OBJECTIVETo investigate the factors of the human immunodeficiency virus (HIV) associated with sexual-transmission in central China.

METHODS(1) Cross-sectional study: couples that one was HIV positive were selected in Henan and Hebei province of China. The couples must be 20 - 50 years old with normal function on sexual intercourse. Cordant couples that subsequently infected partners were at risk of infection solely through sexual contact with the HIV-seropositive partner and the discordant couples that the seronegative partners were at risk of infection solely through sexual contact with the HIV-seropositive partner, were selected. Plasma viral load, CD4 cell count were tested. (2) Case-control study was used to compare 7 sexual transmitted cases and 56 nontransmitted controls with respect to the frequency of sexual intercourse, plasma viral load and CD4 cell count.

RESULTS(1) A total of 87 couples that at least one partner was HIV positive were recruited include 56 discordant couples and 7 cordant couples with whom sexual transmission had happened. The rate of sexual transmission was 11.1% among those at the risk of sexual transmission. (2) Of the discordant couples, male positive rate 25%, female positive was 75%. (3) The risk for transmission was higher in those couples with the frequency of unprotected vaginal sexual intercourse (> or = 4 times per month) than the reference group (< 4 times per month) (Fisher's exact test, P = 0.047, OR = 8.0). Median plasma viral load was significantly higher in the antecedent infected partners of cordant couples than the positive partner of discordant couples (378,285.71 vs 136,578.57 copies/ml, t = 3.591, P < 0.01). The odds ratio was 22.0 for plasma viral load > or = 100,000 copies/ml compared with the reference group of < 100 000 copies/ml (Fisher's exact test, P = 0.016). The CD4 cell count and CD4/CD8 of the transmitted group were significantly lower than that of the nontransmitted (t = 2.767, P < 0.05; t = 6.06, P < 0.05).

CONCLUSIONSThe frequencies of heterosexual-transmission in central China were relatively low. The risk of heterosexual transmission was related to the frequency of sexual intercourse. Higher plasma viral load and lower CD4 count was strongly correlated with high risk of heterosexual transmission.