SARS-CoV-2-Specific IgG and IgA response in maternal blood and breastmilk of vaccinated naïve and convalescent lactating participants.

Background: Recent studies have shown the presence of SARS-CoV-2-specific antibodies in the milk of breastfeeding mothers vaccinated with mRNA and convalescent. However, limited information is available in lactating women receiving other vaccine platforms used in developing countries, such as the inactivated SARS-CoV-2 vaccine BBIBP-CorV (Sinopharm) and the non-replicating adenovirus vaccines Sputnik V (Gamaleya Institute) and ChAdOx1-S (Oxford AstraZeneca). Methods: Here, we evaluated anti-SARS-CoV-2 IgG and IgA levels in both serum and milk samples using a longitudinal and a cross-sectional cohort of 208 breastfeeding vaccinated women from Argentina with or without previous SARS-CoV-2 infection. Results: The analysis showed that IgA levels remain constant in serum and milk of breastfeeding mothers between the first and second doses of vector-based vaccines (Sputnik V and ChAdOx1-S). After the second dose, anti-spike IgA was found positive in 100% of the serum samples and in 66% of breastmilk samples. In addition, no significant differences in milk IgA levels were observed in participants receiving BBIBP-CorV, Sputnik V or ChAdOx1-S. IgG levels in milk increased after the second dose of vector-based vaccines. Paired longitudinal samples taken at 45 and 120 days after the second dose showed a decrease in milk IgG levels over time. Study of IgA levels in serum and milk of vaccinated naïve of infection and vaccinated-convalescent breastfeeding participants showed significantly higher levels in vaccinated-convalescent than in participants without previous infection. Conclusion: This study is relevant to understand the protection against SARS-CoV-2 by passive immunity in newborns and children who are not yet eligible to receive vaccination.

Multilocus sequence typing of Treponema pallidum pallidum in children with acquired syphilis by nonsexual contact.

Background: There are scarce data of Treponema pallidum subsp. pallidum (TPA) characterization in children with syphilis. Nonsexually acquired transmission (NSAT) of TPA is possible in infants through close contact. Methods: A descriptive study in five families with NSAT of syphilis was conducted. Polymerase chain reaction detection of TPA in pediatric index cases (n = 6) and their relatives (n = 44) were conducted followed by multilocus sequence typing (MLST). Results: TPA was detected in swab samples in 16 cases and 12 were characterized by MLST. Nichols lineage was identified in two of five families and SS14-lineage in three of five. In four families, MLST profiles linked index cases to relatives. Conclusion: This is the first report of TPA characterization in children infected by NSAT.

Syphilis is a disease caused by the bacterium Treponema pallidum subsp. pallidum (TPA). Although it is considered a sexually transmitted disease, syphilis can also be transmitted by nonsexual close contact with active lesions. There are clinical reports of this route of transmissions in children; however, there are no molecular characterizations of TPA in this population. A multidisciplinary study (epidemiological, clinical, social and molecular) was performed in six children from five families with clinical diagnosis of nonsexually transmitted syphilis. As a result, 18 infected persons were detected. In 16 individuals the presence of the bacterium genetic material was confirmed by molecular biology techniques, and in 12, its strain was analyzed. When we compared the data, we observed that in four families, the child's strain coincided with the one found in close contact, while in one family, this could not be determined. To our knowledge, this is the first report of TPA characterization in children, which underscore the importance of including molecular biology techniques in complex clinical scenarios such as these.

High frequency of Nichols-like strains and increased levels of macrolide resistance in Treponema pallidum in clinical samples from Buenos Aires, Argentina.

Globally, 94% of Treponema pallidum subsp. pallidum (TPA) clinical strains belong to the SS14-like group and 6% to the Nichols-like group, with a prevalence of macrolide resistance of 90%. Our goal was to determine whether local TPA strain distribution and macrolide resistance frequency have changed significantly since our last report, which revealed that Buenos Aires had a high frequency of Nichols-like strains (27%) and low levels of macrolide resistance (14%). Swab samples from patients with suspected syphilis were collected during 2015-2019 and loci TP0136, TP0548, TP0705 were sequenced in order to perform multilocus sequence typing. Strains were classified as Nichols-like or SS14-like. The presence of macrolide resistance-associated mutations was determined by examination of the 23S rDNA gene sequence. Of 46 typeable samples, 37% were classified as Nichols-like and 63% as SS14-like. Macrolide resistance prevalence was 45.7%. Seven allelic profiles were found, five were SS14-like and two were Nichols-like. The frequency of Nichols-like strains increased between studies (26.8% vs. 37%, p = 0.36). A dramatic increase was found in the frequency of macrolide resistant strains between studies (14.3% vs. 45.7%, p = 0.005). Our results are in agreement with international trends and underscore the need to pursue further TPA molecular typing studies in South America.

