[1] Univ N Carolina, Sch Med, Dept Med, Chapel Hill, NC 27515 USA
[2] Guangdong Prov STD Control Ctr, UNC Project China Off, Guangzhou, Guangdong, Peoples R China
[3] Sun Yat Sen Univ, Sch Sociol & Anthropol, Guangzhou 510275, Guangdong, Peoples R China
[4] Sun Yat Sen Univ, Zhongshan Sch Med, Ctr Med Humanities, Guangzhou 510275, Guangdong, Peoples R China
[5] Stanford Univ, Sch Med, Palo Alto, CA 94304 USA
[6] Univ Otago, Dunedin, New Zealand
[7] Fudan Univ, Sch Med, Shanghai 200433, Peoples R China
[8] Harvard Univ, Harvard Med Sch, Boston, MA 02115 USA
[9] Sun Yat Sen Univ, Affiliated Hosp 6, Guangzhou 510275, Guangdong, Peoples R China
[10] Univ Hong Kong, Ap Lei Chau, Hong Kong, Peoples R China
[11] Univ Hong Kong Shenzhen Hosp, Shenzhen, Guangdong, Peoples R China
[12] Sun Yat Sen Univ, Guangdong Inst Gastroenterol, Guangzhou 510275, Guangdong, Peoples R China
[13] Harvard Univ, Harvard Asia Ctr, Cambridge, MA 02138 USA