***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background : In the And ean Region , HIV and sexually transmitted infections ( STI ) are most prevalent among men who have sex with men ( MSM ) , but incidence estimates and associated factors have never been prospect ively assessed . Methods : A cohort of 1056 high-risk HIV-negative MSM in Lima , Peru , were recruited during 1998 - 2000 ( the ALASKA Cohort ) , and a nested case-control analysis was conducted between seroconverters and nonseroconverters , matched 1:3 by age and duration of follow-up for comparison of risk behaviors , acute retroviral symptoms , circumcision , and STI . Results : During average follow-up of 335 days , 34 men seroconverted , providing a HIV incidence estimate of 3.5 per 100 person-years [ 95 % confidence interval ( CI ) : 2.3 to 4.7 ] . High syphilis ( 8.4 per 100 person-years , 95 % CI : 6.7 to 10.1 ) and herpes simplex virus type 2 ( HSV-2 ) infection ( 10.4 per 100 person-years , 95 % CI : 8.6 to 11.9 ) incidence estimates were obtained . HIV seroconverters were more likely than men who remained seronegative to report fever ≥3 days ( 46 % vs. 7 % ) , to seek medical care ( 62 % vs. 27 % ) , and to have ≥1 casual partner ( 86.2 % vs. 74.1 % ) since their last visit . HIV seroconverters also were more likely to have acquired syphilis or HSV-2 infection ( 31 % vs. 8 % among initially HSV-2-seronegative men ) although they were less likely to be circumcised ( 4.2 % vs. 20.6 % , a nonsignificant difference ) . In multivariate analysis , incident syphilis or HSV-2 infection ( odds ratio [ OR ] : 5.9 , 95 % CI : 1.5 to 22.7 ) and sex with any casual partner ( OR : 4.8 , 95 % CI : 0.9 to 26.2 ) were associated with HIV seroconversion . Conclusions : STI that may cause anogenital ulcers are important risk factors for HIV acquisition among high-risk MSM in Lima , a population with a very high HIV incidence estimate . Synergistic interventions focusing in preventing both HIV and HSV-2 , like male circumcision , are warranted to be assessed , especially in MSM population s with low levels of circumcision and high incidence estimates of ulcerative STI Background Although HIV treatment as prevention ( TasP ) via early antiretroviral therapy ( ART ) has proven to reduce transmissions among HIV-serodiscordant couples , its full implementation in developing countries remains a challenge . In this study , we determine whether China 's current HIV treatment program prevents new HIV infections among discordant couples in rural China . Methods A prospect i ve , longitudinal cohort study was conducted from June 2009 to March 2011 , in rural Yunnan . A total of 1,618 HIV-discordant couples were eligible , 1,101 were enrolled , and 813 were followed for an average of 1.4 person-years ( PY ) .  Routine ART was prescribed to HIV-positive spouses according to eligibility ( CD4<350 cells/µl ) . Seroconversion was used to determine HIV incidence . Results A total of 17 seroconversions were documented within 1,127 PY of follow-up , for an overall incidence of 1.5 per 100 PY . Epidemiological and genetic evidence confirmed that all 17 seroconverters were infected via marital secondary sexual transmission . Having an ART-experienced HIV-positive partner was associated with a lower rate of seroconvertion compared with having an ART-naïve HIV-positive partner ( 0.8 per 100 PY vs. 2.4 per 100 PY , HR = 0.34 , 95%CI = 0.12–0.97 , p = 0.0436 ) . While we found that ART successfully suppressed plasma viral load to < 400 copies/ml in the majority of cases ( 85.0 % vs. 19.5 % , p<0.0001 at baseline ) , we did document five seroconversions among ART-experienced subgroup . Conclusions ART is associated with a 66 % reduction in HIV incidence among discordant couples in our sample , demonstrating the effectiveness of China 's HIV treatment program at preventing new infections , and providing support for earlier ART initiation and TasP implementation in this region Introduction : We explored factors associated with differential HIV incidence among women participating in a HIV prevention trial in Harare , Durban , and Johannesburg . The trial had shown no effect of the intervention ( diaphragm and lubricant gel ) on HIV incidence . Methods : A prospect i ve cohort analysis was conducted of trial participants followed for 12 - 24 months . Sociodemographic , biological , and behavioral data were collected at baseline and at quarterly visits . Factors associated with HIV incidence were estimated using multivariable Cox regression models , stratified by study location . Attributable risk was calculated from the adjusted hazard ratios ( AHR ) . Results : There were 309 incident HIV infections among the 4948 women in the analysis .  HIV incidence was highest in Durban [ 6.75/100 person-years ; 95 % confidence interval ( CI ) : 5.74 to 7.93 ] , lower in Johannesburg ( 3.33/100 person-years ; 95 % CI : 2.51 to 4.44 ) , and lowest in Harare ( 2.72/100 person-years ; 95 % CI : 2.26 to 3.26 ) . Sexually transmitted infections were important risk factors in Harare [ prevalent herpes simplex virus type 2 ( HSV2 ) AHR = 2.56 , 95 % CI : 1.61 to 4.06 ; incident HSV2 AHR = 12.60 , 95 % CI : 2.13 to 21.87 ; Neisseria gonorrhoeae AHR = 6.82 , 95 % CI : 2.13 to 21.87 ] and in Durban ( prevalent HSV2 AHR = 1.64 , 95 % CI : 1.07 to 2.51 ; N. gonorrhoeae AHR = 4.40 , 95 % CI : 2.07 to 9.39 ) . In Durban , having multiple partners ( adjusted odds ratio ( AOR ) = 1.78 95 % CI : 1.11 to 2.85 ) and sex although a partner was under the influence of alcohol/drugs ( AOR = 1.51 95 % CI : 1.05 to 2.16 ) significantly increased risk , whereas in Johannesburg , sexual debut < 16 years ( AOR = 2.60 95 % CI : 1.30 to 5.17 ) was a strong predictor of HIV acquisition . Discussion : Important