Background: HIV incidence can be estimated with cross-sectional studies using clinical, serological, and molecular data. Worldwide, HIV incidence data in only men who have sex with men (MSM) are scarce and principally focus on those with healthcare or under treatment. However, better estimates can be obtained through studies with national representativeness. The objective was to estimate the prevalence, incidence, and factors associated with acquiring HIV in a national sample of MSM who attend meeting places, considering geographical regions. Methods: A nationally representative survey of MSM attending meeting places was performed in Mexico. Participants answered a questionnaire, and a dried blood spot (DBS) was collected. Samples were classified as recent infections using an algorithm with HIV status, antiretroviral therapy, and the result of BED-EIA assay. Parameters were analysed considering regions and demographic and sexual behaviour characteristics. Results: The national HIV prevalence was 17.4% with regional differences; the highest prevalence (20.7%) was found in Mexico City, and the lowest prevalence was found in the West region (11.5%). The incidence was 9.4 per 100 p/y, with regional values from 6.2 to 13.2 for the Northeast and the Centre regions, respectively. Age, age at sexual debut, low wealth index, and rewarded sex were associated with HIV prevalence. Centre region, use of private clinics as health services, and having sex exclusively with men were associated with recent HIV infections. Conclusions: The incidence and prevalence showed regional differences, suggesting a difference in the dynamics of HIV transmission; some regions have a greater case accumulation, and others have a greater rate of new infections. Understanding this dynamic will allow developing health programs focused on HIV prevention or treating people already living with HIV.

Men who have sex with men (MSM) are disproportionately affected by syphilis, HIV, and syphilis/HIV coinfection. Antiretroviral therapy (ART) prevents HIV transmission but does not impede the spread or acquisition of syphilis. Information about syphilis/HIV coinfection among MSM is scarce. We aimed to determine the prevalence of syphilis/HIV coinfection in a national sample of MSM who attend meeting places (such as movies, clubs, gay bars, saunas, shopping malls, and others referred to by the same MSM participants of the study) in Mexico to evaluate factors associated with syphilis, and to compare the prevalence rates of syphilis between the current survey and DGE data. We performed a laboratory diagnosis to determine the rates of syphilis and HIV among the included MSM. The national and regional prevalence of syphilis was calculated. HIV and coinfection prevalence were determined only for the survey. All prevalence rates included _95%CIs. Descriptive, bivariate, and multivariate analyses were performed. The national prevalence rates of syphilis, HIV, and coinfection were 15.2%, 10.2%, and 5.7%, respectively. The region with the highest prevalence rate was Mexico City (39.4%). The center region, minimal “goods” (i.e., a minimal number of material possessions such as a car or dryer, etc., which served as a proxy for low economic income level), use of “inhalant drugs”, “HIV infection”, “sexual intercourse” only with men, “rewarded sex”, and “youngest age at first sexual encounter or debut” were risk factors for syphilis. In general, regional prevalence of syphilis was higher in the survey (2013) and DGE data from 2019 than in the DGE data from 2013. Similar to other countries, Mexico needs to assess elements around not only syphilis and HIV infections but also syphilis/HIV coinfection, and preventive measures focusing on MSM are needed.

Much is known about the natural history of syphilis; however, less is known about the immune response against it, and even less is known about people living with HIV (PLWH). Due to the lack of an animal model to study host-pathogen interactions, it remains unclear how the host eliminates the bacteria. Here, we attempt to elucidate the immune response against infection by summarizing all the reported data in a systematic review. We found that only seven papers included PLWH, and they did not accurately describe the immune response against Treponema pallidum since only lymphopenia was reported upon coinfection. On the other hand, at least sixteen papers described the host-pathogen interaction in individual cell populations. Using this information, we established the kinetics of the immune response against syphilis and hypothesized how CD4⁺ T cells, such as Th17 and T rex cells, worsen the progression of the disease in PLWH through their hallmark cytokines, IL-10 and IL-17, and how these two cytokines may play important roles as biomarkers.

