Incidence and time-varying predictors of HIV and sexually transmitted infections among male sex workers in Mexico City.

BACKGROUND: Male sex workers are at high-risk for acquisition of sexually transmitted infections (STIs), including human immunodeficiency virus (HIV). We quantified incidence rates of STIs and identified their time-varying predictors among male sex workers in Mexico City. METHODS: From January 2012 to May 2014, male sex workers recruited from the largest HIV clinic and community sites in Mexico City were tested for chlamydia, gonorrhea, syphilis, hepatitis, and HIV at baseline, 6-months, and 12-months. Incidence rates with 95% bootstrapped confidence limits were calculated. We examined potential time-varying predictors using generalized estimating equations for a population averaged model. RESULTS: Among 227 male sex workers, median age was 24 and baseline HIV prevalence was 32%. Incidence rates (per 100 person-years) were as follows: HIV [5.23; 95% confidence interval (CI): 2.15-10.31], chlamydia (5.15; 95% CI: 2.58-9.34), gonorrhea (3.93; 95% CI: 1.88-7.83), syphilis (13.04; 95% CI: 8.24-19.94), hepatitis B (2.11; 95% CI: 0.53-4.89), hepatitis C (0.95; 95% CI: 0.00-3.16), any STI except HIV (30.99; 95% CI: 21.73-40.26), and any STI including HIV (50.08; 95% CI: 37.60-62.55). In the multivariable-adjusted model, incident STI (excluding HIV) were lower among those who reported consistently using condoms during anal and vaginal intercourse (odds ratio = 0.03, 95% CI: 0.00-0.68) compared to those who reported inconsistently using condoms during anal and vaginal intercourse. CONCLUSIONS: Incidence of STIs is high among male sex workers in Mexico City. Consistent condom use is an important protective factor for STIs, and should be an important component of interventions to prevent incident infections.

Performance of ELISA and Western blot to detect antibodies against HSV-2 using dried blood spots.

BACKGROUND AND AIMS: Herpes simplex virus type 2 (HSV-2) is a sexually transmitted agent and is detected worldwide. HSV-2 is the main cause of genital ulcers and is diagnosed mainly with serological tests. The objective of current study was to evaluate the use of DBS samples to detect HSV-2 antibodies using commercial ELISA and Western blot tests. MATERIALS AND METHODS: IgG-G2 ELISA (Human® Diagnostics, Germany) and Western blot IgG/IgM (EUROLINE-WB, Euroimmun® Germany) tests were modified to use DBS samples. Samples were processed by both methods to determine ELISA cutoff points using ROC curves. ELISA was performed with 100µl and the Western blot with 200µl of eluted DBS. A 1:5 dilution was used and the incubation times were increased for the Western blot. RESULTS: 908 DBS samples were processed and the following cutoff points were determined: negative (0-3.79), undetermined (3.8-4.6) and positive (≥4.61), with sensitivity and specificity close to 95%. CONCLUSION: Modifications of the cutoff points of the ELISA test were obtained with technical adjustments done to detect HSV-2 antibodies by ELISA and Western blot using DBS samples.

Heterogeneity of Herpes Simplex Virus Type 2 Seroprevalence From a National Probability Survey In Mexico, 2012.

BACKGROUND: Herpes simplex virus type 2 (HSV-2) seroprevalence and associated infection risk factors show differences by regions and countries. The aims of the study were to determine the HSV-2 seroprevalence and to evaluate the risk factors for HSV-2 in a national representative survey among adolescents and adults in Mexico. METHODS: A cross-sectional study was carried out in Mexico on the basis of the National Health and Nutrition Survey 2012, a national representative survey. Demographic, sexual behavior, reproductive health, and lifestyles indicators were considered in the current study. Participants provided biological samples-dried blood spots-to test for HSV-2 antibodies using enzyme-linked immunosorbent assay and Western blot. Bivariate and multivariate analyses were performed to identify variables associated with HSV-2 infections analyzed by sex. RESULTS: National HSV-2 seroprevalence was 9.9%, 2.4% among adolescents and 11.7% among adults with HSV-2 seroprevalence heterogeneous across the country. Women had 12.2% of antibodies against HSV-2 and men had 7.5%. The factors associated with HSV-2 infection among women were age (45-49 years; odds ratio [OR], 19.8), region (southwest; OR, 3.0), urbanization (urban; OR, 1.9), age at sexual debut (≤14 years; OR, 3.4), education level (any; OR, 3.0), and previous abortion (≥2 abortion; OR, 2.1). Among men, age (45-49 years; OR, 11.7), region (southwest; OR, 3.0), urbanization (urban, odds ratio [OR], 1.7), and HIV care (OR, 7.1) were associated with the infection. CONCLUSIONS: Approximately 10% of Mexicans aged 15 to 49 years had HSV-2 antibodies, with differences by sex, region, education level, urbanization, HIV care, and childbirth, highlighting the relevance of health inequalities in the country: social inequalities seem to matter in terms of the probability of HSV-2 infections.

