Men Having Sex With Men Population Research Articles

Evaluation of the quality and reliability of anal cancer and its precancerous lesions-related content on YouTube: a cross-sectional study

ObjectivesThis research aims at evaluating the quality of anal cancer and its precancerous lesions-related videos on YouTube.DesignCross-sectional survey design.SettingUSA.ParticipantsThe top 150 videos on YouTube were selected for analysis based on...

Exploring access to HIV-related services and programmatic gaps for Men having Sex with Men (MSM) in rural India- a qualitative study.

Despite the Link Worker Scheme to address the HIV risk and vulnerabilities in rural areas, reaching out to unreached men having sex with men (MSM) remains a challenge in rural India. This study explored issues around health care access and programmatic gaps among MSM in rural settings of India. We conducted eight Focused Group Discussions (FGDs), 20 Key Informant Interviews (KIIs), and 20 In-Depth Interviews (IDIs) in four rural sites in Maharashtra, Odisha, Madhya Pradesh, and Uttar Pradesh between November 2018 and September 2019. The data in the local language were audio-recorded, transcribed, and translated. Data were analyzed in NVivo version 11.0 software using the grounded theory approach. Primary barriers to health care access were lack of knowledge, myths and misconceptions, not having faith in the quality of services, program invisibility in a rural setting, and anticipated stigma at government health facilities. Government-targeted intervention services did not seem to be optimally advertised in rural areas as MSM showed a lack of information about it. Those who knew reported not accessing the available government facilities due to lack of ambient services, fear of the stigma transforming into fear of breach of confidentiality. One MSM from Odisha expressed, "…they get fear to go to the hospital because they know that hospital will not maintain confidentiality because they are local people. If society will know about them, then family life will be disturbed" [OR-R-KI-04]. Participants expressed the desire for services similar to those provided by the Accredited Social Health Activists (ASHA), frontline health workers for MSM. Programme invisibility emerges as the most critical issue for rural and young MSM. Adolescent and panthis emerged as Hidden MSM and they need focused attention from the programme. The need for village-level workers such as ASHA specifically for the MSM population emerged. MSM-friendly health clinics would help to improve healthcare access in rural MSMs under Sexual and Reproductive Health Care.

Epidemiology of symptomatic infective anoproctitis in a population of men having sex with men (MSM).

Anoproctitis due to Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) are Sexual Transmitted Infections (STIs) reported in MSM population. This study describes clinical and microbiological epidemiology of infective anoproctitis in MSM population. All patients with symptomatic anoproctitis consulting at the proctology Institute of Saint-Joseph's Hospital, Paris, were included. Detection of CT/NG was performed by PCR GeneXpertR and other STIs pathogens Mycoplasma sp., HSV, CMV and T. pallidum were detected by multiplex PCR Allplex (mPCR). Symptoms most frequently reported were pain, rectal bleeding and purulent flow in 66%, 52% and 49% of cases, respectively. On the 311 rectal samples collected, 171 (55.2%) were positive to CT/NG. Among the 194 used for mPCR, 148 were positive to STIs pathogens (76.2%) including 106 samples (71.6%) positive in coinfections. Among NG infections, 22.6% of the strains were resistant to azithromycin and 26.8% to tetracyclines. Anorectal infections in this MSM population showed a high prevalence of not only CT/NG but also other pathogens involved in STIs. The high level of coinfections confirms the requirement of accurate PCR tests to improve diagnosis. This study describing increasing antibiotic resistances for NG strains confirms the updating of international guidelines on antibiotic treatments recommendations.

Testing as Prevention of Resistance in Bacteria Causing Sexually Transmitted Infections-A Population-Based Model for Germany.

Prescribed antibiotic treatments which do not match the therapeutic requirements of potentially co-existing undetected sexually transmitted infections (STIs) can facilitate the selection of antibiotic-drug-resistant clones. To reduce this risk, this modelling assessed the potential applicability of reliable rapid molecular test assays targeting bacterial STI prior to the prescription of antibiotic drugs. The modelling was based on the prevalence of three bacterial STIs in German heterosexual and men-having-sex-with-men (MSM) populations, as well as on reported test characteristics of respective assays. In the case of the application of rapid molecular STI assays for screening, the numbers needed to test in order to correctly identify any of the included bacterial STIs ranged from 103 to 104 for the heterosexual population and from 5 to 14 for the MSM population. The number needed to harm—defined as getting a false negative result for any of the STIs and a false positive signal for another one, potentially leading to an even more inappropriate adaptation of antibiotic therapy than without any STI screening—was at least 208,995 for the heterosexuals and 16,977 for the MSM. Therefore, the screening approach may indeed be suitable to avoid unnecessary selective pressure on bacterial causes of sexually transmitted infections.

