Male circumcision and prevention of HIV and sexually transmitted infections

Does Voluntary Medical Male Circumcision Reduce HIV Risk in Men Who Have Sex with Men?

PURPOSE OF REVIEW

To review the evidence on the effect of voluntary medical male circumcision (VMMC) on reducing HIV risk among men who have sex with men (MSM) and assess the limitations of available evidence.

RECENT FINDINGS

Individual studies have shown conflicting results, but recent meta-analyses have consistently suggested that VMMC was associated with 7 to 23% reductions in HIV prevalence or incidence in MSM, particularly among a subgroup of men who predominantly practice insertive role in anal sex. Mathematical models have also suggested a moderate population-level impact of VMMC intervention. All original studies have been observational and are subject to confounding and bias. Randomized clinical trials (RCTs) are needed to provide strong evidence of assessing the efficacy of VMMC on HIV risk among MSM. VMMC is a promising HIV risk reduction tool for MSM. RCTs are needed to evaluate the efficacy of VMMC intervention.

Male circumcision for HIV prevention: Awareness, risk compensation, and risk perceptions among South African women

Medical male circumcision (MMC) is a proven method of HIV risk reduction for men in southern Africa. MMC promotion campaigns and scale-up programmes are widely implemented throughout the Republic of South Africa. However, the impact of promoting MMC on women's awareness, beliefs, and behaviours has been understudied. We conducted a self-administered anonymous survey of 279 women receiving health services in an impoverished township located in Cape Town, South Africa. Results showed that two in three women were unaware that male circumcision partially protects men from contracting HIV. Women who were aware of MMC for HIV prevention also endorsed beliefs that male circumcision reduces the need for men to worry about HIV and reduces the need for men to use condoms. Male circumcision awareness was also related to reduced perceptions of HIV risk among women. Multivariable models showed that women's MMC awareness, circumcision risk compensation beliefs, and risk perceptions were associated with decreased condom use and higher HIV risk index scores defined as number of condomless vaginal intercourse X number of sex partners. These results suggest a need for MMC education efforts tailored for women living in communities with high-HIV prevalence where men are targeted for MMC.

Lower HIV Risk Among Circumcised Men Who Have Sex With Men in China: Interaction With Anal Sex Role in a Cross-Sectional Study

BACKGROUND

Voluntary medical male circumcision reduces the risk of HIV heterosexual transmission in men, but its effect on male-to-male sexual transmission is uncertain.

METHODS

Circumcision status of men who have sex with men (MSM) in China was evaluated by genital examination and self-report; anal sexual role was assessed by questionnaire interview. Serostatus for HIV and syphilis was confirmed.

RESULTS

Among 1155 participants (242 were seropositive and 913 with unknown HIV status at enrollment), the circumcision rate by self-report (10.4%) was higher than confirmed by genital examination (8.2%). Male circumcision (by examination) was associated with 47% lower odds of being HIV seropositive [adjusted odds ratio (aOR): 0.53; 95% confidence interval (CI): 0.27 to 1.02] after adjusting for demographic covariates, number of lifetime male sexual partners, and anal sex role. Among MSM who predominantly practiced insertive anal sex, circumcised men had 62% lower odds of HIV infection than those who were uncircumcised (aOR: 0.38; 95% CI: 0.09 to 1.64). Among those whose anal sex position was predominantly receptive or versatile, circumcised men have 46% lower odds of HIV infection than did men who were not circumcised (aOR: 0.54; 95% CI: 0.25 to 1.14). Compared to uncircumcised men reporting versatile or predominantly receptive anal sex positioning, those who were circumcised and reported practicing insertive sex had an 85% lower risk (aOR: 0.15; 95% CI: 0.04 to 0.65). Circumcision was not associated clearly with lower syphilis risk (aOR: 0.91; 95% CI: 0.51 to 1.61).

CONCLUSIONS

Circumcised MSM were less likely to have acquired HIV, most pronounced among men predominantly practicing insertive anal intercourse. A clinical trial is needed.

Male circumcision and HIV infection risk

BACKGROUND

Male circumcision is being promoted to reduce human immunodeficiency virus type 1 (HIV) infection rates. This review evaluates the scientific evidence suggesting that male circumcision reduces HIV infection risk in high-risk heterosexual populations.