Evaluación de intervenciones durante la pandemia COVID-19: desarrollo de un modelo basado en subpoblaciones con distintas tasas de contacto / Evaluation of interventions during the COVID-19 pandemic: development of a modelbased on subpopulations with different contact rates

Resumen Si bien se han realizado múltiples intentos de modelar matemáticamente la pande-mia de la enfermedad por coronavirus 2019 (COVID-19), causada por SARS-CoV-2, pocos modeloshan sido pensados como herramientas interactivas accesibles para usuarios de distintos ámbitos.El objetivo de este trabajo fue desarrollar un modelo que tuviera en cuenta la heterogeneidadde las tasas de contacto de la población e implementarlo en una aplicación accesible, que per-mitiera estimar el impacto de posibles intervenciones a partir de información disponible. Sedesarrolló una versión ampliada del modelo susceptible-expuesto-infectado-resistente (SEIR),denominada SEIR-HL, que asume una población dividida en dos subpoblaciones, con tasas decontacto diferentes. Asimismo, se desarrolló una fórmula para calcular el número básico dereproducción (R0) para una población dividida en n subpoblaciones, discriminando las tasas decontacto de cada subpoblación según el tipo o contexto de contacto. Se compararon las pre-dicciones del SEIR-HL con las del SEIR y se demostró que la heterogeneidad en las tasas decontacto puede afectar drásticamente la dinámica de las simulaciones, aun partiendo de lasmismas condiciones iniciales y los mismos parámetros. Se empleó el SEIR-HL para mostrar elefecto sobre la evolución de la pandemia del desplazamiento de individuos desde posiciones dealto contacto hacia posiciones de bajo contacto. Finalmente, a modo de ejemplo, se aplicó elSEIR-HL al análisis de la pandemia de COVID-19 en Argentina; también se desarrolló un ejemplode uso de la fórmula del R0. Tanto el SEIR-HL como una calculadora del R0fueron implementadosinformáticamente y puestos a disposición de la comunidad.

Abstract Although multiple attempts have been made to mathematically model the currentepidemic of SARS-CoV-2, the causative agent of coronavirus disease 2019 (COVID-19), fewmodels have been conceived as accessible interactive tools for users from various backgrounds.The goal of this study was to develop a model that took into account the heterogeneity incontact rates within the population and to implement it in an accessible application allowingto estimate the impact of possible interventions based on available information. An extendedversion of the Susceptible-Exposed-Infected-Resistant (SEIR) model, named SEIR-HL, was deve-loped, assuming a population divided into two subpopulations, with different contact rates.Additionally, a formula for the calculation of the basic reproduction number (R0) for a popula-tion divided into n subpopulations was proposed, where the contact rates for each subpopulationcan be distinguished according to contact type or context. The predictions made by SEIR-HLwere compared to those of SEIR, showing that the heterogeneity in contact rates can drama-tically affect the dynamics of simulations, even when run from the same initial conditions andwith the same parameters. SEIR-HL was used to predict the effect on the epidemic evolution ofthe displacement of individuals from high-contact positions to low-contact positions. Lastly, byway of example, SEIR-HL was applied to the analysis of the SARS-CoV-2 epidemic in Argentinaand an example of the application of the R0formula was also developed. Both the SEIR-HLmodel and an R0calculator were computerized and made available to the community.

[Evaluation of interventions during the COVID-19 pandemic: development of a model based on subpopulations with different contact rates]. / Evaluación de intervenciones durante la pandemia COVID-19: desarrollo de un modelo basado en subpoblaciones con distintas tasas de contacto.