Quantifying the reduction in sexual transmission of HIV-1 among MSM by early initiation of ART: A mathematical model.

BackgroundWe analyzed the effect of time to initiation of antiretroviral therapy (ART) after diagnosis on the probability of HIV-1 transmission events (HIV-TE) in naïve HIV-1-infected men having sex with men (MSM).SettingMathematical model.MethodsWe used discrete event simulation modeling to estimate the probability of HIV-TE in the first 8 weeks after ART initiation; we varied ART initiation from D0 to D28 after simulated “diagnosis”. The model inputs used sexual behavior parameters from the MSM population of the START trial, and transmission rates per-sex act and HIV-1 RNA from recent meta-analyses. HIV-1 RNA decay curves were modeled from the databases of Single (efavirenz [EFV] v dolutegravir [DTG]), Spring-2 (raltegravir [RAL] v DTG), and Flamingo (darunavir/ritonavir [DRVr] v DTG) trials.ResultsWe found that the number of HIV-TE per index patient in the first 8 weeks after ART initiation increased linearly for same-day ART to initiation on day 28. Small but statistically significant advantages of integrase strand transfer inhibitors (INSTI) over EFV and DRVr were found.ConclusionsRapid, if not same-day initiation of INSTI-based ART to newly diagnosed HIV-infected MSM has the potential for substantial public health benefits related to decreases in HIV-TE.

Immune profile at HIV infection diagnosis: Evolution in the French Alps area over the last 20 years

ObjectivesHealth of HIV-infected people relies on early antiretroviral therapy, i.e. early diagnosis. We aimed to determine whether the characteristics at HIV diagnosis in two French medical centres changed over the last 20 years. Patients and methodsAll individuals diagnosed with HIV infection in Grenoble University Hospital (N=814) and Annecy Hospital (N=246) between 1997 and 2015 were included. We collected age, country of birth, mode of transmission, CD4T cell count, CD4/CD8 ratio, and HIV viral load. ResultsAmong the 1060 patients (mean age 37.4±11 years, 70.2% of men), 42.5% were men having sex with men (MSM); 65.2% were born in France, and 24.4% were born in Africa. Mean CD4T cell count at diagnosis was 396±288/mm3 and was stable over the study period when considering all patients; when considering the MSM group, a significant increase over time was observed, with a mean increase of 7.3 CD4/mm3 per year (P<0.001). A higher CD4 count at diagnosis was observed after 2005 (400±289 vs 468±271/mm3, P=0.005). The proportion of MSM patients with a CD4 count<200/mm3 at diagnosis was lower after 2005 (14.7% after 2005 and 25.6% before, P=0.028) This was not observed in heterosexual patients (born in Africa or not). ConclusionIn the MSM population, CD4 count at diagnosis is higher after 2005, suggesting that screening campaigns have become more efficient. This was not observed in other populations, who should be better targeted in future strategies.

Evaluation of community-based HIV self-testing delivery strategies on reducing undiagnosed HIV infection, and improving linkage to prevention and treatment services, among men who have sex with men in Kenya: a programme science study protocol

BackgroundHIV prevalence among men having sex with men (MSM) in Kenya is 18.2%. Despite scale-up of HIV testing services, many MSM remain unaware of their HIV status and thus do not benefit from accessing HIV treatment or prevention services. HIV self-testing (HIVST) may help address this gap. However, evidence is limited on how, when, and in what contexts the delivery of HIVST to MSM could increase awareness of HIV status and lead to early linkage to HIV treatment and prevention.MethodsThe study will be embedded within existing MSM-focused community-based HIV prevention and treatment programmes in 3 counties in Kenya (Kisumu, Mombasa, Kiambu). The study is designed to assess three HIV testing outcomes among MSM, namely a) coverage b) frequency of testing and c) early uptake of testing. The study will adopt a mixed methods programme science approach to the implementation and evaluation of HIVST strategies via: (i) a baseline and endline bio-behavioural survey with 1400 MSM; (ii) a socio-sexual network study with 351 MSM; (iii) a longitudinal qualitative cohort study with 72 MSM; (iv) routine programme monitoring in three sites; (v) a programme-specific costing exercise; and (vi) mathematical modelling. This protocol evaluates the impact of community-based implementation of HIV self-testing delivery strategies among MSM in Kenya on reducing the undiagnosed MSM population, and time for linkage to prevention, treatment and care following HIV self-testing. Baseline data collection started in April 2019 and the endline data collection will start in July 2020.DiscussionThis study is one of the first programme science studies in Sub-Saharan Africa exploring the effectiveness of integrating HIVST interventions within already existing HIV prevention and treatment programmes for MSM in Kenya at scale. Findings from this study will inform national best approaches to scale up HIVST among MSM in Kenya.

