Molecular epidemiology of HIV-1 Infection in Taiwan: Further Spread of CRF07_BC and the Emergence of Dual Infection

• Main Authors: Yen-Ju Chen, 陳沿如
• Other Authors: Yi-Ming Chen
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/83771352644651383690

博士 === 國立陽明大學 === 公共衛生研究所 === 100 === Background: Previous surveys on the trends of subtype distribution in Taiwan reported that HIV-1 subtype B had been the major subtype. The epidemiology of HIV-1 infection in 2004 saw a dramatic change with the epidemiological curve became exponential and the major transmission route shifted from unprotected sexual intercourse to drug solution sharing and injection equipment sharing. However, injection drug users (IDUs) not only share drug solutions or injection paraphernalia but also have sexual contacts. We hypothesized that CRF07_BC may have been transmitted from IDUs to other risk groups through unprotected sexual intercourse. In addition, individuals involved in higher risky behaviors may be at a higher risk of becoming dual-infection carriers. We therefore conducted a molecular epidemiological study to examine the distribution trends and risk factors for different HIV-1 subtypes. In addition, we tried to determine the differences in risk factor profiles across the different populations in Taiwan from 2005 to 2008. Materials and methods: In total 1,133 HIV-1-infected adults including 576 IDUs (including 11 MSM/IDU and 3 female Bi/IDU), 464 MSM and 93 heterosexuals were recruited. HIV-1 subtypes were determined using nested multiplex PCR and phylogenetic analysis. Dual infection was confirmed using cloning, sequencing and heteroduplex mobility assay (HMA). Results: The male to female ratio of the study population was approximately 8:1. The mean age was 33.4 ± 7.9 years, and the infected male heterosexuals were significantly older than members of the other risk groups except for male IDUs (ANOVA test, p < 0.001). Most subjects (60.8%) had received education up to senior high school, but male IDUs and women had a lower education level (Pearson’s X2 test, p < 0.001). In addition, 73.0% (747/1023) of the subjects were single. About half of the subjects had traveled overseas, especially in Southeast Asia. About ten percent (79/789) of subjects had had sexual intercourse with sex workers. Subtype B was predominant in all male risk groups except for IDUs who were mainly infected with CRF07_BC. Heterosexual females were mainly infected with CRF01_AE. Forty-nine patients had CRF07_BC/subtype B dual infection and 44 (89.8%) were IDUs. Multivariate logistic regression showed that the odds ratio for dual infection among IDUs who shared syringes > 5 times per month was 4.7 (95% CI = 1.3 - 17.7). Phylogenetic analyses revealed that there were two main groups of CRF07_BC strains with sporadic transmission between different risk groups. Among 10 IDUs infected with CRF01_AE, 7 cases were clustered with an outbreak happened in 2005 and 3 cases were clustered with other strains from heterosexual population. Conclusions: In Taiwan, 7.8% of HIV-1-infected IDUs had dual infection. It may have important impact to their clinical management. Although CRF07_BC was still remained in IDUs, it has spread to MSM and heterosexual populations.