Bayesian evidence synthesis for a transmission dynamic model for HIV among men who have sex with men

Understanding infectious disease dynamics and the effect on prevalence and incidence is crucial for public health policies. Disease incidence and prevalence are typically not observed directly and increasingly are estimated through the synthesis of indirect information from multiple data sources. We demonstrate how an evidence synthesis approach to the estimation of human immunodeficiency virus (HIV) prevalence in England and Wales can be extended to infer the underlying HIV incidence. Diverse time series of data can be used to obtain yearly "snapshots" (with associated uncertainty) of the proportion of the population in 4 compartments: not at risk, susceptible, HIV positive but undiagnosed, and diagnosed HIV positive. A multistate model for the infection and diagnosis processes is then formulated by expressing the changes in these proportions by a system of differential equations. By parameterizing incidence in terms of prevalence and contact rates, HIV transmission is further modeled. Use of additional data or prior information on demographics, risk behavior change and contact parameters allows simultaneous estimation of the transition rates, compartment prevalences, contact rates, and transmission probabilities.     

The HIV epidemic among men who have sex with men—behaviour beats science

More than three decades after the emergence of HIV/AIDS, more than 30 million people worldwide still live with the disease. In the West, those most at risk are men who have sex with men owing to a combination of social factors and, ironically, improved healthcare.The acquired immune deficiency syndrome (AIDS) pandemic that started more than 30 years ago remains one of the greatest public-health concerns worldwide: in 2009, it was estimated that 33.3 million individuals were infected with human immunodeficiency virus (HIV), with 2.6 million new infections globally (see graphic; [1]). Even in the affluent countries of North America, Australia, New Zealand and Western and Central Europe, the numbers of people infected with HIV have grown over the past two decades. Although the availability of efficient diagnostics and highly active antiretroviral therapy (HAART) have drastically improved life expectancy and quality of life—at least in those parts of the world where both are available and affordable—HAART does not cure the disease. Moreover, despite massive research efforts, there is no efficient vaccine on the market to protect against infection with HIV.Given the lack of either a vaccine or a cure, the main public-health intervention to halt the pandemic is to prevent viral transmission in the first placeGiven the lack of either a vaccine or a cure, the main public-health intervention to halt the pandemic is to prevent viral transmission in the first place. In fact, the transmission of HIV is not as efficient as other, more resistant blood-borne viruses such as hepatitis B and hepatitis C viruses (HBV and HCV), and it requires direct contact of blood or semen from an infected person with the blood system of the exposed person. This feature puts certain groups at greater risk of transmission: heterosexuals with many sexual partners, including sex workers, men who have sex with men (MSM—a technical term used by health professionals to avoid forcing individuals to define themselves in a specific sexuality), people who inject drugs, newborns of HIV-infected mothers, blood recipients and healthcare workers. Yet, the risk of infection differs for each of these groups. There is also a geographical dimension to the risk, as different parts of the world have unique epidemiological characteristics, reflecting biological, behavioural and socio-economic factors. In many parts of Africa and Asia, for example, the most susceptible groups are heterosexuals and sex workers; in Eastern Europe, people who inject drugs are mainly affected; and in western countries, the most vulnerable population are MSM, followed by heterosexual migrants from areas where HIV is endemic [2].