METHODS

We followed the updated International Consultation on Urological Diseases evidence-based medicine recommendations to critically review the scientific evidence on male circumcision and HIV infection risk.

RESULTS

Level 1 evidence supports the concept that male circumcision substantially reduces the risk of HIV infection. Three major lines of evidence support this conclusion: biological data suggesting that this concept is plausible, data from observational studies supported by high-quality meta-analyses, and three randomized clinical trials supported by high-quality meta-analyses.

CONCLUSIONS

The evidence from these biological studies, observational studies, randomized controlled clinical trials, meta-analyses, and cost-effectiveness studies is conclusive. The challenges to implementation of male circumcision as a public health measure in high-risk populations must now be faced.

Abundant expression of HIV target cells and C-type lectin receptors in the foreskin tissue of young Kenyan men

A biological explanation for the reduction in HIV-1 (HIV) acquisition after male circumcision may be that removal of the foreskin reduces the number of target cells for HIV. The expression of potential HIV target cells and C-type lectin receptors in foreskin tissue of men at risk of HIV infection were thus analyzed. Thirty-three foreskin tissue samples, stratified by Herpes simplex virus type 2 status, were obtained from a randomized, controlled trial conducted in Kenya. The samples were analyzed by confocal in situ imaging microscopy and mRNA quantification by quantitative RT-qPCR. The presence and location of T cells (CD3(+)CD4(+)), Langerhans cells (CD1a(+)Langerin/CD207(+)), macrophages (CD68(+) or CD14(+)), and submucosal dendritic cells (CD123(+)BDCA-2(+) or CD11c(+)DC-SIGN(+)) were defined. C-type lectin receptor expressing cells were detected in both the epithelium and submucosa, and distinct lymphoid aggregates densely populated with CD3(+)CD4(+) T cells were identified in the submucosa. Although the presence of lymphoid aggregates and mRNA expression of selected markers varied between study subjects, Herpes simplex virus type 2 serostatus was not the major determinant for the detected differences. The detection of abundant and superficially present potential HIV target cells and submucosal lymphoid aggregates in foreskin mucosa from a highly relevant HIV risk group demonstrate a possible anatomical explanation that may contribute to the protective effect of male circumcision on HIV transmission.

Male circumcision to reduce the risk of HIV and sexually transmitted infections among men who have sex with men

PURPOSE OF REVIEW

The success of male circumcision in reducing HIV acquisition among African heterosexuals has led to renewed interest in this biological intervention for HIV/sexually transmissible infection (STI) prevention in men who have sex with men (MSM). This review summarizes the available data on the association of circumcision and HIV/STI among MSM populations.

RECENT FINDINGS

Results of observational studies indicate that circumcision has limited impact on HIV/STI acquisition among MSM populations overall. Longitudinal data suggest that circumcision may reduce the risk of incident syphilis, but there is little evidence of a protective effect for other STIs. The subgroup of MSM who predominantly practise the insertive role in anal intercourse may be at lower risk of HIV, although the relative inefficiency of HIV acquisition for insertive compared with receptive partners has resulted in imprecise estimates of effect.

SUMMARY

The evidence that circumcision reduces HIV and other STIs among MSM is weak and inconsistent. However, recent studies have found that circumcised MSM who predominantly take the insertive role in anal intercourse may be at a lower risk of HIV infection. Although MSM may be willing to undergo adult circumcision, should it be proven to reduce HIV acquisition risk, there is substantial potential that behavioural disinhibition could offset any benefits achieved by a circumcision intervention.

In vitro and ex vivo testing of tenofovir shows it is effective as an HIV-1 microbicide

BACKGROUND

Tenofovir gel has entered into clinical trials for use as a topical microbicide to prevent HIV-1 infection but has no published data regarding pre-clinical testing using in vitro and ex vivo models. To validate our findings with on-going clinical trial results, we evaluated topical tenofovir gel for safety and efficacy. We also modeled systemic application of tenofovir for efficacy.