Phylogenetic analysis of the Belgian HIV-1 epidemic reveals that local transmission is almost exclusively driven by men having sex with men despite presence of large African migrant communities

To improve insight in the drivers of local HIV-1 transmission in Belgium, phylogenetic, demographic, epidemiological and laboratory data from patients newly diagnosed between 2013 and 2015 were combined and analyzed. Characteristics of clustered patients, paired patients and patients on isolated branches in the phylogenetic tree were compared. The results revealed an overall high level of clustering despite the short time frame of sampling, with 47.6% of all patients having at least one close genetic counterpart and 36.6% belonging to a cluster of 3 or more individuals. Compared to patients on isolated branches, patients in clusters more frequently reported being infected in Belgium (95.1% vs. 47.6%; p < 0.001), were more frequently men having sex with men (MSM) (77.9% vs. 42.8%; p < 0.001), of Belgian origin (68.2% vs. 32.9%; p < 0.001), male gender (92.6% vs. 65.8%; p < 0.001), infected with subtype B or F (87.8% vs. 43.4%; p < 0.001) and diagnosed early after infection (55.4% vs. 29.0%; p < 0.001). Strikingly, Sub-Saharan Africans (SSA), overall representing 27.1% of the population were significantly less frequently found in clusters than on individual branches (6.0% vs. 41.8%; p < 0.001). Of the SSA that participated in clustered transmission, 66.7% were MSM and this contrasts sharply with the overall 12.0% of SSA reporting MSM. Transmission clusters with SSA were more frequently non-B clusters than transmission clusters without SSA (44.4% versus 18.2%). MSM-driven clusters with patients of mixed origin may account, at least in part, for the increasing spread of non-B subtypes to the native MSM population, a cross-over that has been particularly successful for subtype F and CRF02_AG.The main conclusions from this study are that clustered transmission in Belgium remains almost exclusively MSM-driven with very limited contribution of SSA. There were no indications for local ongoing clustered transmission of HIV-1 among SSA.

Genetic diversity and transmission networks of HIV-1 strains among men having sex with men (MSM) in Lomé, Togo

Understanding the HIV epidemic in key populations is important. Today only scarce information is available on HIV-1 strains that circulate in men having sex with men (MSM) in sub-Saharan Africa. Here, we studied for the first time the genetic diversity of HIV-1 strains circulating in the MSM population in Lomé, the capital city from Togo. The overall subtype/CRF distribution in pol (protease and/or partial reverse transcriptase (RT)) among the 79 HIV-1 strains from MSM was as follows: CRF02_AG (72%, n=57), subtype G (2.5%, n=2), sub-subtype A3 (1.3%, n=1), and unique recombinant forms (URF) (24%, n=19). Among the 19 URFs four different mosaic structures were observed, annotated as URF1 to URF4. Fifteen sequences (URF1) had the same mosaic structure in pol (G/CRF02_AG) and could represent a new circulating recombinant form (CRF). Phylogenetic analysis of the RT sequences showed that there were several introductions of CRF02_AG strains in the MSM population, however half of the CRF02_AG and all URF1 strains formed a separate, well-supported cluster suggesting one major introduction of CRF02_AG in the MSM population followed by efficient transmission and emergence of a possible new CRF. At least 40% of the strains fell into recent transmission chains involving two to seven MSM. Comparison with >950 HIV-1 sequences from previous studies in Togo showed intermixing of the HIV-1 epidemics between MSM and the general population. Moreover, an HIV-1 strain from a recently HIV-1 infected male patient from Germany, fell within a cluster of HIV-1 strains from MSM from Togo, illustrating recent exchange between MSM from Africa and people from other geographic regions. With growing evidence of the importance of MSM in the dynamic of the HIV epidemic in Africa there is an urgent need for appropriate interventions to limit HIV transmission in this population group.