differences were seen in drivers of HIV incidence at the 3 study locations . Results from this analysis imply that targeted HIV programing could have a large impact on incident HIV infection in women , and that the most effective approach will likely vary based on knowledge of the local situation/epidemiology Objective : We assessed the protective effect of medical male circumcision ( MMC ) against HIV , herpes simplex virus type 2 ( HSV-2 ) , and genital ulcer disease ( GUD ) incidence . Design : Two thous and , seven hundred and eighty-seven men aged 18–24 years living in Kisumu , Kenya were r and omly assigned to circumcision  ( n=1391 ) or delayed circumcision  ( n = 1393 ) and assessed by  HIV and HSV-2 testing and medical examinations during follow-ups at 1 , 3 , 6 , 12 , 18 , and 24 months . Methods : Cox regression estimated the risk ratio of each outcome ( incident HIV , GUD , HSV-2 ) for circumcision status and multivariable models estimated HIV risk associated with HSV-2 , GUD , and circumcision status as time-varying covariates . Results : HIV incidence was 1.42 per 100 person-years . Circumcision was 62 % protective against HIV [ risk ratio = 0.38 ; 95 % confidence interval ( CI ) 0.22–0.67 ] and did not change when controlling for HSV-2 and GUD ( risk ratio = 0.39 ; 95 % CI 0.23–0.69 ) . GUD incidence was halved among circumcised men ( risk ratio = 0.52 ; 95 % CI 0.37–0.73 ) . HSV-2 incidence did not differ by circumcision status ( risk ratio = 0.94 ; 95 % CI 0.70–1.25 ) . In the multivariable model , HIV seroconversions were tripled ( risk ratio = 3.44 ; 95 % CI 1.52–7.80 ) among men with incident HSV-2 and seven times greater ( risk ratio = 6.98 ; 95 % CI 3.50–13.9 ) for men with GUD . Conclusion : Contrary to findings from the South African and Ug and an trials , the protective effect of  MMC against HIV was independent of GUD and HSV-2 , and MMC had no effect on HSV-2 incidence . Determining the causes of GUD is necessary to reduce associated HIV risk and to underst and how circumcision confers protection against GUD and HIV BACKGROUND Male circumcision could provide substantial protection against acquisition of HIV-1 infection . Our aim was to determine whether male circumcision had a protective effect against HIV infection , and to assess safety and changes in sexual behaviour related to this intervention . METHODS We did a r and omised controlled trial of 2784 men aged 18 - 24 years in Kisumu , Kenya . Men were r and omly assigned to an intervention group ( circumcision ; n=1391 ) or a control group ( delayed circumcision , 1393 ) , and assessed by  HIV testing , medical examinations , and behavioural interviews during follow-ups at 1 , 3 , 6 , 12 , 18 , and 24 months . HIV seroincidence was estimated in an intention-to-treat analysis . This trial is registered with Clinical Trials.gov , with the number NCT00059371 . FINDINGS The trial was stopped early on December 12 , 2006 , after a third interim analysis review ed by the data and safety monitoring board . The median length of follow-up was 24 months . Follow-up for HIV status was incomplete for 240 ( 8.6 % ) participants . 22 men in the intervention group and 47 in the control group had tested positive for HIV when the study was stopped . The 2-year HIV incidence was 2.1 % ( 95 % CI 1.2 - 3.0 ) in the circumcision group and 4.2 % ( 3.0 - 5.4 ) in the control group ( p=0.0065 ) ; the relative risk of HIV infection in circumcised men was 0.47 ( 0.28 - 0.78 ) , which corresponds to a reduction in the risk of acquiring an HIV infection of 53 % ( 22 - 72 ) . Adjusting for non-adherence to treatment and excluding four men found to be seropositive at enrollment , the protective effect of circumcision was 60 % ( 32 - 77 ) . Adverse events related to the intervention ( 21 events in 1.5 % of those circumcised ) resolved quickly . No behavioural risk compensation after circumcision was observed . INTERPRETATION Male circumcision significantly reduces the risk of HIV acquisition in young men in Africa . Where appropriate , voluntary , safe , and affordable circumcision services should be integrated with other HIV preventive interventions and provided as expeditiously as possible Vaginal Gel Versus HIV HIV prevention technologies for women are urgently needed , especially in sub-Saharan Africa where young women bear the greatest burden of the HIV epidemic . Abdool Karim et al. ( p. 1168 ; published online 19 July ) present the results of the CAPRISA 004 r and omized control trial . The nearly 3-year-long trial , conducted in urban and rural South African women , tested the efficacy of a vaginal gel containing the antiretroviral drug tenofovir in preventing HIV infection . The dosing strategy required application of the gel both before and after coitus , and with this regime HIV infection was reduced by approximately 39 % overall , by 54 % in women with high adherence to the protocol , and with no increase in overall adverse event rates . Tenofovir in a vaginal gel formulation shows significant protection against HIV infection in a r and omized control trial . The Centre for the AIDS Program of Research in South Africa ( CAPRISA ) 004 trial assessed the effectiveness and safety of a 1 % vaginal gel formulation of tenofovir , a nucleotide reverse transcriptase inhibitor , for the prevention of HIV acquisition in women . A double-blind , r and omized controlled trial was conducted comparing  tenofovir gel ( n = 445 women ) with  placebo gel ( n 
    Output:
    
Interpretation We found evidence that HSV-2 infection increases the risk of HIV acquisition .
Interventions targeting HSV-2 , such as new HSV vaccines , have the potential for additional benefit against HIV , which could be particularly powerful in regions with a high incidence of co-infection .