Risky sexual networks and concentrated HIV epidemics among men who have sex with men in Wenzhou, China: a respondent-driven sampling study.

BACKGROUND: The high and continually increasing prevalence of human immunodeficiency virus (HIV) and other sexually transmitted diseases among men who have sex with men (MSM) in China underscores the critical importance of examining the exact sexual networks that result in HIV transmission, as well as HIV infection, using powerful sampling methods, such as respondent-driven sampling (RDS), to improve the sexual health of this population. METHODS: Using RDS, a cross-sectional study was conducted among MSM in Wenzhou, Zhejiang province, China from December 2013 to June 2014. The type of sex, numbers of anal sex partners, male oral sex partners and vaginal sex partners, condom use during each type of sex over the previous 6 months, prevention behaviors, risk perception, and the burdens of HIV and syphilis were investigated and analyzed. RESULTS: Of 424 MSM, a great number of them did anal sex, male oral sex, and vaginal sex during the previous 6 months, and weighted estimates for the prevalence that MSM did not conduct these sexual behaviors were 11.2 % (95 % confidence interval [CI] =6.7-16.50 %), 20.3 % (95 % CI = 15.2-27.1 %), and 58.9 % (95 % CI = 52.1-65.8 %), respectively. Multiple sexual partners, engaging in regular, casual and commercial sex, and lack of condom use during all types of sex were common among MSM. The estimated HIV and syphilis prevalences were 22.8 % (95 % CI = 16.9-28.5 %) and 9.7 % (95 % CI = 6.4-13.6 %), respectively. Of the participants, 53.5 % (95 % CI = 45.3-60.2 %) received HIV-related interventions during the previous year, 48.1 % (95 % CI = 39.7-55.1 %) had never been tested for HIV, and only 14.1 % (95 % CI =10.1-19.2 %) perceived a risk of contracting HIV. Multiple logistic regression analysis revealed that age over 44 years (adjusted odds ratio [AOR] = 3.60, 95 % CI = 1.34-9.64), a monthly income of 3001-4000 yuan (approximately 470-630 US$) (AOR = 1.96, 95 % CI = 1.67-3.60), multiple anal sex partners (AOR = 1.93, 95 % CI = 1.15-3.24), awareness of the possibility of contracting HIV (AOR = 3.18, 95 % CI = 1.56-6.48), and current syphilis infection (AOR = 3.01, 95 % CI = 1.44-6.29) were predictors of HIV infection. CONCLUSIONS: HIV transmission has become highly prevalent and will likely become more prevalent among MSM and their female partners if these risky sexual networks persist. Our findings call for urgent and effective interventions to prevent the rapid transmission of HIV among MSM in Wenzhou.

High prevalence of HIV among men who have sex with men in Zhejiang, China: a respondent-driven sampling survey.

OBJECTIVES: To examine the prevalence of HIV and risk behaviours among men who have sex with men (MSM) and to explore the feasibility of using respondent-driven sampling in this population in order to conduct customised interventions among MSM in the future. DESIGN: Cross-sectional study. SETTING: Zhejiang, China. PARTICIPANTS: 1316 MSM. PRIMARY AND SECONDARY OUTCOME MEASURES: HIV prevalence rates and factors associated with HIV infection; sociodemographic and behavioural information of participants, syphilis prevalence rates. RESULTS: The adjusted prevalence of HIV and syphilis were 13.8% and 11.4%, respectively. Multivariate analysis showed that higher educational level, support treatment of HIV, negative syphilis are protective factors of HIV infection. MSM who had heterosexual behaviour before and whose primary sexual partner was HIV-positive were less likely to be infected with HIV compared with their counterparts, while frequency of sexual behaviour with primary sexual partner was positively associated with HIV infection. CONCLUSIONS: This survey confirmed a high HIV prevalence among MSM in Zhejiang province. MSM are extremely vulnerable to HIV infection and comprehensive interventions are urgently needed to slow the spread of HIV among MSM.

[The molecular epidemiologic investigation of hantavirus carried by rodent hosts in Wenzhou, Zhejiang province].

OBJECTIVE: To study the epidemiological features of hantavirus in rodents in Wenzhou, Zhejiang province. METHODS: Rodents were captured in Wenzhou, where hemorrhagic fever with renal syndrome (HFRS) had been endemic. Hantavirus antigens in the rat lungs were detected by immunofluorescence assay (IFA). Partial S segment (nt 620-999) and partial M segment (nt 2001-2301) sequences were amplified by RT-PCR, and then sequenced. Neighbor-joining method was used to construct for phylogenetic analysis. RESULTS: A total of 96 rodents were trapped in the epidemic areas, and 6 hantavirus antigens were identified from these lung samples (6.3%). Partial S and partial M segment sequences were successfully recovered from 5 samples and determined. Phylogenetic analysis of these sequences indicated that all viruses belonged to Seoul virus (SEOV), regardless of the sources (Rattus norvegicus, Rattus tanezumi and Rattus rattoide) that they were derived. However, the clustering pattern in the partial S-tree was different from that in the partial M-tree, suggesting that the re-assortment between SEOVs had occurred. CONCLUSION: All Rattus rats carried SEOV in Wenzhou and the genetic reassortment with SEOV had occurred naturally.