College women, HPV genotyping and sexual behavior before HPV vaccination: Results from samples stored for a long time.

HPV is the sexually transmitted agent most common among young people, like college students. The aim of study was to associate sexual behavior characteristics of women with HPV, detected in genital samples taken before the introduction of the HPV vaccine. Female students during 2001-2005 donated genital samples and the samples were re-analyzed in 2013 for HPV genotyping by RT-PCR. The frozen storage of the students' genital samples allowed the detection of HPV DNA and its genotyping after years of sample collection. HPV prevalence was 22%, HPV16 3.9%, and HPV18 1.1%. Age, multiple sexual partners and the partner's age at first sexual intercourse were significantly associated to HPV. Students with ≥ 3 sexual partners and who did not use condom had 12.8 higher odds of being HPV positive. These results made possible the analysis of HPV prevalence changes, before HPV vaccine introduction.

Punto Seguro: A Randomized Controlled Pilot Using Conditional Economic Incentives to Reduce Sexually Transmitted Infection Risks in Mexico.

Randomized controlled pilot evaluated effect of conditional economic incentives (CEIs) on number of sex partners, condom use, and incident sexually transmitted infections (STIs) among male sex workers in Mexico City. Incentives were contingent on testing free of new curable STIs and/or clinic attendance. We assessed outcomes for n = 227 participants at 6 and 12 months (during active phase with incentives), and then at 18 months (with incentives removed). We used intention-to-treat and inverse probability weighting for the analysis. During active phase, CEIs increased clinic visits (10-13 percentage points) and increased condom use (10-15 percentage points) for CEI groups relative to controls. The effect on condom use was not sustained once CEIs were removed. CEIs did not have an effect on number of partners or incident STIs. Conditional incentives for male sex workers can increase linkage to care and retention and reduce some HIV/STI risks such as condomless sex, while incentives are in place.

Serological response to Helicobacter pylori infection among Latin American populations with contrasting risks of gastric cancer.

Gastric cancer is a rare outcome of chronic Helicobacter pylori infection. Serologic profiles may reveal bacterial, environmental and/or host factors associated with cancer risk. We therefore compared specific anti-H. pylori antibodies among populations with at least twofold differences in gastric cancer mortality from Mexico, Colombia and Chile. Our study included 1,776 adults (mean age 42 years) from three nationally representative surveys, equally divided between residents of high- and low-risk areas. Antibodies to 15 immunogenic H. pylori antigens were measured by fluorescent bead-based multiplex assays; results were summarized to identify overall H. pylori seropositivity. We used logistic regression to model associations between antibody seroreactivity and regional cancer risk (high vs. low), adjusting for country, age and sex. Both risk areas had similar H. pylori seroprevalence. Residents in high- and low-risk areas were seroreactive to a similar number of antigens (means 8.2 vs. 7.9, respectively; adjusted odds ratio, OR: 1.02, p = 0.05). Seroreactivities to Catalase and the known virulence proteins CagA and VacA were each significantly (p < 0.05) associated with residence in high-risk areas, but ORs were moderate (1.26, 1.42 and 1.41, respectively) and their discriminatory power was low (area under the curve < 0.6). The association of Catalase was independent from effects of either CagA or VacA. Sensitivity analyses for antibody associations restricted to H. pylori-seropositive individuals generally replicated significant associations. Our findings suggest that humoral responses to H. pylori are insufficient to distinguish high and low gastric cancer risk in Latin America. Factors determining population variation of gastric cancer burden remain to be identified.