La syphilis à Montpellier de 2002 à 2011. Enquête dans le service de dermatologie du CHRU et au CDAG-CIDDIST

In a context of resurgent syphilis in France since 2000, we conducted a retrospective study in two different centres in Montpellier, France: the dermatology department of a public hospital and an anonymous and free centre for provision of information, diagnosis and treatment of venereal diseases (CDAG-CIDDIST). All patients with syphilis seen from January 2002 to December 2011 were included with the collaboration of the National Health Institute (InVS) and the Bacteriology Department of the public hospital. Epidemiology, clinical presentation, serological data, and treatment and monitoring data for up to 2 years were recorded. One hundred and seventy-five cases of syphilis were diagnosed: 154 at the CDAG and 21 at the dermatology unit. Ninety-six percent of cases concerned men with a median age of 36 years. Eighty-two percent of these cases involved men having sex with men (MSM). Forty-nine percent of cases were diagnosed in the secondary stage, 22% in the primary stage and 28% in the latent stage. The treatment administered in the majority of cases (73%) was benzathine-penicillin G. The numbers of patients showing incomplete follow-up were equal at both centres, with 31 patients (17.7%) failing to attend the follow-up visit. A decrease of at least 2 dilutions in VDRL score occurred in the year following treatment for 93 of 103 patients (90%). Patients managed at the dermatology department were older than their counterparts managed at the CDAG and exhibited more frequent cutaneous eruptions (58% vs. 3%, P<0.0001) but were less frequently bisexual. However, no significant differences were seen concerning sex and associated infections (hepatitis, gonococcal infection, HPV or herpes). Syphilis is on the rise, especially in the MSM population. The epidemiological characteristics of our cohort were consistent with those of other Western European countries. Although the reasons for consultation differed between CDAG/CIDDIST and the dermatology department, the two centres are complementary. Benzathine-penicillin G was the most commonly used treatment, in accordance with the recommendations. Measures must be introduced to improve patient monitoring without compromising anonymity.

Comprehensive Characterization of the Transmitted/Founder env Genes From a Single MSM Cohort in China.

The men having sex with men (MSM) population has become one of the major risk groups for HIV-1 infection in China. However, the epidemiological patterns, function of the env genes, and autologous and heterologous neutralization activity in the same MSM population have not been systematically characterized. The env gene sequences were obtained by the single genome amplification. The time to the most recent common ancestor was estimated for each genotype using the Bayesian Markov Chain Monte Carlo approach. Coreceptor usage was determined in NP-2 cells. Neutralization was analyzed using Env pseudoviruses in TZM-bl cells. We have obtained 547 full-length env gene sequences by single genome amplification from 30 acute/early HIV-1--infected individuals in the Beijing MSM cohort. Three genotypes (subtype B, CRF01_AE, and CRF07_BC) were identified and 20% of the individuals were infected with multiple transmitted/founder (T/F) viruses. The tight clusters of the MSM sequences regardless of geographic origins indicated nearly exclusive transmission within the MSM population and limited number of introductions. The time to the most recent common ancestor for each genotype was 10-15 years after each was first introduced in China. Disparate preferences for coreceptor usages among 3 genotypes might lead to the changes in percentage of different genotypes in the MSM population over time. The genotype-matched and genotype-mismatched neutralization activity varied among the 3 genotypes. The identification of unique characteristics for transmission, coreceptor usage, neutralization profile, and epidemic patterns of HIV-1 is critical for the better understanding of transmission mechanisms, development of preventive strategies, and evaluation of vaccine efficacy in the MSM population in China.

Community-Based HIV-1 Early Diagnosis and Risk Behavior Analysis of Men Having Sex with Men in Hong Kong.

The increasing prevalence of HIV-1 among men having sex with men (MSM) calls for an investigation of HIV-1 prevalence and incidence in MSM by early diagnosis to assist with early preventive interventions in Hong Kong. The participants were recruited randomly from MSM communities within a one-year period. Rapid HIV Test (RHT) and real-time dried blood spot (DBS)-based quantitative polymerase chain reaction (DBS-qPCR) were used for the early diagnosis of 474 participants. Risk behavior analysis was performed by studying information obtained from the participants during the study period. The HIV-1 prevalence and incident rates in the studied MSM population were 4.01% (19/474) and 1.47% (7/474), respectively. Three infected participants were found at the acute phase of infection by DBS-qPCR. Only 46.4% (220/474) MSM were using condoms regularly for anal sex. HIV infection significantly correlated with unprotected receptive anal sex and syphilis infection. An increased number of infections was found among foreign MSM in Hong Kong. This study is the first to use DBS-qPCR to identify acutely infected individuals in a community setting and to provide both the prevalence and incident rates of HIV-1 infection among MSM in Hong Kong. The risk analysis provided evidence that behavior intervention strengthening is necessary to fight against the increasing HIV-1 epidemic among MSM in Hong Kong and surrounding regions in Asia.