Science & Society Series on Sex and Science

Sex is the greatest invention of all time: not only has sexual reproduction facilitated the evolution of higher life forms, it has had a profound influence on human history, culture and society. This series explores our attempts to understand the influence of sex in the natural world, and the biological, medical and cultural aspects of sexual reproduction, gender and sexual pleasure.Public-health programmes intended to prevent the transmission of HIV therefore have to address these groups individually. Such measures require education and the involvement of at-risk populations, and recommendations must be based on a thorough understanding of the social, economic and other factors that determine disease risk among certain groups of people. For instance, one of the most efficient measures to decrease the risk of HIV infection among people who inject drugs is to offer clean syringes and needles,and safe places to use them. One of the most efficient ways to prevent HIV transmission during sexual intercourse is the use of condoms. But, the answers are not always as simple; human behaviour is complex and even irrational at times. This paper outlines the main causes of the HIV epidemic among MSM in western countries, highlights specific behavioural factors that increase exposure to HIV and discusses how these can be addressed in public-health programmes.AIDS was first identified and described in the USA in June 1981 [3]. Following reports from Los Angeles and New York City about clusters of otherwise healthy Caucasian MSM who developed Kaposi''s sarcoma and fatal Pneumocystis carinii (jirovecii) pneumonia, the US Centers for Disease Control and Prevention (CDC) conducted an epidemiological investigation and identified a man they referred to as ‘patient zero'': a flight attendant working for Air Canada named Gaëtan Dugas, who had numerous male sexual partners in North America. Dugas might not have been the first person who was infected with HIV, but the first one who was identified with the disease.​disease.Open in a separate windowSee full size illustration: http://staging-www.nature.com/embor/journal/v13/n11/full/embor2012152i1.htmlIt was a combination of a general liberal attitude towards sex that was prevalent among MSM, unprotected anal sex and having multiple sexual partners that allowed HIV to spread quickly among the gay community in the early 1980s. Owing to the overwhelming impact on MSM in the early years of the AIDS epidemic—when many MSM saw close friends, partners and lovers die—gay communities adopted a range of practices to reduce the risk of infection successfully by changing sexual behaviours. Regretfully, these achievements did not last; many other developed countries also recorded a resurgence in the number of MSM newly diagnosed with HIV/AIDS since the mid-1990s [4]. The main reason for the re-emergence of the disease was the come-back of risky sexual behaviours, triggered by wider social and cultural changes, greater social acceptance for gay men and, somehow unpredictably, the introduction of more efficient drugs [5].The most important risk factor for exposure to HIV among MSM remains sexual practices. As the rectal mucosa is more fragile than the vaginal or oral, anal sex increases the risk for transmitting HIV and other sexually transmitted infections (STIs). The frequency of risky sexual practices between MSM seems to be increasing [6], which would go some way to explaining the resurgence of AIDS.Another main factor for the resurgence of AIDS among the gay communities in western countries is, ironically, the efficiency of HAARTIn addition, gay communities have a relatively liberal attitude towards sex and partnership. The way they form partnerships may differ from many heterosexuals: the sexual contact is more instantaneous and spontaneous, and sexual intercourse may take place early in a relationship [7]. Relationships between some MSM may be more flexible, and concurrent sex with casual partners during a relationship is generally more tolerable [8,9]. Concomitancy and age-mixing of sexual partners has a strong influence on the dynamic of HIV transmission if an infected man is unaware of his infection owing to the asymptomatic nature during the first years of HIV infection, or because he has not been tested for HIV [10]. Early sexual debut is another reason for greater exposure to HIV, as MSM would have more partners during their lifetime.Social changes have also played a role in increasing the HIV transmission rate among MSM. Since the 1990s, homosexuality and gay lifestyle have become much more accepted in many western societies. This increasing tolerance and acceptance has enabled many MSM ‘to get out of the closet'', that is to disclose their sexual orientation and have fulfilling lives. It has also encouraged entrepreneurs to tap into this customer base by offering services and establishments specifically for MSM including cafés, bars, clubs, restaurants, hotels and bath houses, all specifically intended for the purpose of meeting other men. This sexually liberal climate, along with the venues to meet other gay men, has amplified the risk of having sex with an HIV-infected partner.Similarly, the rise of internet-dating sites has increased the ease with which new partners can be found. New sexual practices and behavioural norms are quickly diffused between cultures, with possible international importing of HIV and other STIs. The internet, which is affordable, immediate and discrete, has become the most popular way of searching for other MSM. Most gay-related internet sites are free and guarantee anonymity until participants find the preferred fit and disclose their personal details or picture. The discrete nature of the web also allows MSM who are still ‘in the closet'' or ‘on the down low'' to search for sexual partners. This electronic meeting place might modify the sexual risk, as it exposes users to a diverse pool of men and increases their ability to search and negotiate for sexual practices [11]. The anonymity also allows MSM to search explicitly for unprotected anal sex [12]. MSM who originate from low-resource countries and migrate to developed countries might not be familiar with the risk of unprotected sex and may also be excited about the sizeable and versatile MSM community in the hosting country [12]. A combination of insufficient knowledge about HIV/AIDS, coupled with their interest in experiencing gay life, may increase the risk for those migrants to become infected with HIV.…the chances that an HIV-negative MSM finds himself engaged in sexual contact with an HIV-infected partner are higher than 15 years agoCorresponding with the increased number of sexual partners and the greater risk during sexual intercourse, MSM are also exposed to other STIs, especially if they are already infected with HIV. Increasing incidence of syphilis, as well as outbreaks of primary and secondary syphilis among MSM, has been reported during the past decade from developed countries [13,14]. Primary syphilis might manifest in a ‘chancer''—a sore—which is a possible port of entry for HIV. Additionally, the immunological reaction to STIs includes the migration of macrophages and lymphocytes to the affected organs. These cells are also the target of HIV, and thus one STI increases the chances of infection with further STIs or HIV. Over the past years, several outbreaks of lymphogranuloma venereum (an uncommon STI), presenting proctitis (inflammation of the rectum), and genital ulcers with inguinal adenopathy (inflammation of the lymph nodes in the groin) have been reported [15]. The asymptomatic nature of some STIs, along with the limited success of the risk-reduction strategies practiced by MSM, might explain the increased incidence of STIs among gay men [16,17]. Among HIV-infected individuals, genital infections with common STI pathogens have been associated with increased HIV viral load in semen, thus negating the benefit of HAART [18].Another important factor for the resurgence of AIDS among the gay communities in western countries is, ironically, the efficiency of HAART, which has converted AIDS from a death sentence into a manageable chronic medical condition. As the perceived threat of HIV/AIDS diminishes and direct experience with death disappears, some MSM may be more inclined to take higher risks. Before the introduction of HAART in the mid-1990s, most MSM had direct experience of the devastating effects of HIV/AIDS on friends and loved ones. It is important to note that HAART reduces the viral load in HIV-infected persons to undetectable levels in the blood and thereby decreases the risk of infecting partners. However, studies have documented the persistence of HIV virions and infected cells in semen of HIV-infected MSM treated with HAART [19]. Most physicians, therefore, do not recommend unprotected sex for HAART-treated HIV/AIDS patients, although the risk of HIV transmission has been significantly reduced.…public-health measures to reduce the prevalence of HIV among MSM should focus on the behavioural and psychosocial factors that increase the risk of infectionAs such, HAART has profoundly changed the impact of HIV/AIDS: people who live with HIV/AIDS who adhere to their drug regimen are usually asymptomatic and seem healthy. The non-fatal prognosis for AIDS, the large communities of HIV-infected MSM who live apparently healthy lives and the greater social acceptability of the disease have together reduced the perceived threat of HIV/AIDS.The success of HAART has affected sexual behaviour, a phenomenon called ‘AIDS optimism''. First, as HIV-infected MSM feel healthy and their sex-drive is preserved, they have a normal sex life and seek sexual partners, similarly to HIV-negative MSM. Second, before HAART and during its introduction in the 1990s, people living with HIV/AIDS could be recognized either by their cachectic posture or by the lipodystrophic features of their cheekbones and limbs due to loss of subdermal fat—a side-effect of the first generation of protease inhibitors. HIV-negative MSM could therefore decline sexual contact or insist on safer sex practices. However, modern HAART has diminished side-effects and HIV-infected men are usually unrecognizable. MSM may wrongly consider their sexual partners to be HIV-negative and might have unprotected sex. Third, some MSM may be aware of the availability of post-exposure prophylaxis as an additional use of ART, and might have unprotected sex then request the treatment, which is available up to 72 hours after sex [20]. These men may not be aware that post-exposure treatment has not been proven to be efficient in humans in randomized clinical trials. Finally, young MSM, who have not witnessed the devastation of AIDS, may no longer feel threatened by the disease and might engage in unprotected sex. The advanced manageability of HIV, as portrayed in the media and advertisements sponsored by the pharmaceutical industry, may further disinhibit their sexual behaviour.Moreover, the success of HAART and decades of public-health recommendations to practice safe sex may have led to ‘AIDS fatigue''. Some MSM may become desensitized to safe-sex messages and might develop a negative emotional response to HIV issues. As the number of newly diagnosed HIV-positive MSM is increasing, some will also remain unaware of their infection and may ignore safe-sex practices. Thus, the chances that an HIV-negative MSM finds himself engaged in sexual contact with an HIV-infected partner are higher than 15 years ago. Some public-health professionals argue that the uptake of HIV tests among MSM has more to do with the increased acceptance of their lifestyle than an increasing infection rate; thus the high HIV rates recorded are no more than epidemiological fallacy. However, even if this assumption is true, it neither explains the rapid dynamic of HIV transmission among MSM communities, nor the increased syphilis infection rates. Additionally, ART-resistant strains of HIV have emerged, which complicates treatment and prolongs the transmission period. The prevalence of primary or transmitted drug-resistant HIV strains in North America and Western Europe is as high as 26% [21].