years in parts of China among gay and bisexual men, according to new data from southern China.
Published in Nature, the study found that the proportion of HIV-positive women of child-bearing age doubled in the past 10 years and researchers warned the disease was moving from high-risk communities into the wider population.
There were an estimated 700,000 HIV/AIDS cases in China as of October 2007, up 8 percent compared to 2006, it said. Some 38 percent of cases were attributed to heterosexual contact, more than triple the 11 percent in 2005.
Cases among gay and bisexual men jumped to 3.3 percent in 2007 from 0.4 percent in 2005.
"HIV/AIDS is spreading beyond the high risk populations, largely due to increased transmission through sexual contact. It implies that HIV/AIDS is not only a disease that affects high risk population, but the general population alike," professor Zhang Linqi, director of the AIDS Research Center in Beijing, wrote in an email reply to questions from Reuters.
The study focused on the epidemic in China's southwestern Yunnan province, which has a long history of opium and heroin trade and where infections are highest among intravenous drug users. Yunnan borders Laos, Myanmar and Vietnam.
The researchers studied 3.2 million blood samples tested between 1989 and 2006 in Yunnan.
While the proportion of intravenous drug users fell from 100 percent in 1989 to 40 percent in 2006, heterosexual transmission rose markedly, accounting for 37.5 percent of infections in 2006.
Women now make up 35 percent of those infected in Yunnan, from 7.1 percent before 1996.
"As 90 percent of these women are of child-bearing age (age 15 to 44), this is likely to translate into more vertical transmission from mother to child," they wrote in the article.
Such changing demographics have resulted in changes in HIV strains now circulating in Yunnan. They can be classified into two main groups, one circulating in Thailand and Myanmar and the other in France and the United States.
"It makes treatment and vaccine development even more challenging," Zhang wrote, adding that prevention strategies that have proven successful should be scaled up.
(Editing by Jerry Norton)