Although multiple attempts have been made to mathematically model the current epidemic of SARS-CoV-2, the causative agent of coronavirus disease 2019 (COVID-19), few models have been conceived as accessible interactive tools for users from various backgrounds. The goal of this study was to develop a model that took into account the heterogeneity in contact rates within the population and to implement it in an accessible application allowing to estimate the impact of possible interventions based on available information. An extended version of the Susceptible-Exposed-Infected-Resistant (SEIR) model, named SEIR-HL, was developed, assuming a population divided into two subpopulations, with different contact rates. Additionally, a formula for the calculation of the basic reproduction number (R0) for a population divided into n subpopulations was proposed, where the contact rates for each subpopulation can be distinguished according to contact type or context. The predictions made by SEIR-HL were compared to those of SEIR, showing that the heterogeneity in contact rates can dramatically affect the dynamics of simulations, even when run from the same initial conditions and with the same parameters. SEIR-HL was used to predict the effect on the epidemic evolution of the displacement of individuals from high-contact positions to low-contact positions. Lastly, by way of example, SEIR-HL was applied to the analysis of the SARS-CoV-2 epidemic in Argentina and an example of the application of the R0 formula was also developed. Both the SEIR-HL model and an R0 calculator were computerized and made available to the community.

Viral hepatitis and Treponema pallidum prevalence in persons who underwent premarital blood tests in Argentina.

The objective of this study was to estimate the prevalence of different serological markers of hepatitis A, B and C viruses and Treponema pallidum among the adult population of Argentina. To achieve this, adults who attended health services for premarital exams (which are mandatory and includes screening for syphilis) were recruited. A cross-sectional study was designed with a cluster sampling strategy. Couples who attended selected health services for premarital screening between 2013 and 2014 in Buenos Aires, Cordoba, Mendoza and Santa Fe provinces were included. A total of 3833 individuals were recruited. Anti-HAV prevalence was 63.9%, anti-HCV 0.3%, anti-HBc (without HBsAg) 1.9%, HBsAg 0.3%, and T pallidum 0.8%. Anti-HAV was higher among older participants, foreigners and those from the lower strata. HBV increased with age and was higher among foreigners and those with lower formal educational level. Anti-HCV frequency increased with age. Premarital screening of viral hepatitis could constitute an instance of diagnosis, vaccination and inclusion in care of those in need. Results from this study will allow the national hepatitis programs to design public policies in order to diminish the impact of these infections on the population.

Evaluation of the utility of a rapid test for syphilis at a sexually transmitted disease clinic in Buenos Aires, Argentina.

Even though syphilis can be easily diagnosed by simple and low-cost laboratory methods, it continues to be an important health problem. Rapid tests (RT) for the detection of treponemal antibodies can facilitate earlier diagnosis, access to treatment and linkage to care. The aim of this study was to analyse the usefulness of the incorporation of a RT in the detection of patients infected with T. pallidum in a sexually-transmitted disease (STD) clinic. Between March and December 2015, a syphilis RT was offered to patients who spontaneously attended the clinic. Conventional serology testing was additionally indicated to every participant. The RT for syphilis was offered to 1887 patients, of whom 31.1% agreed to get tested. VDRL test was performed in 84.0% of patients that were also tested with syphilis RT, with a significantly higher frequency observed among participants with reactive RT (94.3% vs. 79.8%, p < 0.001). These results showed that 33.7% of the participants were reactive for the RT and 27.0% were reactive for the VDRL test. Both tests were reactive in 24.9% and non-reactive in 64.3%. A high prevalence of active syphilis was detected in patients attending the clinic. The use of a syphilis RT had a positive impact, which in combination with the VDRL test increased the number of patients that were effectively diagnosed.

High Substance Use and HIV Risk Behavior Among Young Argentine Men Who Have Sex with Men.

In the United States young men who have sex with men have higher rates of substance use, higher HIV incidence, and less frequent HIV testing than their heterosexual counterparts and older MSM. Less is known about comparable populations in Latin America. As part of an epidemiological study, MSM were recruited through Respondent Driven Sampling in the metropolitan area of Buenos Aires, Argentina and answered a computerized behavioral survey. From the total of 500 MSM enrolled, a sub-sample of 233 aged 18-25 was analyzed. The sample was concentrated among lower socioeconomic strata, and only 16% identified as gay. Nearly half reported male, female, and transvestite sexual partners. Reported substance use was widespread ranging from 61% for marijuana to 20% for pasta base (cocaine sulfate). Seventy percent of the sample had never been tested for HIV infection; 3% tested positive for HIV and 8% for syphilis during the study.

