Trends in HIV transmission according to differences in numbers of sexual partnerships among men who have sex with men in China

The development of the HIV epidemic in China can be divided into four distinct phases [1-3]. The first phase (1985-1988) was marked by China's first diagnosis of an AIDS case in Beijing in 1985, followed by 22 cases in seven other provinces, including 18 foreigners and 4 Chinese residents, and all were infected by HIV-contaminated blood products [4, 5]. During the second phase (1989-1993), 146 HIV/AIDS cases were diagnosed among injecting drug users (IDUs) in Yunnan. The first HIV case among MSM (men who have sex with men) case was also diagnosed in Beijing in 1989, but HIV transmission among MSM remained low [6-8]. The third phase (1994-2000) covered the large expansion in the numbers of infections among IDU and the epidemic started to spread from Yunnan to other Chinese provinces. By the mid-1990s it was clear that the epidemic had severely afflicted the population of IDUs, and by the late 1990s HIV infections had been reported in all 31 provinces, autonomous regions, and municipalities, with drug users accounting for 60-70% of reported infections [9]. The fourth phase (2001-present) was marked by a series of events and interventions that responded to HIV on a national level [1, 2]. China released two consecutive 5-year action plans to limit the spread of HIV/AIDS, in 2001 and 2006, respectively [10, 11]. Several national prevention and treatment programs such as China CARES (China Comprehensive AIDS Response) and Four Frees, One Care policy were established in response to the rapid emerging HIV epidemic in China.