HIV-1 subtype diversity and transmission clusters among men having sex with men who recently got HIV-l infection, in Zhejiang province

To understand the HIV-1 subtype diversity and transmission characteristics in men having sex with men (MSM) in Zhejiang province. A total of 233 newly diagnosed as HIV-1 positive patients in 2011 were screened out by BED capture enzyme immunoassay (BED-CEIA). Among them, 107 eligible subjects were enrolled for further molecular epidemiological study. Viral RNA was extracted from plasma samples and followed by reverse transcription PCR and nested PCR for amplification of pol gene fragments, sequencing, and bioinformatics analysis. There were no statistically significant differences regarding the social demographic distribution between the subjects under study and those recently infected MSM population. The rate of success for sequence acquisition was 94.4% (101/107). The highest proportion of subtype was CRF01_AE (62.4%), followed by CRF07_BC (31.7%) and with three cases of subtype B, one case of CRF55_01B and two cases of unique recombinant form (CRF01_AE/B and CRF01_AE/CRF07_BC). The phylogenetic trees were mainly divided into CRF01_AE cluster 1, cluster 2 and CRF07_BC cluster 3. The strains located in Hangzhou were diffused in the branches of phylogenetic tree. 10 transmission clusters were found, in which 80% involved two or more regions and 90% was associated with patients residing in Hangzhou. Three surveillance drug resistance mutations (M46I, T215S and G190A) were found in three samples (each sample harbored only one resistance mutation). The overall rate of transmitted drug resistance (TDR) was 2.97%. The increasing complexity of HIV was noticed in MSM in Zhejiang province. However, the prevalence of TDR was low. Cross-regional HIV transmission in MSM was common, which inferred from the study. Hangzhou might play a central regional role in the intra-provincial spread of HIV, to form an interwoven complex network in the MSM population.

Molecular epidemiology related to human immunodeficiency virus type 1 infection in men having sex with men in Xi'an

To investigate the subtype distribution of HIV-1 infection among men having sex with men (MSM) in Xi'an city. 5 ml anti-coagulating blood samples were collected from MSM who had been reported during 2010-2012 in Xi'an. Both gag and env genes were amplified by nested RT-PCR from the extracted RNA and then sequenced. The acquired sequences were compared with international subtype references, and then the genetic distances were calculated and phylogenetic trees were constructed by Mega 5.2. Epidemiological information including sexual behavior characteristics, history of drug use, blood donation, etc. were gathered. 168 samples were successfully amplified and sequenced. Results from Phylogenic analysis showed that the gag and env sequences of 165 samples shared the same subtypes, of which 79 (47.0%) were CRF01_AE, 74 (44.0%) were CRF07_BC and 12 (7.1%) belonged to subtype B. There were 3 samples with gag and env sequences classified into different subtypes, of which 2(1.2%) were CRF01_AE/A1, and the other 1 was CRF07_BC/CRF01_AE. At least three HIV-1 subtypes including CRF01_AE, CRF07_BC were identified among MSM population in Xi'an city.

High frequency of HIV-1 infections with multiple HIV-1 strains in men having sex with men (MSM) in Senegal

Circulating and unique recombinant HIV-1 strains continue to be identified and their number increases over time, suggesting that co-infection with multiple HIV-1 is frequent. In this study we analyzed to what extent dual infections with different HIV-1 variants occur in a population group with high risk behaviour, high HIV-1 prevalence and in an area where multiple HIV-1 subtypes and Circulating Recombinant Forms (CRFs) co-circulate. We studied 69 MSM with our recently developed multi-region hybridization assay (MHA), based on fluorescent probe detection for eight common variants circulating in West and West Central Africa. At least 11 (15.9%) of the 69 patients were simultaneously infected with two different HIV-1 subtypes and/or CRFs. Among the 29 samples identified as subtype C by MHA in gag, 15 (57.7%) reacted with both C1 and C2 probes. Sequence analysis suggests that the majority of the samples reactive with C1 and C2 probes are most likely infected with two different subtype C clades. Single genome amplification and DNA dilutions confirmed dual infection with subtype D and C for MSM1193, triple infection with two different C subtype strains and one CRF02_AG strain in MSM1157 and showed that MSM3017 is at least co-infected with CRF06_cpx and CRF02_AG and another strain that could not be classified. Comparison of all subtype C sequences from the MSM population and from the general population from this and previous studies confirmed the intermixing of HIV-1 variants between low-risk women and high-risk men as shown by the intermixing of subtype C variants from MSM1157 and a female patient (02SN-HALD478). Comparison of dual infection rates between the general population and MSM in Senegal, show also clearly the importance of high HIV prevalence and high risk behavior in dual infections and subsequent intermixing of HIV-1 variants which can lead to emergence and spread of new recombinants (CRFs).

