Prevention and control of neoplasms associated with HPV in high-risk groups in Mexico City: The Condesa Study.

OBJECTIVE: To evaluate the effectiveness of a combined strategy of human papillomavirus virus (HPV) vaccination and high-risk HPV screening to reduce the occurrence of anogenital and oropharyngeal neoplasms among men who have sex with men, people with HIV, homeless people, transgender women, female sex workers and rape victims. MATERIALS AND METHODS: This mixed methods study evaluates the effectiveness of a combined vaccination-screening strategy to reduce HPV prevalence/incidence and occurrence of cervical intraepithelial neoplasms grade 2+ and/or anal intraepithelial neoplasms grade 2+, using Kaplan-Meier. The time-to-event method will evaluate time from positive results for specific anogenital HPV to incidence of anogenital lesions containing that HPV type. RESULTS: People vaccinated against HPV and screened for HPV as a primary test will have lower prevalence and incidence of HPV infection and consequently lower frequency of HPV-related anogenital and oropharyngeal lesions. CONCLUSIONS: Thisstudy will generate scientific evidence on effectiveness of a combined vaccination-screening strategy to reduce the burden of HPV-associated neoplasms.

OBJETIVO: Evaluar la efectividad de una estrategia combinada de vacunación contra el virus de papiloma humano (VPH) y tamizaje de VPH de alto riesgo para reducir neoplasias anogenitales y orofaringeas entre hombres que tienen sexo con hombres, personas con VIH, personas en situación de calle, mujeres transgénero, trabajadoras sexuales y víctimas de violación. MATERIAL Y MÉTODOS: Este estudio evaluará la efectividad de una estrategia combinada de vacunación y tamizaje para reducir la ocurrencia de neoplasias intraepiteliales cervicales grado 2+ o neoplasias intraepiteliales anales grado NIA2+ utilizando Kaplan-Meier. Se evaluará tiempo de resultados positivos para tipos específicos deVPH anogenital a incidencia de lesiones anogenitales con ese tipo de VPH. RESULTADOS: Las personas vacunadas contra VPH y con tamizaje de VPH tendrán menor prevalencia e incidencia de infecciones por VPH y por ende menor frecuencia de lesiones anogenitales y orofaringeas relacionadas con VPH. CONCLUSIONES: Este estudio generará evidencia científica sobre la efectividad de una estrategia combinada de vacunación y tamizaje para reducir la carga de neoplasias asociadas al VPH.

[Decrease of HCV seroprevalence in Mexico: Results from the National Health and Nutrition Survey 2012]. / Disminución de la seroprevalencia de hepatitis C en México: resultados de la Ensanut 2012.

OBJECTIVE: To estimate seroprevalence of hepatitis C virus (HCV) among 15-49 years old Mexicans living in households and to describe the profile of seroreactive individuals. MATERIALS AND METHODS: Cross-sectional study implemented in 2012 using a national probabilistic sample with behavioral data from face-to-face interviews at households and HCV antibodies screening using capillary blood from same individuals. RESULTS: HCV seroprevalence in Mexico was estimated at 0.27% (IC95% 0.12-0.60), representing 161 000 persons. Seroprevalence was significantly higher among males (0.45% CI95% 0.01-0.89) than females (0.10% CI95% 0.00-0.22). Multivariate analysis suggests a higher possibility of HCV reactivity among men, increasing with age and higher among those sexually active, and lower for higher socioeconomic level. CONCLUSION: HCV seroprevalence in Mexico by 2012 seems significantly lower than the estimation from 2000 of 1.2% for the same age-group. Evidence of infection among individuals 15-19 years old suggests the need to strength preventive actions, particularly in subjects with risky behaviors.

[HIV seroprevalence among Mexicans age 15 to 49: results from the National Health & Nutrition Survey 2012]. / Seroprevalencia de VIH en población mexicana de entre 15 y 49 años: resultados de la Ensanut 2012.