Genomic characterization and molecular evolution analysis of subtype B and BF recombinant HIV-1 strains among Argentinean men who have sex with men reveal a complex scenario.

Currently, data on HIV-1 circulating strains among men who have sex with men (MSM) in Argentina is scarce. In South America, the distribution and the prevalence of BF recombinants are dissimilar and exhibit an underappreciated heterogeneity of recombinant structures. Here, we studied for the first time the genetic diversity of HIV-1 BF recombinants and their evolution over time through in-depth phylogenetic analysis and multiple recombination detection methods involving 337 HIV-1 nucleotide sequences (25 near full-length (NFL) and 312 partial pol gene) obtained from Argentinean MSM. The recombination profiles were studied using multiple in silico tools to characterize the genetic mosaicism, and phylogenetic approaches to infer their relationships. The evolutionary history of BF recombinants and subtype B sequences was reconstructed by a Bayesian coalescent-based method. By phylogenetic inference, 81/312 pol sequences clustered within BF clade. Of them, 46 sequences showed a genetic mosaic with CRF12_BF-like patterns, including plausible second-generation recombinants. Other CRFs_BF like (CRF17, 28, 29, 39, 42, 44, 47) and probable URFs_BF were less frequently found. Phylogenetic and recombination analyses on NFL sequences allowed a meticulous definition of new BF mosaics of genomic patterns. The Bayesian analyses pointed out quite consistent onset dates for the CRFs_BF clade based on B and F gene datasets (~1986 and ~1991 respectively). These results indicate that the CRFs_BF variants have been circulating among Argentinean MSM for about 30 years. This study reveals, through growing evidence showing the importance of MSM in the dynamics of the HIV-1 epidemic in Argentina, the coexistence of CRF12_BF-like and high diversity of strains exhibiting several BF mosaic patterns, including non-reported URFs that may reflect active clusters as potential intervention targets to hinder HIV-1 transmission.

High acceptability of rapid HIV self-testing among a diverse sample of MSM from Buenos Aires, Argentina.

INTRODUCTION: The objective of this study was to explore the acceptability of rapid HIV self-testing (RHST) among men who have sex with men (MSM). METHODS: During 2006-2009, a sample of 500 MSM was recruited through Respondent Driven Sampling for an HIV prevalence/incidence study. Attitude toward RHST was explored among HIV negative MSM. Data were weighted prior to analyses. RESULTS: Participants reported they were likely to buy RHST (74%), test themselves more frequently than they currently do (77%), and that the procedure would simplify testing (70%). Furthermore, 71% reported they would probably use it alone, 66% would use it with a steady partner, and 56% with a friend/partner. While a majority acknowledged that RHST use would deprive them of receiving counseling (61%), 74% declared they would go for help if they tested positive; 57% would use an RHST in order to avoid condoms. Probability of use surpassed 70% among gay and non-gay identified MSM as well as those with and without a previous HIV test. Those likely to buy RHST were older (p = 0.025) and more likely to identify as gay (p = 0.036). A total of 17% said they would think about killing themselves and 9% would attempt suicide if they tested positive. These MSM were more likely to be younger (p<0.001), with lower mood level (p<0.001) and greater feelings of loneliness (p = 0.026). CONCLUSIONS: The high acceptability of RHST found among MSM should encourage the authorities to consider the possibility of offering it for self-testing, as it can improve early diagnosis and prevention of future transmissions. However, further research is needed to understand how to best disseminate RHST among MSM who wish to use it and to offer support and linkage to care for those who test HIV-positive.

High Frequency of Illegal Drug Use Influences Condom Use Among Female Transgender Sex Workers in Argentina: Impact on HIV and Syphilis Infections.

