專題討論3:感控

S3-4
台灣愛滋病病毒分子流行病學及世代追蹤研究
Molecular Epidemiology and Cohort Study of HIV-1 Infection in Taiwan
陳宜民 Yi-Ming Arthur Chen1, 2
1Center for Infectious Disease and Cancer Research (CICAR) Kaohsiung Medical University, Kaohsiung, Taiwan 2Department of Microbiology and Institute of Medical Research, Kaohsiung Medical University, Kaohsiung, Taiwan
高雄醫學大學醫學院醫學系微生物學科教授兼學術副校長

Background: In 2004, HIV-1 infection among Taiwanese injection drug users (IDUs) started to surge. In 2007, a resurgence of HIV-1 epidemic among men who have sex with men (MSM) occurred. The objectives of this study were a.) To evaluate the extent of CRF07_BC infection in different susceptible populations besides IDUs in Taiwan; b.) To conduct a clinical epidemiological study using a cohort of patients infected with subtype B and CRF07_BC; and c.) To conduct a survey on MSM population in Taipei to identify risk factors associated with HIV-1 infection.

Methods: In total, 1133 HIV-1–infected adults including 576 IDUs, 464 MSM, and 93 heterosexuals were recruited from 2005 to 2008. HIV-1 subtypes were determined using nested multiplex polymerase chain reaction and phylogenetic analysis. Dual infection was confirmed using cloning, sequencing, and heteroduplex mobility assay. Besides, a nested case-control study consisted of 21 patients infected with CRF07_BC and 59 patients with subtype B was conducted using a cohort of 667 HIV-1/AIDS patients. Generalized estimated equation was used for statistical analysis. For the third study, voluntary counseling program and anonymous testing were provided to patrons at 8 gay bars and 3 gay saunas in Taipei and New Taipei Cities. Questionnaires and blood specimens were collected. Detuned test was used to estimate incidence. Risk factors were identified using multivariate analysis.

Results: Among HIV-1/AIDS subjects, 96.1% MSM and 62.5% heterosexual males were infected with subtype B, whereas 66.7% female heterosexuals were infected with CRF01_AE. Most IDUs (84.5%) were infected with CRF07_BC. Four heterosexual males, 2 females and 2 MSM who were not IDUs had CRF07_BC. 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 more than 5 times per month was 4.7 (95% confidence interval = 1.3 to 17.7). Phylogenetic analyses revealed that there were 2 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.
Concerning the cohort study, subtype B was predominant in MSM and heterosexuals with 93.9% and 69.6%, respectively. In contrast, 74.3 % of IDUs were infected with CRF07_BC. A nested case-control study showed that the mean viral loads of treatment-naive patients infected with subtype B or CRF07_BC were 54,362 and 15,749 copies/ml, respectively (p = 0.002).

Concerning the HIV-1 survey on the MSM in 2012, 4.5% (53/1191) of participants had HIV-1 infection. The incidence rate is 5.84 per 100 person years. Multivariate logistic regression showed that risk factors for HIV-1 infection were: exclusively receptive role (vs. exclusively insertive, OR = 2.89; p = 0.049); times of sexual contact per week (1-3 vs. < 1 per week, O R= 2.44; p = 0.042); recreational drugs usage (OR = 4.38; p <0.001); use oil- or petroleum-based lubricants during sexual intercourse (vs. saliva or water-base lubricant, OR = 4.6; p = 0.001); and history of having sexually transmitted diseases (OR = 2.9; p = 0.019).

Conclusion: 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 with smaller scale than we predicted. Patients infected with CRF07_BC had significantly lower viral loads than patients infected with subtype B. It may be due to the low replication capacity and poor protease-mediated processing of CRF07_BC strains. Using oils or petroleum-based lubricants during sexual intercourse is a neglected risk factor for MSM in Taiwan. Continuous education and intervention campaign on this issue are urgently needed.

Keywords: molecular epidemiology, CRF07_BC, men who have sex with men, injection drug users, prevalence, incidence rate, risk factor, lubricants.