A quantitative risk assessment of multiple factors influencing HIV/AIDS transmission through unprotected sex among HIV-seropositive men

The objective of this study is to conduct a quantitative risk assessment of multiple factors influencing HIV/AIDS transmission through unprotected sexual practices among HIV-seropositive men. A knowledgebase was developed by reviewing different published sources. The data were collected from different sources including Centers for Disease Control and Prevention, selected journals, and reports. The risk pathway scenario tree was developed based on a comprehensive review of published literature. The variables are organized into nine major parameter categories. Monte Carlo simulations for the quantitative risk assessment of HIV/AIDS transmission was executed with the software @Risk 4.0 (Palisade Corporation). Results show that the value for the likelihood of unprotected sex due to having less knowledge about HIV/AIDS and negative attitude toward condom use and safer sex ranged from 1.24 × 10(-5) to 8.47 × 10(-4) with the mean and standard deviation of 1.83 × 10(-4) and 8.63 × 10(-5), respectively. The likelihood of unprotected sex due to having greater anger-hostility, anxiety, less satisfied with aspects of life, and greater depressive symptoms ranged from 2.76 × 10(-9) to 5.34 × 10(-7) with the mean and standard deviation of 5.23 × 10(-8) and 3.58 × 10(-8), respectively. The findings suggest that HIV/AIDS research and intervention programs must be focused on behavior, and the broader setting within which individual risky behaviors occur.     

结果告知对减少新发现HIV感染者不安全性行为的影响

目的分析浦东新区新发现艾滋病病毒（HIV）感染者在结果告知后,不安全性行为的变化情况,为开展HIV感染者/艾滋病（AIDS）病人干预提供依据。方法选择浦东新区2011年1月至2012年6月,新发现的HIV感染者,在结果告知后进行问卷调查。结果首次调查110人,告知后1个月随访109人,6个月随访107人。告知后1个月随访时,不安全性行为的发生比例较告知前减少96.2%;6个月随访时,不安全性行为的发生比例较告知前减少93.8%;不安全性行为次数的中位数由告知前的3次减少到告知后的0次,差异具有统计学意义（P〈0.01）。结论新发现的HIV感染者在结果告知后,不安全性行为明显下降。开展有效的HIV咨询服务,改变感染者的危险性行为,对防止艾滋病的二代传播具有十分重要的意义。     

Influencing HIV transmission risk

Research has shown that there are three primary factors that influence HIV risk behavior: biological, psychological, and social-environmental factors. Biological factors include molecular, genetic, and immunological variations that influence an individual's susceptibility to the virus. Biological factors are also influenced by the co-existence of other sexually transmitted diseases. Psychological factors include intrapersonal characteristics which promote risk-taking behaviors, such as an individual's response to stress or tendency towards substance abuse. Social-environmental factors include the context which surrounds interpersonal behaviors that may lead to HIV risk. Social-environmental factors may influence a person's decision regarding condom use or a person's compliance with safer sex practices.     

Evaluating the impact of antiretroviral therapy on HIV transmission

As global efforts proceed to scale up the delivery of antiretroviral therapy (ART) to HIV-infected persons in most urgent need, it is essential to understand the potential impact of treatment expansion on the transmission of new HIV infections. In this study, we use a series of simple mathematical models to explore the direction and magnitude of treatment effects on the sexual transmission of HIV. By defining the circumstances under which ART can reduce the number of new infections transmitted by treated patients, we provide critical benchmarks to aid in prioritizing efforts to maximize the population health impact of treatment and in evaluating the performance of different treatment programmes. We find that, based on the best currently available evidence of possible treatment effects on patient infectiousness, survival and behavior, the potential remains for either positive or negative changes in overall transmission. In relation to the total number of expected secondary infections caused by each infected person, however, these net treatment effects are relatively modest, particularly if treatment is initiated at advanced stages of the disease. This finding implies that treatment alone should not be expected to alter the population-level incidence of new infections dramatically, in the absence of changes in other factors including possible behavioral responses among uninfected persons and among infected persons who are not yet treatment candidates.     

Evaluating the potential impact of vaginal microbicides to reduce the risk of acquiring HIV in female sex workers

OBJECTIVES: The following questions were addressed: would the introduction of vaginal microbicides substantially reduce the risk of female sex workers (FSWs) acquiring HIV? Which factor would it be most important to maximize, microbicide efficacy or microbicide use? What level of microbicide efficacy and use would be necessary to counterbalance a possible reduction in condom use? DESIGN: Mathematical modeling, with parameter estimations from available literature. METHODS: Risk equations were developed and Monte Carlo simulations were performed to model a FSW's daily risk of HIV acquisition currently, and after, microbicide introduction. Uncertainty and sensitivity analyses were used as well as tornado plots for two ranges of microbicide efficacy (30-50%) and (50-80%). Risk was estimated for FSWs whose clients sometimes (10-50%) use condoms, and those whose clients never use condoms. An analytical threshold for which reducing condom use increases risk was estimated. RESULTS: For both groups of FSWs, daily risk would decrease by approximately 17% or approximately 28% using 30-50% or 50-80% effective microbicides, respectively. Increasing microbicide use would have greater impact on reducing risk than increasing microbicide efficacy. The microbicide efficacy and usage required to ensure that 'condom replacement' does not increase a FSW's risk of acquiring HIV was calculated. CONCLUSIONS: Microbicides could substantially reduce FSWs' risk of acquiring HIV; absolute decrease in risk would be greatest in high-prevalence regions. The public health impact of microbicides will depend upon usage and efficacy. Even if the microbicides that become available are only low-to-moderately effective, the probability that risk in FSWs will increase (due to replacing condoms with microbicides) is low.     