P6.036 Stigma & Discrimination Among HIV-Infected MSM Population in the Sub-Saharan Africa

People Living with HIV/AIDS (PLWHA) in Sub-Saharan Africa face stigma and discrimination including significant health challenges. Social, religious and cultural contexts most often contribute to various forms of stigma and...

Community-Based Surveys for Determining the Prevalence of HIV, Chlamydia, and Gonorrhoea in Men Having Sex with Men in Hong Kong.

Background. Community sampling of men having sex with men (MSM) for human immunodeficiency virus (HIV) and sexually transmitted infections prevalence studies poses challenges in view of problems in logistics and the hidden nature of MSM population. Methods. MSM in Hong Kong were recruited through social venues and the Internet. All participants were invited to complete a behavioural questionnaire and submit a urine specimen for HIV, Chlamydia, and gonorrhoea testing. Results. Totally, 994 MSM were recruited. No differences between venue and online-recruited respondents were identified regarding their demographics and infection status. The prevalence of HIV, Chlamydia, and gonorrhoea was 3.6% (95% CI: 2.6–5.0%), 4.7% (95% CI: 3.6–6.2%), and 0.2% (95% CI: 0.1–0.7%), respectively. Of all HIV cases, only 8.3% were aware of the infection; reflecting newly infected MSM were probably overrepresented. Some 58.3% had had HIV test within the past year, and 11.1% had CT/NG coinfection. HIV infection was associated with group sex [aOR: 2.67 (1.03–6.92)], receiving money for anal sex [aOR: 4.63 (1.12–19.18)], and unprotected anal sex with nonregular partners [aOR: 3.047 (1.16–8.01)]. Conclusion. Difference between venue- and online-recruited MSM was observed. A combination of sampling methods is complementary for epidemiology purpose. Overall, risk behaviours practised by undiagnosed HIV-positive MSM remains a cause for concern.

Risk of HIV or second syphilis infection in Danish men with newly acquired syphilis in the period 2000–2010

ObjectivesRisk of subsequent diagnosis of HIV in persons diagnosed with newly acquired syphilis, and syphilis in HIV-infected persons, are of interest as these infections are markers of unsafe sex.MethodsFrom a...

P102 A highly cost-effective and targeted service promotion campaign using the social media site Facebook

BackgroundFacebook is the leading social media site in the world with over 30 million active users in the UK, 50% of who log on every day. It enables promotion to...

The Origin and Evolutionary History of HIV-1 Subtype C in Senegal

BackgroundThe classification of HIV-1 strains in subtypes and Circulating Recombinant Forms (CRFs) has helped in tracking the course of the HIV pandemic. In Senegal, which is located at the tip of West Africa, CRF02_AG predominates in the general population and Female Sex Workers (FSWs). In contrast, 40% of Men having Sex with Men (MSM) in Senegal are infected with subtype C. In this study we analyzed the geographical origins and introduction dates of HIV-1 C in Senegal in order to better understand the evolutionary history of this subtype, which predominates today in the MSM populationMethodology/Principal FindingsWe used a combination of phylogenetic analyses and a Bayesian coalescent-based approach, to study the phylogenetic relationships in pol of 56 subtype C isolates from Senegal with 3,025 subtype C strains that were sampled worldwide. Our analysis shows a significantly well supported cluster which contains all subtype C strains that circulate among MSM in Senegal. The MSM cluster and other strains from Senegal are widely dispersed among the different subclusters of African HIV-1 C strains, suggesting multiple introductions of subtype C in Senegal from many different southern and east African countries. More detailed analyses show that HIV-1 C strains from MSM are more closely related to those from southern Africa. The estimated date of the MRCA of subtype C in the MSM population in Senegal is estimated to be in the early 80's.Conclusions/SignificanceOur evolutionary reconstructions suggest that multiple subtype C viruses with a common ancestor originating in the early 1970s entered Senegal. There was only one efficient spread in the MSM population, which most likely resulted from a single introduction, underlining the importance of high-risk behavior in spread of viruses.