The high prevalence of HIV and syphilis found among female transgender sex workers (FTSWs) in Argentina calls for the study of factors leading to negative health consequences. Given the particular characteristics observed in this population (high marginalization, school dropout, and low adherence to healthcare services), we explored the association of several socio-demographic characteristics with syphilis and HIV infections, and the determinants of condom use. This study revealed that FTSWs from Argentina were exposed to several risk factors decreasing thus their ability to negotiate condom use and leading to increased risk for transmission of HIV and other sexually transmitted infections (STIs). Strategies to reduce HIV and syphilis in this population should consider interventions aimed at decreasing violence and substance use which appear to be the most important determinants. Results of this study will contribute to the global information among FTSWs.

Molecular typing of Treponema pallidum isolates from Buenos Aires, Argentina: Frequent Nichols-like isolates and low levels of macrolide resistance.

A total of 54 clinical samples, including genital lesion swabs, whole blood and cerebrospinal fluid from patients diagnosed with syphilis were collected in 2006 and in 2013 in Buenos Aires, Argentina. Treponemal DNA was detected in 43 of the analyzed samples (79.6%) and further analyzed using Sequencing-based molecular typing (SBMT) and Enhanced CDC-typing (ECDCT). By SBMT, 10 different Treponema pallidum subsp. pallidum (TPA) genotypes were found, of which six were related to the TPA SS14 strain, and four to the TPA Nichols strain. The 23S rRNA gene was amplified in samples isolated from 42 patients, and in six of them (14.3%), either the A2058G (four patients, 9.5%) or the A2059G (two patients, 4.8%) mutations were found. In addition to Taiwan, Madagascar and Peru, Argentina is another country where the prevalence of Nichols-like isolates (26.8%) is greater than 10%.

Origin of modern syphilis and emergence of a pandemic Treponema pallidum cluster.

The abrupt onslaught of the syphilis pandemic that started in the late fifteenth century established this devastating infectious disease as one of the most feared in human history1. Surprisingly, despite the availability of effective antibiotic treatment since the mid-twentieth century, this bacterial infection, which is caused by Treponema pallidum subsp. pallidum (TPA), has been re-emerging globally in the last few decades with an estimated 10.6 million cases in 2008 (ref. 2). Although resistance to penicillin has not yet been identified, an increasing number of strains fail to respond to the second-line antibiotic azithromycin3. Little is known about the genetic patterns in current infections or the evolutionary origins of the disease due to the low quantities of treponemal DNA in clinical samples and difficulties in cultivating the pathogen4. Here, we used DNA capture and whole-genome sequencing to successfully interrogate genome-wide variation from syphilis patient specimens, combined with laboratory samples of TPA and two other subspecies. Phylogenetic comparisons based on the sequenced genomes indicate that the TPA strains examined share a common ancestor after the fifteenth century, within the early modern era. Moreover, most contemporary strains are azithromycin-resistant and are members of a globally dominant cluster, named here as SS14-Ω. The cluster diversified from a common ancestor in the mid-twentieth century subsequent to the discovery of antibiotics. Its recent phylogenetic divergence and global presence point to the emergence of a pandemic strain cluster.

Reseña del estudio "LINKS": Factores asociados a la infección por VIH en hombres que tienen sexo con hombres de Buenos Aires, Argentina / Review of the "LINKS" study: Factors associated with HIV infection in men who have sex with men in Buenos Aires, Argentina

Este artículo resume resultados publicados del proyecto LINKS. Un to-tal de 500 hombres que tienen sexo con hombres se incluyeron en un estudio de factores asociados a la infección por VIH, utilizando la meto-dología de Muestreo Dirigido por los Participantes (Respondent Driven Sampling, RDS, en inglés). El 24,5 % se identificó como homosexual, 36,2 % como bisexual, 21,9 % como heterosexual y 17,4 % como "otro". El 33 % de los participantes reportó haber tenido relaciones sexuales con hombres, mujeres y mujeres trans durante los 2 meses previos. La prevalencia de VIH, hepatitis B y sífilis fue de 17,3 %, 22,9 % y 20,5 %, respectivamente. Los participantes que sólo reportaron parejas sexua-les masculinas tuvieron prevalencias significativamente mayores. Más de dos tercios reportaron coito anal o vaginal sin protección durante los últimos dos meses. El 52 % nunca se había realizado el diagnóstico de VIH. El 25 % informó consumo ex-cesivo de alcohol y 34 % poli-consumo de drogas du-rante los dos meses previos. El 18 % de participantes reportó una experiencia sexual antes de los 13 años con una pareja al menos cuatro años mayor de edad. La aceptabilidad de los microbicidas y de la prueba casera del VIH fue alta

[Summary of the LINKS Study: Factors associated with HIV infection among men who have sex with men in Buenos Aires, Argentina]. / Reseña del estudio "LINKS": Factores asociados a la infección por VIH en hombres que tienen sexo con hombres de Buenos Aires, Argentina.