Objetivos. Determinar la prevalencia de anticuerpos contra Treponema pallidum y virus herpes simple tipo 2 (VHS-2), así como identificar los factores asociados a dichas infecciones entre migrantes en tránsito en Chiapas, México. Métodos. Estudio transversal realizado durante 2021-2022, en tres albergues para migrantes en Chiapas, México. Las personas contestaron un cuestionario y proporcionaron una muestra de sangre para la detección de anticuerpos contra Treponema pallidum y VHS-2. Se calculó la seroprevalencia y se evaluaron los factores asociados mediante pruebas de χ² y razones de momios. Resultados. Participaron 462 migrantes, con edad promedio de 31,2 años, 56,9 % eran mujeres, 41,1 % provenían de Honduras. La seroprevalencia de VHS-2 fue 29,9 % mientras que la de sífilis fue 4,5 %, siendo mayor en hombres (8,0 %) que en mujeres (1,9 %). El 15,4 % de las embarazadas presentaban anticuerpos contra sífilis. Entre las variables asociadas a sífilis destacan el ser hombre, antecedente de lesiones genitales, así como tener parejas del mismo sexo y la seropositividad a VHS-2. Con relación al VHS-2, factores como ser mujer, edad, escolaridad, dormir en la calle, antecedente de prueba de VIH, debut sexual temprano, número de parejas sexuales y sífilis estuvieron asociados a la infección. Conclusiones. Se encontró una prevalencia elevada de sífilis y VHS-2 entre la población migrante evaluada. La sífilis se confirma como una infección reemergente, incluso en las mujeres. Los migrantes presenta vulnerabilidades asociadas al comportamiento sexual, por lo que se deben enfocar medidas de prevención, diagnóstico y tratamiento para este grupo poblacional.

Adolescents and young people are particularly vulnerable to contracting STIs, including HSV-2; furthermore, vaginal shedding of HSV-2 during pregnancy can cause vertical transmission and neonatal herpes. To evaluate the seroprevalence of HSV-2 and vaginal HSV-2 shedding in adolescent and young pregnant women, a cross-sectional study was carried out in 496 pregnant women—adolescents and young women. Venous blood and vaginal exudate samples were taken. The seroprevalence of HSV-2 was determined by ELISA and Western blot. Vaginal HSV-2 shedding was assessed by qPCR of the HSV-2 UL30 gene. The seroprevalence of HSV-2 in the study population was 8.5% (95% CI 6–11), of which 38.1% had vaginal HSV-2 shedding (95% CI 22–53). Young women presented a higher seroprevalence of HSV-2 (12.1%) than adolescents (4.3%), OR = 3.4, 95% CI 1.59–7.23. Frequent alcohol consumption was significantly associated with HSV-2 seroprevalence, OR = 2.9, 95% CI 1.27–6.99. Vaginal HSV-2 shedding is highest in the third trimester of pregnancy, but this difference is not significant. The seroprevalence of HSV-2 in adolescents and young women is similar to that previously reported in other studies. However, the proportion of women with vaginal shedding of HSV-2 is higher during the third trimester of pregnancy, increasing the risk of vertical transmission.

Objective. To determine the prevalence of SARS-CoV-2 antibodies among healthcare workers (HCW) and to identify factors associated with infection. Materials and meth­ods. A cross-sectional study was conducted in a Covid-19 hospital in Morelos, Mexico. Antibodies against SARS-CoV-2 spike and nucleocapsid proteins were detected by ELISA. A bivariate and multivariable Poisson regression model were performed to identify factors associated with infection. Results. Among all participants, 31% had anti-SARS-CoV-2 antibodies, while only 13.1% had reported a history of positive RT-PCR. Individuals who reported cohabiting with someone with Covid-19, and those who had a previous RT-PCR test, were more likely to be seropositive. Laboratory personnel had the lowest seroprevalence (12.0%), while social workers had the highest (35.7%). Conclusions. The results of this study show the seroprevalence of SARS-CoV-2 antibodies among HCW in a hospital in Mexico, and underline the importance of serological tests for a better estimate of prevalence in health systems where only symptomatic cases are recorded.