…it crucially requires the involvement and engagement of the gay community themselves to maintain effective and acceptable interventionsDrug abuse is another relevant risk factor. Even if the percentage of intravenous drug users among MSM may not differ compared with the percentage among heterosexuals, it creates a twofold risk of acquiring HIV: by blood-to-blood transmission when sharing needles and syringes, and by semen-to-blood exposure when having sex. Some males who inject drugs may also engage in sex with other males, although they are heterosexuals, to finance their addiction.MSM are generally aware of their risk of acquiring HIV and of the importance of condom use. Yet, they have developed alternative strategies to prevent possible HIV exposure that involve evaluating their partners and the environment in which they meet more carefully, and then taking calculated risks [22]. One such strategy used is called ‘negotiated safety'', in which both men disclose to each other their HIV status before they have sexual intercourse and may decide to perform unprotected anal sex if they are both negative. The efficacy of this strategy depends on the time at which they were tested, their honesty and being safe if performing sex outside the primary sexual relationship. The second strategy is ‘sero-sorting'', when MSM restrict unprotected anal intercourse only to partners they believe to be concordant [23]. MSM negotiate and try to identify signs that might indicate that a partner could be HIV-positive, such as special physical features—being cachectic or lypodystrophic—the venue and context in which they meet, and when visiting the home of a partner, taking a quick look in their drawers or in the bathroom closet to search for HAART tablets (‘sero-guessing''). Another strategy is called ‘strategic positioning'', which is the use of sero-status to determine sexual roles in which MSM may perform only oral sex or take the active role in anal sex. However, these risk reduction strategies, widely used by MSM, offer only limited protection from HIV [24].The recommended use of condoms during anal sex can fall by the wayside after recreational drug use. Drugs such as alcohol and methamphetamine, which are commonly used at clubs, discos and other venues, lower social barriers and increase sociability. MSM using such drugs are therefore more inclined to have sex with an unknown partner and might not use a condom, as their judgment is impaired. This risky combination of drug use during sexual contact is called ‘party and play'' on internet sites for MSM who are searching for a partner [25].The result is that in the post-HAART era, MSM still remain the group most at risk of acquiring HIV, with substantial evidence for continuing HIV transmission. It has been estimated that more than 40% of HIV-positive young MSM are involved in risky sexual behaviour, despite their awareness of their infection [26,27]. Behavioural, emotional, psychological, environmental and epidemiological factors all act synergistically to increase risk-taking when it comes to sexual practices, thus exacerbating HIV incidence in MSM. These factors might be even more dominant among HIV-positive MSM, driving them to perform unprotected anal sex. They face specific psychosocial factors such as the need to be loved and cared for, a different meaning of sex as an emotional connection and a decreased desire for intimacy after their diagnosis, owing to mixed feelings of shame and guilt [24].By contrast, HIV-infected MSM who receive HAART and achieve undetectable viral load in their blood usually reduce the risk of transmitting the virus to their sexual contacts, and probably engage less in risky sexual behaviour than those who are not on ART [28]. One explanation is that they frequent HIV clinics more often and are therefore more aware of the need to use condoms, and receive positive self-care advice. Some studies have shown that many HIV-positive men are also engaged in both sero-sorting and strategic positioning, probably to avoid HIV transmission to members of their social and sexual networks [29].…the success of HAART and decades of public-health recommendations to practice safe sex might have led to ‘AIDS fatigue''Some HIV-infected MSM therefore prefer to contact sero-concordant HIV-positive partners to experience unprotected anal intercourse, free from the worry of infecting a negative partner, or the embarrassment of having to disclose their HIV status to a negative partner, exposing themselves to the stigma attached to HIV. These perceived benefits seem to outweigh the perceived risks of contracting another strain of HIV, potentially drug-resistant, or STIs.Lacking an efficient vaccine or cure for AIDS, public-health measures to reduce the prevalence of HIV among MSM should focus on the behavioural and psychosocial factors that increase the risk of infection. Effectively, this means educational and outreach campaigns to address risky sexual behaviour and to promote the use of condoms and other protective strategies. These interventions should involve all relevant parties: non-governmental and governmental organizations, health providers, public-health experts and gay-related agencies. The message about the continuing risks and dangers of HIV/AIDS should go through multiple routes to address as many men as possible through the internet, media, clubs, bars and public spaces, to reinforce consistent condom use and other risk-reduction strategies, and to promote early diagnosis and treatment.Such campaigns should address both HIV-negative and HIV-positive men, but with a different focus on the needs of each. HIV-negative MSM should be informed about the possible routes of HIV transmission, the importance of using condoms, improving negotiation skills and other risk-reduction strategies to protect themselves and their partners. Innovative interventions could also attempt to associate the strong motivation of MSM for masculinity with the use of condoms. Additionally, frequent HIV testing in MSM-friendly clinics and community settings should be encouraged to detect new infections as early as possible. HIV-infected MSM should be instructed with safe-sex recommendations and prescribed HAART to reduce seminal viral load. Intervention in this group should address the unique psychological, social and medical status of each patient. As pointed out above, it crucially requires the involvement and engagement of the gay community themselves to maintain effective and acceptable interventions.Health educators must also respect the needs, wishes and behaviour of MSM when addressing them about the risk of HIV/AIDS, and making recommendations about safe-sex practices. Although condoms are indeed efficient at preventing HIV transmission, they might nonetheless be the ‘incorrect'' instrument in the ‘wrong'' place for many people. Condom use breaks the intimacy and spontaneity of sex and reduces the pleasure. Although we hope that we can convince a young, HIV-positive MSM to use condoms, this might not be a realistic goal. As such, addressing the risks requires a sensitive, ‘down-to-earth'' approach that respects gay culture and the dynamic of finding partners, as well as training physicians to provide counselling for MSM in a friendly and confident way.Reducing the use of illicit drugs in both HIV-infected and uninfected MSM is another priority, although in some cases drugs are used to cope with the stress related to living with HIV. Appropriate interventions for HIV-infected MSM must therefore include stress-reduction techniques, psychological services and counselling about the negative effects of substance use. Another public-health priority is to promote the disclosure of HIV status as part of the ethics related to using gay-dating sites. As the perceived threat of HIV has diminished owing to the success of ART and the non-fatal medical prognosis of HIV/AIDS, noticeable messages should be more positive and reflect contemporary gay life, using gay-related and non-gay-related venues frequented by MSM, such as gyms, airports, shops or tourist resorts.To address the problem and slow or halt the pandemic requires focused, evidence-based measures that respect biological, emotional and social aspects in a holistic approach…In conclusion, HIV prevalence among MSM remains high and, given the increase in survival of HIV-infected individuals and the high rate of new infections, this hyper-endemic state is likely to be sustained in developed countries [14]. To address the problem and slow or halt the pandemic requires focused, evidence-based measures that respect biological, emotional and social aspects in a holistic approach [24], taking into account psychological stressors, drug habits, discrimination and the quest for intimacy. It is also important to increase the sensitivity of health providers towards the special needs of MSM, to conduct open and non-judgemental discussions with their patients. A supportive medical environment can encourage MSM to adhere to periodical HIV testing, HBV and hepatitis A virus immunizations and, possibly, to comply with condom use [19]. Finally, due to the similarities in MSM behaviours in industrialized countries, a closer collaboration is required between researchers from countries that have large MSM communities. We are entering the fourth decade of the AIDS epidemic, and despite awareness among MSM of their greater vulnerability to HIV and the introduction of new medical interventions, the rate of new infections continues to rise disproportionately. It is time for new interventions.? Open in a separate windowZohar MorOpen in a separate windowMichael Dan     