This article summarizes published findings from Project LINKS. A total of 500 men who have sex with men were recruited through Respondent Driven Sampling into this study on factors associated with HIV infection. Among participants, 24.5 % identified as gay, 36.2 % as bisexual, 21.9 % as heterosexual, and 17.4 % as "other"; 33 % reported having sex with men, women, and transgender women during the prior two months. Prevalence of HIV, Hepatitis B, and syphilis was 17.3 %, 22.9 %, and 20.5 %, respectively; rates were significantly higher among participants who only had male sex partners. Over two-thirds of participants reported unprotected anal or vaginal intercourse during the prior two months, and 52 %had never been tested for HIV. Twenty-five percent reported heavy drinking, and 34 % reported poly-drug use during the past two months. Eighteen percent of participants reported a sexual experience prior to the age of thirteen with a partner who was at least four years older. Acceptability of microbicides and HIV home testing was high.

Childhood sexual experiences with an older partner among men who have sex with men in Buenos Aires, Argentina.

This study sought to describe childhood sexual experiences with older partners (CSEOP) among men who have sex with men (MSM) in Buenos Aires, Argentina. MSM were recruited through respondent driven sampling. They responded to a computer administered self-interview with questions on CSEOP, operationalized as manual, oral, genital, or anal contact prior to age 13 with a partner at least 4 years older. Of the 500 respondents, only 25% identified as gay. Eighteen percent of the respondents reported CSEOP, the majority of whom did not feel they were hurt by the experience and did not consider it to be childhood sexual abuse (CSA). Over two-thirds of MSM who reported CSEOP said that their older partner was a female. Only 4% of those with a female partner felt their experience was CSA compared to 44% of those who had a male partner. Among all men reporting CSEOP, those who felt sexually abused were more likely to have been physically forced or threatened, physically hurt, and emotionally hurt than those who did not feel sexually abused. Having CSEOP, being hurt by the experiences, and perceiving the experiences as sexual abuse were not associated with current HIV sexual risk or substance use behavior. In this sample of MSM in Argentina, a substantial minority reported CSEOP. Those who felt they had been sexually abused were much more likely to have had an older male partner than an older female partner, and were more likely to report having been physically forced and threatened by their older partner.

HIV testing practices among men who have sex with men in Buenos Aires, Argentina.

The objective of the study was to explore HIV-testing practices among men who have sex with men (MSM) in Buenos Aires, Argentina, in light of current international health guidelines that recommend frequent HIV testing for MSM who engage in high-risk behavior. Participants, who were recruited using respondent-driven sampling (RDS), were 500 mostly young, nongay-identified MSM of low socioeconomic status, high levels of unemployment, living mainly in the less-affluent areas surrounding Buenos Aires, and lacking health insurance. They provided blood samples for HIV testing and responded to a Computer Assisted Self Interview. Fifty-two percent had never been tested for HIV, and 20% had been tested only once; 17% were found to be HIV infected, of whom almost half were unaware of their status. Main reasons for never having tested previously were: not feeling at risk, fear of finding out results, and not knowing where to get tested. Among those previously tested, men had been tested a median of 2 times with their most recent test having occurred a median of 2.7 years prior to study enrollment. Of those who had not tested positive before entering the study, only 41% returned for their results. HIV testing was infrequent and insufficient for early detection of infection, entry into treatment, and protection of sexual partners. This was particularly the case among nongay-identified MSM. Testing campaigns should aim to help MSM become aware of their risk behavior, decrease fear of testing by explaining available treatment resources and decreasing the stigma associated with HIV, and by publicizing information about free and confidential testing locations. Rapid HIV testing should be made available to eliminate the need for a return visit and make results immediately available to individuals who are tested.