High levels of unprotected sex with men and women among men who have sex with men: a potential bridge of HIV transmission in Beijing, China.

China is experiencing an emerging HIV epidemic among men who have sex with men (MSM). We investigated sexual risk, risk perception, HIV and condom knowledge, and utilization of prevention services in the first large sample of MSM recruited in Beijing. Four hundred eighty-two MSM were sampled from September 2001 to January 2002. Forty-nine percent of participants reported unprotected anal intercourse with men during the previous 6 months. However, only 15% perceived they are at risk for HIV and many had misconceptions about HIV transmission routes and limited knowledge about condoms. Less than one quarter obtained free condoms (24%) and condom lubricants (19%) in the past 2 years. Multiple logistic regression analysis showed that unprotected insertive anal intercourse was associated with not having a Beijing residence card, having six or more male sexual partners, not having sex with women, having a lifetime history of sexually transmitted diseases (STDs), and having never tested for HIV. Unprotected receptive anal intercourse was independently associated with having six or more male sexual partners, not having sex with women, having a lifetime history of STDs, having never tested for HIV, and having less exposure to HIV prevention services. In addition, 28% reported having sex with both men and women during the previous 6 months, and 11% had unprotected intercourse with both men and women. This finding suggests that MSM are a potential bridge of HIV transmission to heterosexual women (or vice versa) and that addressing the HIV prevention needs of MSM may benefit the wider population.     

HIV transmission among gay men through oral sex and other uncommon routes: case series of HIV seroconverters, Sydney

Seventy-five homosexual men with recently acquired HIV were interviewed about their risk behaviour. Fifty-nine reported unprotected anal intercourse, and one shared injecting equipment, with a partner not known to be HIV negative. Of the remaining 15, 11 reported protected anal intercourse. In five of the 15 we judged oral sex to be the most likely source of infection, including three men who had a genital piercing. The possible transmission risk from genital piercing should be investigated.     

Orogenital sex and the transmission of HIV among homosexual men.

OBJECTIVE: To investigate the possibility of orogenital transmission of HIV. DESIGN: Cohort study on HIV infection among homosexual men. SETTING: The Municipal Health Service, Amsterdam, The Netherlands. PATIENTS, PARTICIPANTS: Homosexual men for whom the date of HIV seroconversion was known (n = 102) were included in our study. MAIN OUTCOME MEASURES: Data on the sexual behaviour of our subjects in the 6-9 months preceding HIV seroconversion were collected. In order to identify those men who consistently denied practising receptive anogenital intercourse, information was retrieved from written questionnaires and from face-to-face interviews. RESULTS: Receptive anogenital intercourse in the 6-9 months before seroconversion was denied by 20 seroconverters in their written questionnaires. However, in face-to-face interviews, 11 men later reported this sexual practice. CONCLUSIONS: Orogenital transmission of HIV appears to occur, but its frequency may be overestimated because of reluctance to report the practice of receptive anogenital intercourse.     

Venous air embolism. Life-threatening complication of orogenital sex during pregnancy

Vaginal insufflation in pregnant women leading to acute venous air embolism has been appreciated by obstetricians and pathologists for several decades. Initially described as a complication of powder insufflation for treatment of trichomonal vaginitis, insufflation-induced air embolism has been more recently associated with orogenital sex. The case herein illustrates a typical history that is almost pathognomonic. Clinical and laboratory abnormalities as well as treatment measures are briefly described. Familiarity with this syndrome is essential if prompt and appropriate therapy is to be rendered.     

Potential for HIV transmission through unsafe injections

We tested for HIV in discarded needles and syringe washes from 191 HIV-infected patients receiving injections in rural Cameroon. HIV-1 RNA was amplified from 34 of 103 intravenous injection syringes and two of 88 intramuscular injection syringes. All 36 strains were HIV-1 group M. The majority belonged to the circulating recombinant form CRF02 (IbNg). Our data support a role for unsafe injections in the spread of HIV-1 in Africa, in contrast to recent studies.     

Study: HIV diagnosis won't stop unprotected sex. Study shows prevention efforts are hindered

Research of an inner-city New York City population has showed that many of the people, particularly women, diagnosed with HIV infection continued to engage in unprotected sex after their diagnosis and prevention education. The study also found that 25% of those infected with HIV had a new sexually transmitted disease diagnosis, and 15% used injection drugs.     

分娩方式与艾滋病母婴传播

艾滋病病毒(HIV)可通过母亲妊娠分娩传播给新生儿,即艾滋病的母婴传播。艾滋病母婴传播可发生在妊娠、分娩和哺乳的各个过程,但在分娩前后的传播比例最高。分娩过程中产科因素对艾滋病母婴传播风险的影响,特别是不同分娩方式是否会影响艾滋病母婴传播风险,既往一直争议不断。近年来由于抗病毒药物特别是高效抗反转录病毒疗法和人工喂养,已将母婴传播的风险下降到一个较低的水平,越来越多的研究者已不再倾向将分娩方式选择作为减少艾滋病母婴传播的主要干预措施。