Assessing the drivers of syphilis among men who have sex with men in Switzerland reveals a key impact of screening frequency: A modelling study

Over the last decade, syphilis diagnoses among men-who-have-sex-with-men (MSM) have strongly increased in Europe. Understanding the drivers of the ongoing epidemic may aid to curb transmissions. In order to identify the drivers of syphilis transmission in MSM in Switzerland between 2006 and 2017 as well as the effect of potential interventions, we set up an epidemiological model stratified by syphilis stage, HIV-diagnosis, and behavioral factors to account for syphilis infectiousness and risk for transmission. In the main model, we used ‘reported non-steady partners’ (nsP) as the main proxy for sexual risk. We parameterized the model using data from the Swiss HIV Cohort Study, Swiss Voluntary Counselling and Testing center, cross-sectional surveys among the Swiss MSM population, and published syphilis notifications from the Federal Office of Public Health. The main model reproduced the increase in syphilis diagnoses from 168 cases in 2006 to 418 cases in 2017. It estimated that between 2006 and 2017, MSM with HIV diagnosis had 45.9 times the median syphilis incidence of MSM without HIV diagnosis. Defining risk as condomless anal intercourse with nsP decreased model accuracy (sum of squared weighted residuals, 378.8 vs. 148.3). Counterfactual scenarios suggested that increasing screening of MSM without HIV diagnosis and with nsP from once every two years to twice per year may reduce syphilis incidence (at most 12.8% reduction by 2017). Whereas, increasing screening among MSM with HIV diagnosis and with nsP from once per year to twice per year may substantially reduce syphilis incidence over time (at least 63.5% reduction by 2017). The model suggests that reporting nsP regardless of condom use is suitable for risk stratification when modelling syphilis transmission. More frequent screening of MSM with HIV diagnosis, particularly those with nsP may aid to curb syphilis transmission.     

我国男男性行为人群中人类免疫缺陷病毒感染疫情特点及防治策略

目前我国人类免疫缺陷病毒（HIV）感染疫情总体处于低流行水平,但男男性行为（MSM）人群中HIV感染呈现快速上升趋势,传播亚型呈现出新的特点,疾病进展较快。HIV核酸及抗原抗体检测等手段对早期发现MSM人群中HIV感染者具有重要意义。解析MSM人群艾滋病疾病进展的影响因素,发现新的生物学标记,可为早期评估HIV感染的预后提供创新性手段。早期发现我国MSM人群中HIV感染者和抗病毒治疗等综合干预,对我国艾滋病流行的控制具有重要意义。     

HIV incidence among men who have sex with men in China: a meta-analysis of published studies

Background

Men who have sex with men (MSM) have now become one of the priority populations for prevention and control of HIV pandemic in China. Information of HIV incidence among MSM is important to describe the spreading of the infection and predict its trends in this population. We reviewed the published literature on the incidence of HIV infection among MSM in China.

Methods

We identified relevant studies by use of a comprehensive strategy including searches of Medline and two Chinese electronic publication databases from January 2005 to September 2010. Point estimate of random effects incidence with corresponding 95% confidence intervals (CI) of HIV infection was carried out using the Comprehensive Meta-Analysis software. Subgroup analyses were examined separately, stratified by study design and geographic location.

Results

Twelve studies were identified, including three cohort studies and nine cross-sectional studies. The subgroup analyses revealed that the sub-overall incidence estimates were 3.5% (95% CI, 1.7%–5.3%) and 6.7% (95% CI, 4.8%–8.6%) for cohort and cross-sectional studies, respectively (difference between the sub-overalls, Q = 5.54, p = 0.02); and 8.3% (95% CI, 6.9%–9.7%) and 4.6% (95% CI, 2.4%–6.9%) for studies in Chongqing and other areas, respectively (difference between the sub-overalls, Q = 7.58, p<0.01). Syphilis infection (RR = 3.33, p<0.001), multiple sex partnerships (RR = 2.81, p<0.001), and unprotected receptive anal intercourse in the past six months (RR = 3.88, p = 0.007) represented significant risk for HIV seroconversion.

Conclusions

Findings from this meta-analysis indicate that HIV incidence is substantial in MSM in China. High incidence of HIV infection and unique patterns of sexual risk behaviors in this population serve as a call for action that should be answered with the innovative social and public health intervention strategies, and development of biological prevention strategies.     

A characterization of internet dating network structures among nordic men who have sex with men

Background

The Internet has become an important venue for seeking sexual partners and may facilitate transmission of sexually transmitted infections.

