OBJECTIVETo understand the risks and associated factors of HIV transmission by sharing syringes among HIV-positive drug users.

METHODThe survey was conducted among HIV-positive injecting drug users (IDUs-HIV+) who received HIV counseling, testing and treatment in Changsha city Infectious Disease Hospital and Hengyang city No.3 People's Hospital from July 2012 to May 2013 to understand their socio-demographic characteristics, HIV prevalence and syringe sharing. A total of 503 IDUs-HIV+ were involved in and provided the contact list of 2 460 drug users who had the syringe sharing experience over one month with IDUs-HIV+. 420 IDUs-HIV+ among 503 were defined as infection sources due to sharing syringe with at least one drug user. Among them, 234 HIV-negative persons were in control group, and 186 HIV-positive were in cased group. A total of 1 220 drug users were followed up among 2 460 and defined as vulnerable population. The HIV transmission rate was calculated based on the HIV prevalence among vulnerable population. Based on the result of HIV transmission to vulnerable population from 420 infection sources, case-control study and the multivariate logistic regression analysis were adopted to explore the associated factors of HIV transmission among IDUs-HIV+.

RESULTSAs the sources of HIV transmission, 420 IDUs-HIV+ had an average duration of (4.5 ± 1.2) years for drug use. As a susceptible population, 1 220 drug users sharing syringes with the 420 IDUs-HIV+ had an average duration of (1.1 ± 0.5) years for drug use. There were 238 HIV-positive persons among 1 220 vulnerable drug users, with a transmission rate of 0.57. In the case-control study, the proportion of male subjects was 87.1% (162/186) in the case group, which was higher than that in the control group (77.8%, 182/234). The proportion of subjects who received support after knowing their HIV infection status was 51.1% (95/186) in the case group, which was lower than that in the control group (79.5%, 186/234). The proportion of subjects sharing syringes every time of using drugs was 47.8% (89/186) in the case group, which was higher than that in the control group (36.8%, 86/234). The proportion of subjects having AIDS awareness was 21.0% (39/186) in the case group, which was lower than that in the control group (64.5%, 151/234); the proportion of subjects having close contact with HIV-positive persons for more than 106 days was 60.2% (112/186) in the case group, which was higher than that in the control group (31.6%, 74/234). The proportion of subjects maintaining the original drug use method after being infected with HIV was 50.5% (94/186) in the case group, which was higher than that in the control group (16.7%, 39/234) (all P values < 0.05). The multivariate logistic regression analysis was carried out to analyse high correlate factors of HIV transmission by sources of transmission, and the AIDS awareness, duration of contact between sources of transmission and vulnerable population, access to support following confirmed HIV infection were protective factors, OR (95% CI) values were 0.155 (0.104-0.262), 0.170 (0.106-0.253), and 0.306 (0.189-0.450), respectively; while the frequency of syringe sharing and continuous drug use after being infected with HIV were risk factors, and the OR (95% CI) values were 3.06 (1.77-5.29), and 3.54 (2.16-5.80), respectively.

CONCLUSIONHIV transmission by IDUs-HIV+ might be contained by raising AIDS awareness, providing comprehensive psychological support, conducting needle exchange and methadone maintenance treatment and reducing syringe sharing.