The lack of epidemiological link between the HIV type 1 infections in Hong Kong and Mainland China.

Blood samples were collected from 139 newly reported HIV-1 infections in Hong Kong over a 3-year period between 1999 and 2001, representing 22.8% of all reported cases. A majority of the patients were male (85.6%), Chinese (74%), and adult (97.1%) and acquired HIV-1 through sexual transmission (88.2%). The B and CRF01_AE were the major subtypes detected--49.6% and 44.6%, respectively. Over time, the frequency of CRF01_AE subtype increased, the B subtype decreased, and new subtypes of C (4) 2.8%, B' (1) 0.7%, and CRF07_BC (3) 2.2% emerged. The CRF01_AE subtype was commoner in female, Chinese, heterosexuals, and injection drug users whereas B subtype was commoner in male, white, and people with homosexual/bisexual contacts. There was no common source of infection from the analysis except a discernible cluster of Vietnamese injection drug users with the CRF01_AE subtype. The molecular findings did not suggest an epidemiological link between HIV infection in Hong Kong and Mainland China. Hong Kong's longstanding and extensive methadone treatment network may have contributed to the phenomenon.