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A total of 1155 partial pol gene sequences of human immunodeficiency virus (HIV)-1 CRF07_BC were sampled between 1997 and 2015, spanning 13 provinces in Mainland China and risk groups [heterosexual, injecting drug users (IDU), and men who have sex with men (MSM)] to investigate the evolution, adaptation, spatiotemporal and risk group dynamics, migration patterns, and protein structure of HIV-1 CRF07_BC. Due to the unequal distribution of sequences across time, location, and risk group in the complete dataset ('full1155'), subsampling methods were used. Maximum-likelihood and Bayesian phylogenetic analysis as well as discrete trait analysis of geographical location and risk group were carried out. To study mutations of a cluster of HIV-1 CRF07_BC (CRF07-1), we performed a comparative analysis of this cluster to the other CRF07_BC sequences ('backbone_295') and mapped the mutations observed in the respective protein structure. Our findings showed that HIV-1 CRF07_BC most likely originated among IDU in Yunnan Province between October 1992 to July 1993 [95 per cent hightest posterior density (HPD): May 1989–August 1995] and that IDU in Yunnan Province and MSM in Guangdong Province likely served as the viral sources during the early and more recent spread in Mainland China. We also revealed that HIV-1 CRF07-1 has been spreading for roughly 20 years and continues to cause local transmission in Mainland China and worldwide. Overall, our study sheds light on the dynamics of HIV-1 CRF07_BC distribution patterns in Mainland China. Our research may also be useful in formulating public health policies aimed at controlling acquired immune deficiency syndrome in Mainland China and globally. [ABSTRACT FROM AUTHOR]

Background We aimed to forecast the number of unidentified and newly acquired HIV-infected individuals each year and to estimate the effectiveness of government prevention and control programs in China. Methods Dynamic and stochastic models were established based on officially published data regarding the four main modes of transmission: male homosexual sexual behavior, heterosexual sexual behavior, injection drug use (IDU) and plasma donation. Finally, we performed sensitivity analyses on model parameters. Results Nationally, by December 2016, approximately 280 790 individuals were estimated to have an unidentified HIV infection, with transmission via male homosexual sexual behavior (n  = 100 710), heterosexual sexual behavior (n  = 174 310), IDU (n  = 5 620) and plasma donation (n  = 150). Moreover, 196 970 newly acquired HIV-infected individuals were expected in 2016, via male homosexual sexual behavior (n  = 78 610), heterosexual sexual behavior (n  = 116,540), IDU (n  = 1820), and plasma donation (n  < 2). Conclusions Our results show that HIV transmission via IDU and plasma donation has been effectively controlled; transmission via heterosexual sexual contact is being somewhat controlled; however, transmission via male homosexual sexual contact is not controlled. Hence, China should strengthen efforts aimed at control of unsafe sexual behaviors. [ABSTRACT FROM AUTHOR]

Contact tracing, coupled with molecular epidemiologic investigation, is especially useful for identifying an infection with few cases in the population, such as human immunodeficiency virus (HIV) infection in China. No such research is available on Chinese men who have sex with men (MSM). From 2008 to 2010 in Taizhou Prefecture in China, every newly diagnosed HIV-infected MSM was invited to participate as an “index case” in a contact tracing survey by providing contact information for up to 8 sexual contacts, who themselves were approached to receive voluntary HIV counseling and testing. Those who tested HIV-positive were then subjected to another contact tracing survey. This process was repeated until no more sexual contacts were reported or tested positive. A total of 100 HIV-infected MSM served as “index cases,” including the initial 49 cases identified through routine surveillance programs and 51 cases from the present survey. Traced MSM exhibited little willingness to receive voluntary counseling and testing. CRF01_AE (HIV type 1) was the dominant subtype. Seven of 49 independent sexual networks were deemed HIV transmission clusters. Fear of stigma or discrimination may deter Chinese MSM from receiving voluntary counseling and testing. Nonetheless, the integration of behavioral network analysis and HIV phylogenetic analysis provides enhanced evidence for developing tailored prevention strategies for HIV-infected MSM. [ABSTRACT FROM PUBLISHER]

Background To monitor the prevalence of HIV and syphilis as well as behaviours, a sentinel site for men who have sex with men was established in Harbin in 2002. With additional funding, the sentinel surveillance evolved into annual cross-sectional surveys since 2006.Methods Behavioural and serological data collected in five consecutive cross-sectional surveys were analysed. SPSS 13.0 was applied to compare prevalence of HIV and syphilis as well as behavioural variables over time by demographic variables, bivariate and multivariate analysis.Results The prevalence of HIV and syphilis increased from 1.0% in 2006 to 7.5% in 2010 and from 9.2% in 2006 to 22.4% in 2009, respectively, whereas the rate of unprotected anal intercourse decreased from 61.3% in 2006 to 47.1% in 2010. Syphilis positivity and HIV infection are independently associated with each other across years. The rate of unprotected anal sex remains high although it has decreased over the years.Conclusion Findings support an increasing prevalence of HIV and syphilis among men who have sex with men in Harbin. Targeted behavioural intervention and syphilis treatment are urgently needed to prevent the epidemic from growing. [ABSTRACT FROM AUTHOR]