HIV status disclosure among infected men who have sex with men (MSM) in Buenos Aires, Argentina.

Five hundred men who have sex with men were recruited in Buenos Aires using respondent driven sampling. Of them, 46 respondents (24 of them not gay identified) who were HIV infected were asked questions on serodisclosure. The sample was characterized by indicators of low socioeconomic status. Most of the respondents reported being in good to excellent health despite 42% of them having been diagnosed with AIDS. Only 10% of respondents had not disclosed their serostatus to at least one person. Coworkers and lovers or main sexual partners were those most likely to know the respondents' serostatus. Reactions to disclosure were for the most part supportive. Those who had not disclosed anticipated less favorable reactions than those who had disclosed. No significant differences were observed between gay and non-gay identified respondents. The progressive social environment of Argentina that includes federal laws recognizing gay marriage may contribute to create a climate favorable for serostatus disclosure.

Low frequency of male circumcision and unwillingness to be circumcised among MSM in Buenos Aires, Argentina: association with sexually transmitted infections.

OBJECTIVE: The aims of this study were to investigate the frequency of male circumcision among men who have sex with men (MSM) in Buenos Aires, Argentina; the association between circumcision and sexually transmitted infections (STIs); and, among those uncircumcised, the willingness to be circumcised. METHODS: A cross-sectional study was conducted among 500 MSM recruited through the respondent-driven sampling (RDS) technique. Participants underwent a consent process, responded to a Web-based survey that included questions on demographic information, sexual behaviour, and circumcision and provided biological samples. HIV, hepatitis B virus (HBV), hepatitis C virus (CV), Treponema pallidum, and human papiloma virus (HPV) diagnoses were performed using standard methodologies. For all analyses, data were weighted based on participants' network size. RESULTS: Only 64 (13%) of the 500 MSM in our study reported being circumcised. Among uncircumcised men (n=418), 302 (70.4%) said that they would not be willing to get circumcised even if the procedure could reduce the risk of HIV infection. When considering all participants, circumcision status was not significantly associated with HIV, HBV, HCV, T. pallidum or HPV infections. However, when we restricted the sample to men who do not practice receptive anal intercourse (RAI) and compared circumcised to uncircumcised men, the former (N=33) had no cases of HIV infection, while 34 of 231 (14.8%) uncircumcised men were HIV positive (p=0.020). Regarding HPV, uncircumcised men had a significantly larger number of different HPV types compared with circumcised men (mean 1.83 vs. 1.09, p<0.001) and a higher frequency of high-risk-HPV genotypes (47.6% vs. 12.5%, p=0.012). CONCLUSIONS: Consistent with international evidence, male circumcision appears to have a partial protective effect among MSM. The efficacy of circumcision in reducing risk of HIV infection among MSM appears to be correlated with sexual practices. Given the lack of motivation among MSM with regard to circumcision, proper awareness on the risks and benefits of circumcision needs to be created, if circumcision has to be introduced as a prevention strategy.

Violence as a barrier for HIV prevention among female sex workers in Argentina.

BACKGROUND: Violence against female sex workers (FSWs) has been increasingly reported as an important determinant of HIV infection risk. This study explores the frequency of different violent experiences (sexual abuse, rejection, beating and imprisonment) among FSWs in Argentina and its association with condom use and HIV and T. pallidum prevalence. METHODS: A convenience sample of 1255 FSWs was included in a cross-sectional study conducted between October 2006 and November 2009. RESULTS: Sexual abuse was reported by 24.1% (219/907) of women. A total of 34.7% (42/1234) reported rejection experiences, 21.9% (267/1215) reported having been beaten and 45.4% (561/1236) stated having been arrested because of their sex work activity. There was a higher frequency of inconsistent condom use with clients among FSWs who had experienced sexual abuse, rejection, and police detention. A higher frequency of HIV and T. pallidum infection was detected among FSWs who reported having been arrested by the police. CONCLUSION: The study shows for the first time the frequency of different violent situations among FSWs in Argentina. The association between violence against sex workers, condom use and STI prevalence demonstrated here calls for measures to reduce stigma and violence against FSWs. Such violent experiences may increase vulnerability to STI through coerced unprotected sex.