A Cross-Sectional Study of Prisoners in Mexico City Comparing Prevalence of Transmissible Infections and Chronic Diseases with That in the General Population.

OBJECTIVES: To describe patterns of transmissible infections, chronic illnesses, socio-demographic characteristics and risk behaviors in Mexico City prisons, including in comparison to the general population, to identify those currently needing healthcare and inform policy. MATERIALS AND METHODS: A cross-sectional study among 17,000 prisoners at 4 Mexico City prisons (June to December 2010). Participation was voluntary, confidential and based on informed consent. Participants were tested for HIV, Hepatitis B & C, syphilis, hypertension, obesity, and, if at risk, glucose and cholesterol. A subset completed a questionnaire on socio-demographic characteristics and risk behaviors. Positive results were delivered with counseling and treatment or referral. RESULTS: 76.8% (15,517/20,196) of men and 92.9% (1,779/1,914) of women participated. Complete data sets were available for 98.8%. The following prevalence data were established for transmissible infections: HIV 0.7%; syphilis: Anti-TP+/VDRL+ 2.0%; Hepatitis B: HBcAb 2.8%, HBsAg 0.15%; Anti-HCV 3.2%. Obesity: 9.5% men, 33.8% women. Compared with national age- and sex-matched data, the relative prevalence was greater for HIV and syphilis among women, HIV and Hepatitis C in men, and all infections in younger participants. Obesity prevalence was similar for women and lower among male participants. The prevalence of previously diagnosed diabetes and hypertension was lower. Questionnaire data (1,934 men, 520 women) demonstrated lower educational levels, increased smoking and substance use compared to national data. High levels of non-sterile tattooing, physical abuse and histories of sexual violence were found. CONCLUSION: The study identified that health screening is acceptable to Mexico City prisoners and feasible on a large-scale. It demonstrated higher prevalence of HIV and other infections compared to national data, though low rates compared to international data. Individual participants benefited from earlier diagnosis, treatment and support. The data collected will also enable the formulation of improved policy for this vulnerable group.

Comparative Estimates of Crude and Effective Coverage of Measles Immunization in Low-Resource Settings: Findings from Salud Mesoamérica 2015.

Timely and accurate measurement of population protection against measles is critical for decision-making and prevention of outbreaks. However, little is known about how survey-based estimates of immunization (crude coverage) compare to the seroprevalence of antibodies (effective coverage), particularly in low-resource settings. In poor areas of Mexico and Nicaragua, we used household surveys to gather information on measles immunization from child health cards and caregiver recall. We also collected dried blood spots (DBS) from children aged 12 to 23 months to compare crude and effective coverage of measles immunization. We used survey-weighted logistic regression to identify individual, maternal, household, community, and health facility characteristics that predict gaps between crude coverage and effective coverage. We found that crude coverage was significantly higher than effective coverage (83% versus 68% in Mexico; 85% versus 50% in Nicaragua). A large proportion of children (19% in Mexico; 43% in Nicaragua) had health card documentation of measles immunization but lacked antibodies. These discrepancies varied from 0% to 100% across municipalities in each country. In multivariate analyses, card-positive children in Mexico were more likely to lack antibodies if they resided in urban areas or the jurisdiction of De Los Llanos. In contrast, card-positive children in Nicaragua were more likely to lack antibodies if they resided in rural areas or the North Atlantic region, had low weight-for-age, or attended health facilities with a greater number of refrigerators. Findings highlight that reliance on child health cards to measure population protection against measles is unwise. We call for the evaluation of immunization programs using serological methods, especially in poor areas where the cold chain is likely to be compromised. Identification of within-country variation in effective coverage of measles immunization will allow researchers and public health professionals to address challenges in current immunization programs.

The disproportionate burden of HIV and STIs among male sex workers in Mexico City and the rationale for economic incentives to reduce risks.

