Introduction.

Yunnan is one of the provinces hardest hit by HIV epidemic in China, since the first large HIV outbreak occurred in 1989 among injecting drug users (IDUs) in Dehong prefecture [1]–[4]. In Yunnan, the cumulative number of HIV positives reported at the end of October 2011 was 93, 567, including 25, 698 AIDS cases and 14,340 recorded deaths. According to sentinel surveillance data, HIV prevalence mainly concentrated on two high-risk populations: IDUs and female sexual workers (FSWs). 53.2% HIV positive cases were IDUs, and 18.6% were FSWs [5]. Although HIV infection through heterosexual contact has increased steadily from less than 5% in 1996 to up to 20% recently, intravenous drug use is still the dominate transmission mode of HIV [4].

A long history of opium/heroin trade and high prevalence of illicit drugs, majority of which are trafficked from “golden triangle”, have partly accounted for the high prevalence of HIV infection in Yunnan, especially among IDUs [6]. The data showed that HIV in Yunnan has primarily spread through intravenous drug use with a high annual incidence rate of 2.2%–8.0% [7], and the provincial average prevalence among IDUs fluctuated between 21.2% and 27.8% through 2004 [3]. Moreover, the rate of HIV infection among IDUs was reported as high as 74.5% [8]. However, HIV prevalence varies from region to region in Yunnan Province. Sentinel surveillance data in 2004 indicated that HIV prevalence among IDUs was 60.4% in Kaiyuan city, 41% in Yingjiang county, 21.5% in Qujing prefecture, 4.6% in Zhaotong prefecture and 2.9% in Baoshan prefecture [9]. Furthermore, these ratios reported recently still reveal uneven prevalence in different regions. By the end of 2007, in several regions including Yingjiang county and Kaiyuan city, HIV prevalence among IDUs was also higher than 40% [8]. Another study demonstrated HIV prevalence among Kaiyuan's IDUs was as high as 59.9% in 2007 [10]. From 1992 to 2009, 3591 IDUs were tested for HIV and the average infection rate was 3.15% in Baoshan [11].

Besides HIV, the prevalence of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection among IDUs is also alarming. Previous studies conducted in 2007 showed 68.1% IDUs were infected with HCV in Yunnan [12]. Another study estimated in 2009 the rate of HCV positive was 83.33% among Yunnan IDUs [13]. Tian et al found the infection rate among Yunnan IDUs was 69.7% for HCV and 36.45% for HBV [14]. Meanwhile, HCV and HBV infection among IDUs in Dehong was 35.3% and 52.9%, respectively [15]. Due to sharing the similar transmission mode, co-infection with HIV and hepatitis viruses is quite frequent amongst IDUs sharing needles/syringes with each other [16]. It was indicated the rate of sharing injecting equipment was as high as 59.4% among HIV-infected IDUs in Yunnan [9], and 93.3% to 99.3% of them were co-infected with HCV [12], [17]. High prevalence of co-infection with HCV (92%) or HBV (71%) among HIV positive IDUs was also reported in Ruili county, Yunnan province [18].

Previous studies have confirmed that HIV co-infection can accelerate the clinical course of chronic HCV or HBV infection and increase the risks of liver cirrhosis, hepatocellular carcinoma (HCC) and decompensated liver disease [19], [20]. Although the effects of HCV or HBV on HIV are controversial, some studies have shown HIV positive patients co-infected with HCV and/or HBV have more rapid progression of AIDS and related death compared with patients without co-infections [21]. Additionally, co-infection with HCV and HBV is not uncommon among IDUs, and patients with dual HCV and HBV infection have more severe liver disease with increasing risk for progression to HCC [22]. Therefore, it is indispensable to investigate and ascertain the prevalence of the co-infection of HIV and HCV and/or HBV, or HCV and HBV to understand the true burden of disease among IDUs.

HIV infection among IDUs has been well recognized in Yunnan, China. However, limited data are available on the prevalence of HCV, HBV and co-infection with HIV and HCV and/or HBV, or HCV and HBV, especially in respective prefecture. Therefore, a cross-sectional study was conducted to estimate the prevalence of HIV, HCV, HBV and co-infection with 2 or 3 viruses and evaluate risk factors among IDUs in Yunnan province.

Abstract.
Objective.

To estimate the prevalence of HIV, HCV, HBV and co-infection with 2 or 3 viruses and evaluate risk factors among injecting drug users (IDUs) in Yunnan province, China.

Methods.

2080 IDUs were recruited from 5 regions of Yunnan Province, China to detect the infection status of HIV, hepatitis B virus (HBV) and hepatitis C virus (HCV). Statistical analysis was performed to evaluate risk factors related to HIV, HCV and HBV infections.

Results.

The infection rates among all participants were 25.5% for HIV, 77.7% for HCV, 19.2% for HBV, 15% for HIV/HCV, 0.3% for HIV/HBV, 7.8% for HCV/HBV and 7.1% for HIV/HCV/HBV. The prevalence of virus infection varied widely by region in Yunnan of China. Statistical analyses indicated that high prevalence of HIV and HCV among IDUs was positively associated with the duration of drug injection and sharing needles/syringes; besides, HCV infection was associated with the frequency of drug injection.

Conclusions.

HIV, HCV, HBV infections and co-infections were still very prevalent among IDUs in Yunnan province because of drug use behaviors.