Alfonso Silva-Santisteban
Cayetano Heredia University
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Featured researches published by Alfonso Silva-Santisteban.
The Lancet | 2015
Tonia Poteat; Andrea L. Wirtz; Anita Radix; Annick Borquez; Alfonso Silva-Santisteban; Madeline B. Deutsch; Sharful Islam Khan; Sam Winter; Don Operario
Worldwide, transgender women who engage in sex work have a disproportionate risk for HIV compared with natal male and female sex workers. We reviewed recent epidemiological research on HIV in transgender women and show that transgender women sex workers (TSW) face unique structural, interpersonal, and individual vulnerabilities that contribute to risk for HIV. Only six studies of evidence-based prevention interventions were identified, none of which focused exclusively on TSW. We developed a deterministic model based on findings related to HIV risks and interventions. The model examines HIV prevention approaches in TSW in two settings (Lima, Peru and San Francisco, CA, USA) to identify which interventions would probably achieve the UN goal of 50% reduction in HIV incidence in 10 years. A combination of interventions that achieves small changes in behaviour and low coverage of biomedical interventions was promising in both settings, suggesting that the expansion of prevention services in TSW would be highly effective. However, this expansion needs appropriate sustainable interventions to tackle the upstream drivers of HIV risk and successfully reach this population. Case studies of six countries show context-specific issues that should inform development and implementation of key interventions across heterogeneous settings. We summarise the evidence and knowledge gaps that affect the HIV epidemic in TSW, and propose a research agenda to improve HIV services and policies for this population.
Aids and Behavior | 2012
Alfonso Silva-Santisteban; H. Fisher Raymond; Ximena Salazar; Jana Villayzán; Segundo R. Leon; Willi McFarland; Carlos F. Caceres
In Latin America, transgender women (transwomen or male to female transgenders) have been included in MSM research but without addressing their specific needs in terms of the HIV/AIDS. We present results of the first seroepidemiologic study designed for transwomen in Peru. We conducted a study using respondent driven sampling to recruit transwomen from Lima. Our survey explored sociodemographic characteristics, gender enhancement procedures and sexual behavior. In addition, we conducted laboratory based HIV, genital herpes (HSV2) and syphilis testing. A total of 450 transwomen were recruited between April and July 2009. HIV prevalence was 30%, HSV2: 79% and syphilis: 23%. Sex-work was the main economic activity (64%). Gender enhancement procedures were reported by 70% of the population. Multivariable analysis showed HIV infection to be associated with being older than 35 recent, syphilis infection and HSV2 infection. Transwomen are the group most vulnerable to HIV/AIDS in Peru.ResumenEn Latinoamérica, las mujeres trans (personas trans de masculino a femenino) han sido incluídas en la investigación con población HSH sin abordar sus necesidades específicas en relación a la epidemia de VIH/SIDA. Presentamos los resultados del primer estudio sero-epidemiológico diseñado para mujeres trans en el Perú. Utilizamos un diseño transversal con respondent driven sampling (RDS). Las características socio-demográficas de la población, los procesos de transformación del cuerpo y las conductas sexuales fueron exploradas a través de una entrevista. Se realizaron pruebas de laboratorio para VIH, herpes genital (HSV2) y sífilis. Un total de 450 mujeres trans fueron enroladas en Lima entre abril y junio del 2009. La prevalencia de VIH encontrada fue de 30%, HSV2: 79% y sífilis: 23%. El trabajo sexual fue la principal actividad económica reportada (64%). Los procesos de modificación del cuerpo fueron reportados por el 70% de la población. El análisis mutivariable asoció la infección por VIH a una edad mayor a 35 años, la infección reciente por sífilis y la infección con HSV2. Este estudio muestra que las mujeres trans constituyen la población con mayor vulnerabilidad al VIH en el Perú.
Aids and Behavior | 2013
Lisa G. Johnston; Yea-Hung Chen; Alfonso Silva-Santisteban; H. Fisher Raymond
For studies using respondent driven sampling (RDS), the current practice of collecting a sample twice as large as that used in simple random sampling (SRS) (i.e. design effect of 2.00) may not be sufficient. This paper provides empirical evidence of sample-to-sample variability in design effects using data from nine studies in six countries among injecting drug users, female sex workers, men who have sex with men and male-to-female transgender (MTF) persons. We computed the design effect as the variance under RDS divided by the variance under SRS for a broad range of demographic and behavioral variables in each study. We also estimated several measures for each variable in each study that we hypothesized might be related to design effect: the number of waves needed for equilibrium, homophily, and mean network size. Design effects for all studies ranged from 1.20 to 5.90. Mean design effects among all studies ranged from 1.50 to 3.70. A particularly high design effect was found for employment status (design effect of 5.90) of MTF in Peru. This may be explained by a “bottleneck”—defined as the occurrence of a relatively small number of recruitment ties between two groups in the population. A design effect of two for RDS studies may not be sufficient. Since the mean design effect across all studies was 2.33, an effect slightly above 2.00 may be adequate; however, an effect closer to 3.00 or 4.00 might be more appropriate.