INTRODUCTION: The objective of this article is to present the rationale and baseline results for a randomized controlled pilot trial using economic incentives to reduce HIV and sexually transmitted infection (STI) risk among male sex workers (MSWs) in Mexico City. METHODS: Participants (n=267) were tested and treated for STIs (chlamydia, gonorrhoea, syphilis and HIV) and viral hepatitis (hepatitis B and C), received HIV and STI prevention education and were randomized into four groups: (1) control, (2) medium conditional incentive ($50/six months), (3) high conditional incentive ($75/six months) and (4) unconditional incentive ($50/six months). In the conditional arms, incentives were contingent upon testing free of new curable STIs (chlamydia, gonorrhoea and syphilis) at follow-up assessments. RESULTS: Participants' mean age was 25 years; 8% were homeless or lived in a shelter, 16% were unemployed and 21% lived in Mexico City less than 5 years. At baseline, 38% were living with HIV, and 32% tested positive for viral hepatitis or at least one STI (other than HIV). Participants had a mean of five male clients in the previous week; 18% reported condomless sex with their last client. For 37%, sex work was their main occupation and was conducted mainly on the streets (51%) or in bars/discotheques (24%) and hotels (24%). The average price for a sex transaction was $25 with a 35% higher payment for condomless sex. CONCLUSIONS: The findings suggest that economic incentives are a relevant approach for HIV prevention among MSWs, given the market-based inducements for unprotected sex. This type of targeted intervention seems to be justified and should continue to be explored in the context of combination prevention efforts.

Risk factors for anal HPV-16/18 infection in Mexican HIV-infected men who have sex with men.

OBJECTIVE: To describe the prevalence of specific HPV types among HIV-positive men who have sex with men (MSM), particularly the presence of HPV-16 and/or -18, and to determine the factors associated with anal HPV-16/18 infections. METHODS: This is a cross-sectional study from a baseline cohort of 525 HIV-positive MSM, who attended an HIV Clinic in Mexico City. Socio-demographic characteristics, sexual behaviors and HIV-related parameters were assessed. Anal samples were tested for HPV DNA using the Linear Array HPV genotyping assay. RESULTS: The overall prevalence of any HPV type in the anal canal among 446 participants was 93.1%. At least one oncogenic HPV type was detected in 72.2% of the subjects and HPV-16 and/or18 were detected in 30.7%. Additionally, 76.9% of patients were infected with multiple HPV types. Having more than 10 receptive sexual partners in the last 6months (OR=2.30; 95% CI 1.12-4.74) and a CD4 cell count ≤350cells/µL (OR=1.97; 95% CI 1.26-3.09) were factors positively associated with HPV-16/18 infection in the anal canal. CONCLUSION: Co-infection with HPV-16/18 and other oncogenic types are predominant in this group of HIV-positive MSM. The recognition of infection with specific oncogenic types will be of aid in designing future preventive strategies that target this high-risk population.

Diagnostic-test evaluation of immunoassays for anti-Toxoplasma gondii IgG antibodies in a random sample of Mexican population.

INTRODUCTION: There are few articles on evaluation of Toxoplasma gondii serological tests. Besides, commercially available tests are not always useful and are expensive for studies in open population. The aim of this study was to evaluate in-house ELISA and western blot for IgG antibodies in a representative sample of people living in Mexico. METHODOLOGY: Three hundred and five serum samples were randomly selected from two national seroepidemiological survey banks; they were taken from men and women of all ages and from all areas of the country. ELISA cut-off was established using the mean plus three standard deviations of negative samples. Western blots were analysed by two experienced technicians and positivity was established according to the presence of at least three diagnostic bands. A commercial ELISA kit was used as a third test. Two reference standards were built up: one using concordant results of two assays leaving the evaluated test out and the other in which the evaluated test was included (IN) with at least two concordant results to define diagnosis. RESULTS: the lowest values of diagnostic parameters were obtained with the OUT reference standards: in-house ELISA had 96.9% sensitivity, 62.1% specificity, 49.6% PPV, 98.1% NPV and 71.8% accuracy, while western blot presented 81.8%, 89.7%, 84.0%, 88.2% and 86.6% values and the best kappa coefficient (0.72-0.82). CONCLUSIONS: The in-house ELISA is useful for screening people of Mexico, due to its high sensitivity, while western blot may be used to confirm diagnosis. These techniques might prove useful in other Latin American countries.