Methods

We examined a 64-day data log of flirt messages expressing sexual interest among MSM within the Qruiser.com community. We used logistic regression to analyze characteristics of MSM sending and receiving flirt messages and negative binomial regression to examine individual activity and popularity. The structural properties, including the core structure of the flirt network, were analyzed.

Results

The MSM population consisted of approximately 40% homosexuals and 37% bisexuals, while the remaining 23% included men who identified as heterosexual but searched for sex with men and “experimental”. MSM were more likely to send flirt messages if they were homosexual and aged 40+ years; young people aged < 30 years were more likely to receive a flirt. Possession of a webcam was strongly associated with both sending flirt messages and being a flirt target. The distributions of flirts sent (max k_out = 2162) and received (max k_in = 84) were highly heterogeneous. Members in central cores were more likely homosexuals, singles, and aged 31–40 years. The probability of a matched flirt (flirt returned from target) increased from 1% in the outer core to 18% in the central core (core size = 4).

Discussion

The flirt network showed high degree heterogeneity similar to the structural properties of real sexual contact networks with a single central core. Further studies are needed to explore use of webcam for Internet dating.     

A baseline epidemiological study of the co-infection of enteric protozoans with human immunodeficiency virus among men who have sex with men from Northeast China

BackgroundHuman immunodeficiency virus (HIV) and enteric parasite co-infection not only aggravates the clinical symptoms of parasites but also accelerates acquired immunodeficiency syndrome (AIDS) progression. However, co-infection research on men who have sex with men (MSM), the predominant high-risk population of HIV/AIDS in China, is still limited. In this study, we investigated the epidemiology of enteric parasites, risk factors, and associations with clinical significance in an MSM HIV/AIDS population in Heilongjiang Province, northeast China.MethodsWe recruited 308 MSMs HIV/AIDS patients and 199 HIV-negative individuals in two designated AIDS hospitals in Heilongjiang between April 2016 and July 2017. Fresh stool samples were collected. DNA extraction, molecular identification, and genotyping of Cryptosporidium species, Entamoeba histolytica, Cyclospora cayetanensis, Enterocytozoon bieneusi, and Blastocystis hominis were performed. Fourteen diarrhea-related pathogens were examined to exclude the influence of other bacterial pathogens on diarrhea incidence.Results31.5% of MSM HIV/AIDS participants were infected with at least one parasite species, a significantly higher proportion than that found in the HIV-negative individuals (2.5%). E. bieneusi presented the highest prevalence, followed by B. hominis, E. histolytica, Cryptosporidium spp., and C. cayetanensis. Warm seasons were the risk factor for parasitic infections in this population [odds ratio (OR) = 2.6, 95% CI: 1.47–4.57]. In addition, these individuals showed a higher proportion (35.8%) of present diarrhea (PD) compared with men who have sex with women (MSW) with HIV/AIDS (16.7%). The infection proportions of both Cryptosporidium spp. and E. histolytica were significantly higher in the PD. E. bieneusi infection was more prevalent in the historic diarrhea (HD) group. CD4⁺ T cell counts in the MSM patients with the above three parasites were significantly lower. New species and genotypes were found, and MSM patients had a wider range of species or genotypes.ConclusionsEnteric parasitic infection was prevalent in the MSM HIV/AIDS population, especially in patients with present diarrhea during warm seasons. E. histolytica and B. hominis should also be considered high-risk parasites for opportunistic infections in AIDS patients in addition to Cryptosporidium spp.     

HIV and syphilis co-infection increasing among men who have sex with men in China: a systematic review and meta-analysis

Background

This study aims to estimate the magnitude and changing trends of HIV, syphilis and HIV-syphilis co-infections among men who have sex with men (MSM) in China during 2003–2008 through a systematic review of published literature.

Methodology/Principal Findings

Chinese and English literatures were searched for studies reporting HIV and syphilis prevalence among MSM from 2003 to 2008. The prevalence estimates were summarized and analysed by meta-analyses. Meta-regression was used to identify the potential factors that are associated with high heterogeneities in meta-analysis. Seventy-one eligible articles were selected in this review (17 in English and 54 in Chinese). Nationally, HIV prevalence among MSM increased from 1.3% during 2003–2004 to 2.4% during 2005–2006 and to 4.7% during 2007–2008. Syphilis prevalence increased from 6.8% during 2003–2004 to 10.4% during 2005–2006 and to 13.5% during 2007–2008. HIV-syphilis co-infection increased from 1.4% during 2005–2006 to 2.7% during 2007–2008. Study locations and study period are the two major contributors of heterogeneities of both HIV and syphilis prevalence among Chinese MSM.

Conclusions/Significance

There have been significant increases in HIV and syphilis prevalence among MSM in China. Scale-up of HIV and syphilis screening and implementation of effective public health intervention programs should target MSM to prevent further spread of HIV and syphilis infection.     

Hepatitis B,C, and D virus and human T-cell leukemia virus types 1 and 2 infections and correlates among men who have sex with men in Ouagadougou,Burkina Faso

Background

Men who have sex with men (MSM) are considered to be at significant risk for sexually transmitted infections (STI) and bloodborne viruses including viral hepatitis types B, C, and D (HBV, HCV, and HDV) and human T-cell leukemia virus types 1 and 2 (HTLV 1&2). This study aimed to assess the seroprevalence and correlates of HBV, HCV, HDV, and HTLV 1&2 antibodies among MSM in Ouagadougou, Burkina Faso.

Methods

We conducted a cross-sectional survey to assess the biological and behavourial characteristics among MSM in Ouagadougou from January to April 2013. Serum specimens obtained were tested for the presence of HBV, HCV, HDV and HTLV-1&2 infections. MSM 18?years and older were recruited using respondent driven sampling (RDS). Population estimates and 95% confidence intervals (CI) adjusted for the RDS design were calculated using RDS Analysis Tool (RDSAT) version 6.0.1 (RDS, Inc., Ithaca, NY). Bivariate and multivariate logistic regression analyses were conducted to assess correlates of these infections using Stata 14.

