BEIJING: The World Health Organization issued a call to action to China Monday over HIV/AIDS as government figures said nearly half a million people are living with the disease or its precursor, with hundreds of thousands more thought to be undiagnosed. Sexual contact is the most common means of transmission in China, followed by mother-to-baby transmission and drug needle sharing, the Family Planning Commission said. But now, sexual transmission accounts for more than 90 percent of infections, the official Xinhua news agency said, citing the Chinese Center for Disease Control and Prevention (CCDCP). Gay men accounted for 25 percent of new HIV cases in the first eight months of this year, according to the CCDCP, up from 19 percent in 2012. The figure represents an increase from September 2013, when 434,000 people in China were known to be living with HIV/AIDS.