Is the HIV epidemic stable among MSM in Mexico? HIV prevalence and risk behavior results from a nationally representative survey among men who have sex with men.

BACKGROUND: Recent evidence points to the apparent increase of HIV prevalence among men who have sex with men (MSM) in different settings with concentrated epidemics, including the Latin American region. In 2011, Mexico implemented an ambitious HIV prevention program in all major cities, funded by the Global Fund to Fight Aids, Tuberculosis and Malaria. The program was intended to strengthen the prevention response for the most at risk populations: MSM and injecting drug users. This paper presents the HIV prevalence results of a nationally representative baseline survey in 24 Mexican cities throughout the 5 regions in the country and reports the socio-demographic and sexual risk behaviors that predict the probability of infection. METHODS: The survey was implemented in two phases. We first identified and characterized places where MSM gather in each city and then conducted in a second phase, a seroprevalence survey that included rapid HIV testing and a self-administered questionnaire. The prevalence of HIV was estimated by adjusting for positive predicted value. We applied a probit model to estimate the probability of having a positive result from the HIV test as a function of socio-demographic characteristics and self-reported sexual risk behaviors. RESULTS: We found an overall HIV prevalence among MSM gathering in meeting points of 16.9% [95% CI: 15.6-18.3], significantly higher than previously reported estimates. Our regression results suggest that the risk of infection increases with age, with the number of sexual partners, and among those who play a receptive sexual role, and the risk decreases with higher education. DISCUSSION: Our findings suggest a higher HIV prevalence among MSM than previously acknowledged and that a significant regional variability exist throughout the country. These two findings combined, signal an important dynamic in the epidemic that should be better understood and promptly addressed with strong prevention efforts targeted at key populations.

Seroprevalence and national distribution of human toxoplasmosis in Mexico: analysis of the 2000 and 2006 National Health Surveys.

Global warming has had serious implications on dispersion of infectious diseases like toxoplasmosis. Since the frequency of Toxoplasma gondii largely depends on climatic conditions, we studied its prevalence by means of 3599 samples of the National Health Survey 2000 (NHS-2000) and 2916 of the National Health and Nutrition Survey 2006 (NHNS-2006) serum banks, obtained from 1-98 year old subjects of both genders and all states of Mexico. Anti-T.gondii IgG antibodies were determined by ELISA and confirmed by western blot. Crude, epidemiologically weighted and diagnosis-performance-adjusted prevalence values were calculated. Seroprevalence changes were compared between both surveys and among regions (north, center and coast). Also, correlations between changes in temperature or humidity and those in prevalence were measured. National crude prevalence was 60.1% and 62.6% for NHS-2000 and NHNS-2006, respectively. Weighted and adjusted values were 62.5% and 40.0% for NHS-2000, and 63.7 and 43.1% for NHNS-2006. Coastal states and children presented the largest increases between surveys, while the center of the country showed a decrease. An apparently higher prevalence of T. gondii infection was observed in both surveys compared to that performed in 1987, while a geographical re-distribution was found from 2000 to 2006, with a positive correlation between temperature and frequency deltas in 21 states where prevalence increased.

Human papillomavirus incidence and risk factors among Mexican female college students.

OBJECTIVE: To determine the factors associated with high-risk human papillomavirus (HR-HPV) and its incidence in a cohort of female college students, with particular emphasis on the use of condoms. METHODS: A cohort was created during 2001 to 2005. The students signed informed consent, answered a questionnaire, and provided a vaginal scrape to detect HR-HPV. Incidences were estimated and risk factors were evaluated using Cox proportional risk model. The variable condom use was constructed based on the following 3 measurements: relative frequency throughout one's lifetime, use during the first sexual relationship, and use during the last sexual relationship. RESULTS: A total of 237 women participated, providing 395.6 person-years of follow-up. An incidence of 15.9 HR-HPV infection per 100 person-years was estimated and the factors associated with HR-HPV infection were found to be self-reported sexually transmitted infections (RR = 2.7), use of emergency contraception pill (ECP) (RR = 2.0), and having 2 or more sexual partners (RR = 1.9). University students using the ECP demonstrated more risky sexual behavior than nonusers. Women with 2 or more sexual partners who reported inconsistent condom use had 3.8 times the rate of HR-HPV infection. CONCLUSIONS: The incidence for HR-HPV in this cohort of Mexican female college students is comparable to that found in the United States and Canada. The results suggest that the consistent use of condoms is a protective factor against HR-HPV, especially for women with multiple sexual partners and/or those who use the ECP.