Results

A total of 329 MSM were tested. Prevalence was 20.4% (95% CI: 16.4–25.1) for HBV, 11.0% (95% CI: 8.0–14.8) for HCV, and 0.0% for HDV. Anti-HTLV 1&2 antibodies were found in 4.0% (95% CI: 2.3–6.8) of MSM. Factors independently associated with HBV infection were lack of condom use during the last anal sex act with a main male sexual partner and experience of condom tearing during anal sex. Presence of anti-HTLV 1&2 antibodies was associated with history of genital or anal lesions and injection drug use. None of the variables included in our study were associated with HCV.

Conclusions

This study shows that HBV, HCV and HTLV 1&2 prevalence among MSM in Burkina is high and suggests that comprehensive STI prevention and sexual health education services for this group are needed.

     

Biomarker-based HIV incidence in a community sample of men who have sex with men in Paris, France

BACKGROUND: Population-based estimates of HIV incidence in France have revealed that men who have sex with men (MSM) are the most affected population and contribute to nearly half of new infections each year. We sought to estimate HIV incidence among sexually active MSM in Paris gay community social venues. METHODOLOGY/ PRINCIPAL FINDINGS: A cross-sectional survey was conducted in 2009 in a sample of commercial venues such as bars, saunas and backrooms. We collected a behavioural questionnaire and blood sample. Specimens were tested for HIV infection and positive specimens then tested for recent infection by the enzyme immunoassay for recent HIV-1 infection (EIA-RI). We assessed the presence of antiretroviral therapy among infected individuals to rule out treated patients in the algorithm that determined recent infection. Biomarker-based cross-sectional incidence estimates were calculated. We enrolled 886 MSM participants among which 157 (18%) tested HIV positive. In positive individuals who knew they were infected, 75% of EIA-RI positive results were due to ART. Of 157 HIV positive specimens, 15 were deemed to be recently infected. The overall HIV incidence was estimated at 3.8% person-years (py) [95%CI: 1.5-6.2]. Although differences were not significant, incidence was estimated to be 3.5% py [0.1-6.1] in men having had a negative HIV test in previous year and 4.8% py [0.1-10.6] in men having had their last HIV test more than one year before the survey, or never tested. Incidence was estimated at 4.1% py [0-8.3] in men under 35 years and 2.5% py [0-5.4] in older men. CONCLUSIONS/ SIGNIFICANCE: This is the first community-based survey to estimate HIV incidence among MSM in France. It includes ART detection and reveals a high level of HIV transmission in sexually active individuals, despite a high uptake of HIV testing. These data call for effective prevention programs targeting MSM engaged in high-risk behaviours.     

A mathematical model of comprehensive test-and-treat services and HIV incidence among men who have sex with men in the United States

Background

Early diagnosis and treatment of HIV infection and suppression of viral load are potentially powerful interventions for reducing HIV incidence. A test-and-treat strategy may have long-term effects on the epidemic among urban men who have sex with men (MSM) in the United States and may achieve the 5-year goals of the 2010 National AIDS Strategy that include: 1) lowering to 25% the annual number of new infections, 2) reducing by 30% the HIV transmission rate, 3) increasing to 90% the proportion of persons living with HIV infection who know their HIV status, 4) increasing to 85% the proportion of newly diagnosed patients linked to clinical care, and 5) increasing by 20% the proportion of HIV-infected MSM with an undetectable HIV RNA viral load.

Methods and Findings

We constructed a dynamic compartmental model among MSM in an urban population (based on New York City) that projects new HIV infections over time. We compared the cumulative number of HIV infections in 20 years, assuming current annual testing rate and treatment practices, with new infections after improvements in the annual HIV testing rate, notification of test results, linkage to care, initiation of antiretroviral therapy (ART) and viral load suppression. We also assessed whether five of the national HIV prevention goals could be met by the year 2015. Over a 20-year period, improvements in test-and-treat practice decreased the cumulative number of new infections by a predicted 39.3% to 69.1% in the urban population based on New York City. Institution of intermediate improvements in services would be predicted to meet at least four of the five goals of the National HIV/AIDS Strategy by the 2015 target.

Conclusions

Improving the five components of a test-and-treat strategy could substantially reduce HIV incidence among urban MSM, and meet most of the five goals of the National HIV/AIDS Strategy.     

Elevated risk for HIV infection among men who have sex with men in low- and middle-income countries 2000-2006: a systematic review

Background

Recent reports of high HIV infection rates among men who have sex with men (MSM) from Asia, Africa, Latin America, and the former Soviet Union (FSU) suggest high levels of HIV transmission among MSM in low- and middle-income countries. To investigate the global epidemic of HIV among MSM and the relationship of MSM outbreaks to general populations, we conducted a comprehensive review of HIV studies among MSM in low- and middle-income countries and performed a meta-analysis of reported MSM and reproductive-age adult HIV prevalence data.

Methods and Findings

A comprehensive review of the literature was conducted using systematic methodology. Data regarding HIV prevalence and total sample size was sequestered from each of the studies that met inclusion criteria and aggregate values for each country were calculated. Pooled odds ratio (OR) estimates were stratified by factors including HIV prevalence of the country, Joint United Nations Programme on HIV/AIDS (UNAIDS)–classified level of HIV epidemic, geographic region, and whether or not injection drug users (IDUs) played a significant role in given epidemic. Pooled ORs were stratified by prevalence level; very low-prevalence countries had an overall MSM OR of 58.4 (95% CI 56.3–60.6); low-prevalence countries, 14.4 (95% CI 13.8–14.9); and medium- to high-prevalence countries, 9.6 (95% CI 9.0–10.2). Significant differences in ORs for HIV infection among MSM in were seen when comparing low- and middle-income countries; low-income countries had an OR of 7.8 (95% CI 7.2–8.4), whereas middle-income countries had an OR of 23.4 (95% CI 22.8–24.0). Stratifying the pooled ORs by whether the country had a substantial component of IDU spread resulted in an OR of 12.8 (95% CI 12.3–13.4) in countries where IDU transmission was prevalent, and 24.4 (95% CI 23.7–25.2) where it was not. By region, the OR for MSM in the Americas was 33.3 (95% CI 32.3–34.2); 18.7 (95% CI 17.7–19.7) for Asia; 3.8 (95% CI 3.3–4.3) for Africa; and 1.3 (95% CI 1.1–1.6) for the low- and middle-income countries of Europe.