Journal of Acquired Immune Deficiency Syndromes | 2015
Rostislav Castillo; Kelika A. Konda; Leon; Alfonso Silva-Santisteban; Ximena Salazar; Jeffrey D. Klausner; Thomas J. Coates; Carlos F. Caceres
Background:Men who have sex with men (MSM) and male-to-female transgender women (TW) are at increased risk of HIV and sexually transmitted infections (STIs). We evaluated factors associated with incidence of HIV, HSV-2, and chlamydia and gonorrhea (anal and pharyngeal). Methods:We used data from the Comunidades Positivas trial with MSM/TW who have sex with men in Lima, Peru. Participants were asked about sexual risk behaviors and underwent HIV/STI testing at baseline and 9- and 18-month follow-ups. We used discrete time proportional hazards regression to calculate hazard ratios for variables associated with incidence of each STI. Results:Among 718 MSM/TW, HIV incidence was 3.6 cases per 100 person-years. HIV incidence was associated with having an incident STI adjusted hazard ratio (aHR) of 3.73. Unprotected receptive anal intercourse was associated with incident anal chlamydia (aHR 2.20). An increased number of sexual partners increased incident HSV-2 (aHR 3.15 for 6–14 partners and 3.97 for 15–46 partners compared with 0–2 partners). The risk of anal gonorrhea decreased with each sexually active year (aHR 0.94) and increased for unprotected compensated sex (aHR 2.36). The risk of pharyngeal gonorrhea also decreased with each year since sexual debut (aHR 0.95). The risk of anal chlamydia decreased with each sexually active year (aHR 0.96); the risk increased with reports of unprotected sex work (aHR 1.61) and unprotected receptive anal sex (aHR 2.63). All aHRs have P values <0.05. Conclusions:MSM/TW experience high incidence of HIV. Up-to-date prevalence and incidence information and identifying factors associated with infection can help develop a more effective combination prevention response.
International Journal of Std & Aids | 2016
Jeremy Y. Chow; Kelika A. Konda; Annick Borquez; Patricia Caballero; Alfonso Silva-Santisteban; Jeffrey D. Klausner; Carlos F. Caceres
The HIV epidemic in Peru is concentrated in men who have sex with men (MSM) and transgender women (TW), who have an estimated prevalence > 10%, while the overall population prevalence remains < 1%. Because MSM and TW account for >60% of new infections, it is crucial to understand the full HIV continuum of care for these key populations. We performed a review of the peer-reviewed scientific and grey literature to determine the proportion of HIV-infected MSM and TW in Peru who are diagnosed, linked to and retained in care, are taking antiretroviral therapy (ART), and who have attained virologic suppression. Of the estimated 613,080 MSM and TW in Peru in 2015, approximately 63,981 are HIV-infected. Only 24.0% of HIV-infected MSM and TW are aware of their diagnosis, 15.6% are retained in care, 13.6% are on ART, and 12.0% have achieved adequate virologic control. The largest drop-off in the HIV care continuum occurs at the first step: diagnosis of HIV. Improving HIV serostatus awareness among MSM and TW is crucial to controlling Peru’s HIV epidemic. In the era of ‘treatment as prevention’, understanding the full HIV care continuum may help guide efforts to curb transmission and reduce HIV-related morbidity and mortality.
Journal of the International AIDS Society | 2017
Amaya Perez-Brumer; Sari L. Reisner; Sarah McLean; Alfonso Silva-Santisteban; Leyla Huerta; Kenneth H. Mayer; Jorge Sanchez; Jesse L. Clark; Matthew J. Mimiaga; Javier R. Lama
Introduction: In Peru, transgender women (TW) experience unique vulnerabilities for HIV infection due to factors that limit access to, and quality of, HIV prevention, treatment and care services. Yet, despite recent advances in understanding factors associated with HIV vulnerability among TW globally, limited scholarship has examined how Peruvian TW cope with this reality and how existing community‐level resilience strategies are enacted despite pervasive social and economic exclusion facing the community. Addressing this need, our study applies the understanding of social capital as a social determinant of health and examines its relationship to HIV vulnerabilities to TW in Peru.