Serological protection induced by Haemophilus influenzae Type B conjugate vaccine in Mexican children: is a booster dose of the vaccine needed?

We determined the seroprevalence of protective antibodies against Hib in Mexican children under the age of five using a standardized enzyme-linked immunosorbent assay. Hib antibodies (≥ 0.15 µg/ml) were present in 95.34% (±1.14% [seroprevalence ± standard error]) of samples. Fewer children aged 30 to 47 months had protective Hib antibody levels (91.45% ± 2.60%) than children from 12 to 29 and 48 to 59 months (97.3% ± 1.34% and 97.44% ± 1.80%, respectively).

[Evaluation of a rapid diagnostic test to assess the prevalence of maternal syphilis in Bolivia]. / Prevalencia de sífilis materna y evaluación de una prueba diagnóstica rápida en Cochabamba, Bolivia.

BACKGROUND: Syphilis is still a public health problem in Latin America and the Caribbean. Therefore maternal screening is of great importance for public health. AIM: To estimate the prevalence of maternal syphilis and to evaluate a rapid diagnostic test for the disease among Bolivian women. MATERIAL AND METHODS: A total of 489 women delivering in a Public Hospital in Cochabamba, Bolivia, answered a questionnaire about socioeconomic and reproductive characteristics and access to health care services. Syphilis was diagnosed by using RPR and FTA-ABS tests. The rapid test Determine syphilis TP was evaluated taking as reference FTA-ABS test. RESULTS: Twenty two women (4.5%) were positive both for RPR and FTA-ABS tests and fifty (10.2%) were positive for the rapid diagnostic test and FTA-ABS. Compared with FTA-ABS, the sensitivity and specificity of the rapid test were 98% and 99.8%, respectively Only 15% of women that had at least one antenatal care visit had a syphilis screening test and 40% of the women in whom the test was performed, did not receive its results. Increasing age, low socioeconomic level and a history of a sexually transmitted disease were independently associated with syphilis infection. CONCLUSIONS: The magnitude of syphilis infection among the studied women was still high in Cochabamba. The rapid test showed excellent overall performance for maternal syphilis screening. Few women of all attended in the hospital had a screening syphilis test and half of those screened were not aware of the results. Maternal syphilis affected older women of low socioeconomic level and with a history of a sexually transmitted disease.

Prevalencia de sífilis materna y evaluación de una prueba diagnóstica rápida en Cochabamba, Bolivia / Evaluation of a rapid diagnostic test to assess the prevalence of maternal syphilis in Bolivia

Background: Syphilis is still a public health problem in Latin America and the Caribbean. Therefore maternal screening is of great importance for public health. Aim: To estimate the prevalence of maternal syphilis and to evaluate a rapid diagnostic test for thedisease among Bolivian women. Material and methods: A total of 489 women delivering in a Public Hospital in Cochabamba, Bolivia, answered a questionnaire about socioeconomic andreproductive characteristics and access to health care services. Syphilis was diagnosed by using RPR and FTA-ABS tests. The rapid test Determine syphilis TP was evaluated taking as reference FTA-ABS test. Results: Twenty two women (4.5%) were positive both for RPR and FTA-ABS tests and fifty (10.2%) were positive for the rapid diagnostic test and FTA-ABS. Compared with FTA-ABS, the sensitivity and specificity of the rapid test were 98% and 99.8%, respectively. Only 15% of women that had at least one antenatal care visit had a syphilis screening test and 40% of the women in whom the test was performed, did not receive its results. Increasing age, low socioeconomic level and a history of a sexually transmitted disease were independently associated with syphilis infection. Conclusions: The magnitude of syphilis infection among the studied women was still high in Cochabamba. The rapid test showed excellent overall performance for maternal syphilis screening. Few women of all attended in the hospital had a screening syphilis test and half of those screened were not aware of the results. Maternal syphilis affected older women of low socioeconomic level and with a history of a sexually transmitted disease.