Conclusions

MSM have a markedly greater risk of being infected with HIV compared with general population samples from low- and middle-income countries in the Americas, Asia, and Africa. ORs for HIV infection in MSM are elevated across prevalence levels by country and decrease as general population prevalence increases, but remain 9-fold higher in medium–high prevalence settings. MSM from low- and middle-income countries are in urgent need of prevention and care, and appear to be both understudied and underserved.     

Monetary incentives and peer referral in promoting secondary distribution of HIV self-testing among men who have sex with men in China: A randomized controlled trial

BackgroundDigital network–based methods may enhance peer distribution of HIV self-testing (HIVST) kits, but interventions that can optimize this approach are needed. We aimed to assess whether monetary incentives and peer referral could improve a secondary distribution program for HIVST among men who have sex with men (MSM) in China.Methods and findingsBetween October 21, 2019 and September 14, 2020, a 3-arm randomized controlled, single-blinded trial was conducted online among 309 individuals (defined as index participants) who were assigned male at birth, aged 18 years or older, ever had male-to-male sex, willing to order HIVST kits online, and consented to take surveys online. We randomly assigned index participants into one of the 3 arms: (1) standard secondary distribution (control) group (n = 102); (2) secondary distribution with monetary incentives (SD-M) group (n = 103); and (3) secondary distribution with monetary incentives plus peer referral (SD-M-PR) group (n = 104). Index participants in 3 groups were encouraged to order HIVST kits online and distribute to members within their social networks. Members who received kits directly from index participants or through peer referral links from index MSM were defined as alters. Index participants in the 2 intervention groups could receive a fixed incentive ($3 USD) online for the verified test result uploaded to the digital platform by each unique alter. Index participants in the SD-M-PR group could additionally have a personalized peer referral link for alters to order kits online. Both index participants and alters needed to pay a refundable deposit ($15 USD) for ordering a kit. All index participants were assigned an online 3-month follow-up survey after ordering kits. The primary outcomes were the mean number of alters motivated by index participants in each arm and the mean number of newly tested alters motivated by index participants in each arm. These were assessed using zero-inflated negative binomial regression to determine the group differences in the mean number of alters and the mean number of newly tested alters motivated by index participants. Analyses were performed on an intention-to-treat basis. We also conducted an economic evaluation using microcosting from a health provider perspective with a 3-month time horizon. The mean number of unique tested alters motivated by index participants was 0.57 ± 0.96 (mean ± standard deviation [SD]) in the control group, compared with 0.98 ± 1.38 in the SD-M group (mean difference [MD] = 0.41),and 1.78 ± 2.05 in the SD-M-PR group (MD = 1.21). The mean number of newly tested alters motivated by index participants was 0.16 ± 0.39 (mean ± SD) in the control group, compared with 0.41 ± 0.73 in the SD-M group (MD = 0.25) and 0.57 ± 0.91 in the SD-M-PR group (MD = 0.41), respectively. Results indicated that index participants in intervention arms were more likely to motivate unique tested alters (control versus SD-M: incidence rate ratio [IRR = 2.98, 95% CI = 1.82 to 4.89, p-value < 0.001; control versus SD-M-PR: IRR = 3.26, 95% CI = 2.29 to 4.63, p-value < 0.001) and newly tested alters (control versus SD-M: IRR = 4.22, 95% CI = 1.93 to 9.23, p-value < 0.001; control versus SD-M-PR: IRR = 3.49, 95% CI = 1.92 to 6.37, p-value < 0.001) to conduct HIVST. The proportion of newly tested testers among alters was 28% in the control group, 42% in the SD-M group, and 32% in the SD-M-PR group. A total of 18 testers (3 index participants and 15 alters) tested as HIV positive, and the HIV reactive rates for alters were similar between the 3 groups. The total costs were $19,485.97 for 794 testers, including 450 index participants and 344 alter testers. Overall, the average cost per tester was $24.54, and the average cost per alter tester was $56.65. Monetary incentives alone (SD-M group) were more cost-effective than monetary incentives with peer referral (SD-M-PR group) on average in terms of alters tested and newly tested alters, despite SD-M-PR having larger effects. Compared to the control group, the cost for one more alter tester in the SD-M group was $14.90 and $16.61 in the SD-M-PR group. For newly tested alters, the cost of one more alter in the SD-M group was $24.65 and $49.07 in the SD-M-PR group. No study-related adverse events were reported during the study. Limitations include the digital network approach might neglect individuals who lack internet access.ConclusionsMonetary incentives alone and the combined intervention of monetary incentives and peer referral can promote the secondary distribution of HIVST among MSM. Monetary incentives can also expand HIV testing by encouraging first-time testing through secondary distribution by MSM. This social network–based digital approach can be expanded to other public health research, especially in the era of the Coronavirus Disease 2019 (COVID-19).Trial registrationChinese Clinical Trial Registry (ChiCTR) ChiCTR1900025433

Yi Zhou and colleagues investigate whether monetary incentives and peer referral could improve a secondary distribution program for HIV self-testing among men who have sex with men in China.     

Higher viral load and genetic diversity of HIV‐1 in seminal compartments than in blood of seven Chinese men who have sex with men and have early HIV‐1 infection

To date, there have been no reports characterizing HIV‐1 in the semen of Chinese men who have sex with men (MSM) with early infection. In this study, genetic diversity and viral load of HIV‐1 in the seminal compartments and blood of Chinese MSM with early HIV‐1 infection were examined. Viral load and genetic diversity of HIV‐1 in paired samples of semen and blood were analyzed in seven MSM with early HIV‐1 infection. HIV‐1 RNA and DNA were quantitated by real‐time PCR assays. Through sequencing the C2‐V5 region of the HIV‐1 env gene, the HIV‐1 genotype and genetic diversity based on V3 loop amino acid sequences were determined by using Geno2pheno and PSSM programs co‐receptor usage. It was found that there was more HIV‐1 RNA in seminal plasma than in blood plasma and total, and more 2‐LTR circular and integrated HIV‐1 DNA in seminal cells than in peripheral blood mononuclear cells from all seven patients with early HIV‐infection. There was also greater HIV‐1 genetic diversity in seminal than in blood compartments. HIV‐1 in plasma displayed higher genetic diversity than in cells from the blood and semen. In addition, V3 loop central motifs, which present some key neutralizing antibody epitopes, varied between blood and semen. Thus, virological characteristics in semen may be more representative when evaluating risk of transmission in persons with early HIV infection.