METHODS AND FINDINGS

Formulation assessment of tenofovir gel included osmolality, viscosity, in vitro release, and permeability testing. Safety was evaluated by measuring the effect on the viability of vaginal flora, PBMCs, epithelial cells, and ectocervical and colorectal explant tissues. For efficacy testing, PBMCs were cultured with tenofovir or vehicle control gels and HIV-1 representing subtypes A, B, and C. Additionally, polarized ectocervical and colorectal explant cultures were treated apically with either gel. Tenofovir was added basolaterally to simulate systemic application. All tissues were challenged with HIV-1 applied apically. Infection was assessed by measuring p24 by ELISA on collected supernatants and immunohistochemistry for ectocervical explants. Formulation testing showed the tenofovir and vehicle control gels were >10 times isosmolar. Permeability through ectocervical tissue was variable but in all cases the receptor compartment drug concentration reached levels that inhibit HIV-1 infection in vitro. The gels were non-toxic toward vaginal flora, PBMCs, or epithelial cells. A transient reduction in epithelial monolayer integrity and epithelial fracture for ectocervical and colorectal explants was noted and likely due to the hyperosmolar nature of the formulation. Tenofovir gel prevented HIV-1 infection of PBMCs regardless of HIV-1 subtype. Topical and systemic tenofovir were effective at preventing HIV-1 infection of explant cultures.

CONCLUSIONS

These studies provide a mechanism for pre-clinical prediction of safety and efficacy of formulated microbicides. Tenofovir was effective against HIV-1 infection in our algorithm. These data support the use of tenofovir for pre-exposure prophylaxis.

HIV-prevention science at a crossroads: advances in reducing sexual risk

PURPOSE OF REVIEW

We review the current state of evidence-based prevention strategies for reducing sexual transmission of HIV. The combined programmatic and scientific efforts through 2008 to reduce sexual transmission of HIV have failed to reduce substantially the global pandemic.

RECENT FINDINGS

Prevention interventions to reduce HIV infection target behavioral, biomedical, and structural risk factors. Some of these prevention strategies have been evaluated in randomized clinical trials (RCTs) with HIV seroincidence endpoints. When RCTs are not feasible, a variety of observational and quasiexperimental research approaches can provide insight as to program effectiveness of specific strategies. Only five RCTs have demonstrated a notable decrease in sexually acquired HIV incidence. These include the Mwanza study of syndromic management of sexually transmitted diseases and three male circumcision trials in East Africa; a microbicide trial reported in 2009 shows substantial promise for the efficacy of PRO 2000 (0.5% gel).

SUMMARY

The combined programmatic and scientific efforts to reduce sexual transmission of HIV have made incremental progress. New prevention tools are needed to stem the continued spread of HIV, though microbicides and vaccines will take many more years to develop, test, and deploy. Combination strategies of existing modalities should be tested to evaluate the potential for more proximate prevention benefits.

High dead-space syringes and the risk of HIV and HCV infection among injecting drug users

This study examines the association between using and sharing high dead-space syringes (HDSSs)--which retain over 1000 times more blood after rinsing than low dead-space syringes (LDSSs)--and prevalent HIV and hepatitis C virus (HCV) infections among injecting drug users (IDUs). A sample of 851 out-of-treatment IDUs was recruited in Raleigh-Durham, North Carolina, between 2003 and 2005. Participants were tested for HIV and HCV antibodies. Demographic, drug use, and injection practice data were collected via interviews. Data were analyzed using multiple logistic regression analysis. Participants had a mean age of 40 years and 74% are male, 63% are African American, 29% are non-Hispanic white, and 8% are of other race/ethnicity. Overall, 42% of participants had ever used an HDSS and 12% had shared one. HIV prevalence was 5% among IDUs who had never used an HDSS compared with 16% among IDUs who had shared one. The HIV model used a propensity score approach to adjust for differences between IDUs who had used an HDSS and those who had never used one. The HCV models included all potential confounders as covariates. A history of sharing HDSSs was associated with prevalent HIV (odds ratio=2.50; 95% confidence interval=1.01, 6.15). Use and sharing of HDSSs were also associated with increased odds of HCV infection. Prospective studies are needed to determine if sharing HDSSs is associated with increased HIV and HCV incidence among IDUs.