Population-based prevalence of antibodies against herpes simplex virus type 2 and socio-demographic characteristics in Mexico.

Although several studies to evaluate the correlates between seroprevalence of herpes simplex virus type 2 (HSV-2) and sexual practices have been carried out with specific groups in Mexico, none has evaluated overall seroprevalence among the general population or its relationship with socio-demographic characteristics. The National Health Survey performed during 2000 in Mexico studied a multi-stage, stratified, cluster sample of the general population. Characteristics of the adult population, such as age, formal education, marital status, residence, age at first intercourse and categories of HSV-2 seroprevalence distribution by state, were studied. Specific antibodies against HSV-2 were determined by ELISA. The weighted seroprevalence of HSV-2 was 17.3% (95% CI 15.8-18.8) and showed significant variations according to age, sex, marital status, residence, age at first intercourse and categories of HSV-2 seroprevalence distributed by state. In conclusion, the prevalence of HSV-2 varied significantly according to the socio-demographic and geographic characteristics of the adult population in Mexico. These results suggest that variations in HSV-2 seroprevalence could be related to socio-economic and sexual behavior characteristics of the population. However, to support these assertions, further work could focus on the study of sexual behavior and its relation with the socio-economic distribution of the population in Mexico.

Different patterns of herpes simplex virus type 1 infection among college students from Cuernavaca, Mexico.

The goal of this study was to determine herpes simplex virus type 1 (HSV-1) seroprevalence among college students from Morelos State University, Mexico; and to correlate their demographic and sexual behaviour characteristics with HSV-1 infection. Demographic characteristics were associated with HSV-1 among female students. Among male students, sexual behaviour characteristics were associated with HSV-1 seroprevalence. Male students who practised oral sex and did not always use a condom presented higher rates of HSV-1 infection (76.9%) than students who did not have oral sex (52.2%). A different pattern of HSV-1 infection depends on gender among Mexican students analysed.

Core group approach to identify college students at risk for sexually transmitted infections

OBJETIVO: Identificar al grupo core de infecciones de transmisión sexual (ITS) en una población de estudiantes universitarios mexicanos. MÉTODOS: Se realizó un estudio transversal en una muestra por conveniencia que incluyó 711 estudiantes de una universidad pública de Morelos, México, entre 2001 y 2003. Las características sociodemográficas y de comportamiento sexual se obtuvieron mediante un cuestionario auto-aplicado. La infección por el Virus del herpes simple tipo 2 (VHS-2) se determinó en pruebas de sangre. El número de parejas sexuales durante el último año y el consumo de cocaína, fueron indicadores utilizados para construir la variable dependiente "nivel de riesgo para adquirir ITS" que tuvo tres categorías: bajo, medio y alto riesgo (grupo core). Mediante un análisis multinomial se evaluó si las características sociodemográficas y de comportamiento sexual estuvieron relacionadas con la variable dependiente. RESULTADOS: Se encontró una relación significativa entre la seroprevalencia de VHS-2 y la variable dependiente encontrando frecuencias de 13 por ciento, 5.6 por ciento y 3.8 por ciento en las categorías de alto, medio y bajo riesgo, respectivamente. Los resultados mostraron diferencias de género en la constitución del grupo core. En comparación con las mujeres, los hombres iniciaron su vida sexual a más temprana edad, reportaron mayor número de parejas sexuales, mayores niveles de consumo de alcohol y drogas, mayor frecuencia de contacto sexual con trabajadoras sexuales, intercambio de sexo por dinero, relaciones con parejas ocasionales y concurrentes. CONCLUSIONES: Los resultados sugieren que existen características contextuales que influyen en el comportamiento sexual. En México la concepción cultural de la sexualidad está conformada por diferencias marcadas entre hombres y mujeres, donde los primeros tienen un comportamiento sexual de riesgo mayor que las mujeres.