     

Current guidelines have limited applicability to patients with comorbid conditions: a systematic analysis of evidence-based guidelines

Background

Guidelines traditionally focus on the diagnosis and treatment of single diseases. As almost half of the patients with a chronic disease have more than one disease, the applicability of guidelines may be limited. The aim of this study was to assess the extent that guidelines address comorbidity and to assess the supporting evidence of recommendations related to comorbidity.

Methodology/Principal Findings

We conducted a systematic analysis of evidence-based guidelines focusing on four highly prevalent chronic conditions with a high impact on quality of life: chronic obstructive pulmonary disease, depressive disorder, diabetes mellitus type 2, and osteoarthritis. Data were abstracted from each guideline on the extent that comorbidity was addressed (general comments, specific recommendations), the type of comorbidity discussed (concordant, discordant), and the supporting evidence of the comorbidity-related recommendations (level of evidence, translation of evidence). Of the 20 guidelines, 17 (85%) addressed the issue of comorbidity and 14 (70%) provided specific recommendations on comorbidity. In general, the guidelines included few recommendations on patients with comorbidity (mean 3 recommendations per guideline, range 0 to 26). Of the 59 comorbidity-related recommendations provided, 46 (78%) addressed concordant comorbidities, 8 (14%) discordant comorbidities, and for 5 (8%) the type of comorbidity was not specified. The strength of the supporting evidence was moderate for 25% (15/59) and low for 37% (22/59) of the recommendations. In addition, for 73% (43/59) of the recommendations the evidence was not adequately translated into the guidelines.

Conclusions/Significance

Our study showed that the applicability of current evidence-based guidelines to patients with comorbid conditions is limited. Most guidelines do not provide explicit guidance on treatment of patients with comorbidity, particularly for discordant combinations. Guidelines should be more explicit about the applicability of their recommendations to patients with comorbidity. Future clinical trials should also include patients with the most prevalent combinations of chronic conditions.     

Identification of asymptomatic Entamoeba histolytica infection by a serological screening test: A cross-sectional study of an HIV-negative men who have sex with men cohort in Japan

BackgroundAmebiasis, caused by Entamoeba histolytica, is spreading in developing countries and in many developed countries as a sexually transmitted infection. Here, we evaluated the efficacy of serological screening to identify asymptomatic E. histolytica infection as a potential epidemiological control measure to limit its spread.Methodology/Principal findingsThis cross-sectional study was carried out between January and March 2021 in an HIV-negative men who have sex with men (MSM) cohort at the National Center for Global Health and Medicine. Serological screening was performed using a commercially available ELISA kit. For seropositive individuals, we performed stool polymerase chain reaction (PCR) to determine current E. histolytica infection. We performed E. histolytica serological screening of 312 participants. None had a history of E. histolytica infection prior to the study. The overall E. histolytica seropositivity was 6.7% (21/312), which was similar to that found by the rapid plasma reagin test (17/312). We identified current infection in 8 of 20 seropositive participants (40.0%) by stool PCR.Conclusions/SignificanceOur serological screening approach constitutes a potentially practical epidemiological strategy. Active epidemiological surveys, in combination with an effective screening strategy for asymptomatically infected individuals, should be applied to help reduce sexually transmitted E. histolytica infections.     

Use of respondent driven sampling (RDS) generates a very diverse sample of men who have sex with men (MSM) in Buenos Aires, Argentina

Background

Prior research focusing on men who have sex with men (MSM) conducted in Buenos Aires, Argentina, used convenience samples that included mainly gay identified men. To increase MSM sample representativeness, we used Respondent Driven Sampling (RDS) for the first time in Argentina. Using RDS, under certain specified conditions, the observed estimates for the percentage of the population with a specific trait are asymptotically unbiased. We describe, the diversity of the recruited sample, from the point of view of sexual orientation, and contrast the different subgroups in terms of their HIV sexual risk behavior.

Methodology

500 MSM were recruited using RDS. Behavioral data were collected through face-to-face interviews and Web-based CASI.

Conclusion

In contrast with prior studies, RDS generated a very diverse sample of MSM from a sexual identity perspective. Only 24.5% of participants identified as gay; 36.2% identified as bisexual, 21.9% as heterosexual, and 17.4% were grouped as “other.” Gay and non-gay identified MSM differed significantly in their sexual behavior, the former having higher numbers of partners, more frequent sexual contacts and less frequency of condom use. One third of the men (gay, 3%; bisexual, 34%, heterosexual, 51%; other, 49%) reported having had sex with men, women and transvestites in the two months prior to the interview. This population requires further study and, potentially, HIV prevention strategies tailored to such diversity of partnerships. Our results highlight the potential effectiveness of using RDS to reach non-gay identified MSM. They also present lessons learned in the implementation of RDS to recruit MSM concerning both the importance and limitations of formative work, the need to tailor incentives to circumstances of the less affluent potential participants, the need to prevent masking, and the challenge of assessing network size.     

Association of anal symptoms with anal high grade squamous intraepithelial lesions (HSIL) among men who have sex with men: Baseline data from the study of the prevention of anal cancer (SPANC)

BackgroundThe association between anal high-grade squamous intraepithelial lesion (HSIL) and anal symptoms has not been systematically investigated.MethodsThe Study of Prevention of Anal Cancer is a prospective cohort study of men who have sex with men (MSM) ≥ 35 years old in Sydney, Australia. Self-reported symptoms were collected. Anal cytology and high-resolution anoscopy were undertaken. Using baseline visit data, men negative for squamous intra-epithelial lesion (SIL) were compared with men diagnosed with composite-HSIL (cytology and/or histology). Logistic regression analyses were performed to assess the association of symptoms with HSIL.ResultsAmong 414 MSM included (composite-HSIL (n = 231); negative for SIL (n = 183)), 306 (73.9%) reported symptom(s) within the last 6 months. There was no association between any symptom and composite-HSIL. A significant association between anal lump and a larger burden of HSIL (at least 2 intra-anal octants) (anal lump within last month: p = 0.014; anal lump within last 6 months: p = 0.010) became non-significant after adjusting for HIV-status and recent anal warts (anal lump within last month: p = 0.057; anal lump within last 6 months: p = 0.182).ConclusionsAmong MSM age 35 years and older, most anal symptoms are not a useful marker of anal HSIL.