Globalization and Health | 2013
Alfonso Silva-Santisteban; Eddy R. Segura; Clara Sandoval; Maziel Giron; Margarita Petrera; Carlos F. Caceres
BackgroundEquity in access to health care among people living with HIV (PLHA) has not been extensively studied in Peru despite the fact there is significant social diversity within this group. We aimed to assess the extent to which health care provision to PLHA, including ARVT, was equitable and, if appropriate, identify factors associated with lower access.MethodsWe conducted a survey among adult PLHA in four cities in Peru, recruited through respondent-driven sampling (RDS), to collect information on socio-demographic characteristics, social network size, household welfare, economic activity, use of HIV-related services including ARV treatment, and health-related out-of-pocket expenses.ResultsBetween September 2008 and January 2009, 863 individuals from PLHA organizations in four cities of Peru were enrolled. Median age was 35 (IQR = 29–41), and mostly male (62%). Overall, 25% reported to be gay, 11% bisexual and 3% transgender. Most PLHA (96%) reported access to some kind of HIV-related health service, and 84% were receiving those services at a public facility. Approximately 85% of those reporting access to care were receiving antiretroviral treatment (ARV), and 17% of those not in treatment already had indication to start treatment. Among those currently on ARV, 36% percent reported out-of-pocket expenses within the last month. Transgender identity and age younger than 35 years old, were associated with lower access to health care.ConclusionsOur findings contribute to a better social and demographic characterization of the situation of PLHAs, their access to HIV care and their source of care, and provide an assessment of equity in access. In the long term, it is expected that HIV care access, as well as its social determinants, will impact on the morbidity and mortality rates among those affected by the HIV/AIDS epidemic. HIV care providers and program managers should further characterize the barriers to healthcare access and develop strategies to resolve them by means of policy change, for the benefit of the health service users and as part of the national response to the HIV/AIDS epidemic within a human rights framework.
Global Public Health | 2010
Carlos F. Caceres; Girón Jm; Clara Sandoval; López R; Rocío Valverde; Pajuelo J; Vásquez P; Rosasco Am; Chirinos A; Alfonso Silva-Santisteban
Abstract The emergence of opportunities for support from the Global Fund to Fight AIDS, Tuberculosis and Malaria (GFATM) for HIV-related projects has so far generated funding of over US
BMJ Open | 2016
Segundo R. Leon; Eddy R. Segura; Kelika A. Konda; Juan A Flores; Alfonso Silva-Santisteban; Jerome T Galea; Thomas J. Coates; Jeffrey D. Klausner; Carlos F. Caceres
75 million for three proposals in Peru. The size of this investment creates the need for close monitoring to ensure a reasonable impact. This paper describes the effects of collaboration with the GFATM on key actors involved in HIV-related activities and on decision-making processes; on health sector divisions; on policies and sources of financing; on equity of access; and on stigma and discrimination of vulnerable and affected populations. Data analysed included primary data collected through interviews with key informants, in-depth interviews and group discussions with vulnerable and affected populations, as well as several public documents. Multisectorality, encouraged by the GFATM, is incipient; centralist proposals with limited consultation, a lack of consensus and short preparation times prevail. No accountability mechanisms operate at the Country Coordinating Mechanism (CCM) level regarding CCM members or society as a whole. GFATM-funded activities have required significant input from the public sector, sometimes beyond the capacity of its human resources. A significant increase in HIV funding, in absolute amounts and in fractions of the total budget, has been observed from several sources including the National Treasury, and it is unclear whether this has implied reductions in the budget for other priorities. Patterns of social exclusion of people living with HIV/AIDS are diverse: children and women are more valued; while transgender persons and sex workers are often excluded.
Global Public Health | 2016
Andres Maiorana; Susan M. Kegeles; Ximena Salazar; Kelika A. Konda; Alfonso Silva-Santisteban; Carlos F. Caceres
Objectives This study aimed to characterise the epidemiology of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections among men who have sex with men (MSM) and transgender women (TW) in Lima, Peru. Setting Cross-sectional study in Lima, Peru. Participants We recruited a group of 510 MSM and 208 TW for a subsequent community-based randomised controlled trial. The presence of CT and NG were evaluated using Aptima Combo2 in pharyngeal and anal swabs. We also explored correlates of these infections. Primary and secondary outcome measures: Study end points included overall prevalence of C. trachomatis and N. gonorrhoeae in anal and pharyngeal sites. Results Overall prevalence of CT was 19% (95% CI 16.1% to 22.1%) and 4.8% (95% CI 3.3% to 6.6%) in anal and pharyngeal sites, respectively, while prevalence of NG was 9.6% (95% CI 7.5% to 12.0%) and 6.5% (95% CI 4.8% to 8.5%) in anal and pharyngeal sites, respectively. Conclusions The prevalence of each infection declined significantly among participants older than 34 years (p<0.05). Efforts towards prevention and treatment of extraurogenital chlamydial and gonococcal infections in high-risk populations like MSM and TW in Lima, Peru, are warranted. Trial registration number NCT00670163; Results.