OBJECTIVE: To estimate the HIV seroprevalence among Mexicans aged 15 to 49 years old and living in households, and to describe the profile of serorreactive individuals. MATERIALS AND METHODS: Cross-sectional study with a national probabilistic sample of individuals aged 15 to 49 years with behavioral data from direct interview (face-to-face) at households and HIV screening using capillary blood collected from the same individuals. RESULTS: A seroprevalence of 0.15% (95%CI 0.09-0.21) was estimated for Mexicans aged 15 to 49; seroprevalence among women was 0.07% (95%CI 0.03-0.11) and 0.24% (95%CI 0.11-0.36) for men. HIV serorreactive population is composed of younger men, with a higher socioeconomic level compared to the general population, and with a higher insurance coverage-social protection on health in general and social security in particular. Only 50% of the serorreactive individuals may be aware of their status as living with HIV. CONCLUSIONS: The estimated HIV seroprevalence in the NHNS 2012 suggests a stable pattern since 2000. The estimated prevalence among individuals 15 to 49 years was adjusted both for selection bias correction and to include MSM estimations (under the assumption that MSM is a population hard to reach in a household survey), resulting in a total seroprevalence of 0.23% and an estimated number of people with HIV of 140,000.

[Knowledge about herpes simplex virus type 2 and human papillomavirus, and risk perception to acquire infections among college students]. / Conocimiento sobre el virus herpes simple tipo 2 y virus del papiloma humano, y percepción de riesgo a adquirir las infecciones entre estudiantes universitarios.

INTRODUCTION: herpes simplex virus type 2 (HSV-2) and human papillomavirus (HPV) are the most frequent sexually transmitted infections (STI) among college students 18-24 years old. Educational interventions for STI prevention can help to decrease viral STI prevalence among students. OBJECTIVE: to know the change in knowledge, perception of risk and sexual behavior among 182 students of the Autonomous University of the State of Morelos. MATERIAL AND METHOD: a community intervention trial (before-after) was carried out, using brochures for prevention of HSV-2 and HPV, including information about these STI, with emphasis on the risk factors identified in students of the same university. RESULTS: we found a change in the perception of STI risk during the intervention (56.5 before vs. 67.7% after intervention), possibly the brochures assisted students to learn more about their own risk behaviors. Likewise, there was an increase in knowledge in both HPV and HSV-2. CONCLUSIONS: it is necessary to increase the sample size in future interventions to assess further the change in knowledge, sexual behaviors and the prevalence of infections.

[Guideline for interpretation and report of the antibody to hepatitis C virus. Grupo de Desarrollo de la Guía ]. / Guía de interpretación y reporte del anticuerpo a hepatitis C.

Patients with hepatitis C virus (HCV) infection are detected by testing for the presence of antibodies to HCV (Anti-HCV). A positive Anti-HCV test represents a true positive result only in a variable proportion of subjects (35 to 95%). The qualitative interpretation as positive or negative Anti-HCV report is associated with a general lack of understanding regarding the interpretation of results, when more specific testing should be performed, and which tests should be considered for this purpose. Therefore, a substantial variation in supplemental testing practices exists among laboratories and physicians. This guideline was developed on the basis of the best available evidence to classify positive antibody in two (low and high) or three levels (very low, low and high) according to the signal to cutoff (S/CO) ratio: the very low level of the Anti-HCV identifies false-positive results and further diagnostic testing is not necessary. The low antibody level is frequently related with false-positive results and testing with Immunoblot is recommended; only Immunoblot-positive subjects require HCV RNA testing because of a low possibility of being viremic. The high Anti-HCV level is an accurate serological marker for predicting viremia and denotes the need of routine HCV RNA testing in order to efficiently confirm hepatitis C. Cost-effectiveness analysis, based on the Anti-HCV level, recommends the use of the two or three-levels to choose the confirmatory test of positive antibody. This approach can be implemented without increasing test costs because the S/CO ratio is automatically generated in most laboratory analyzers and would provide health care professionals with useful information for counseling and evaluating patients, to eliminate unwarranted notifications in cases of false antibody reactivity, and correctly identifying those Anti-HCV-positive patients who are infected and need antiviral treatment. The written report should include the antibody level (S/CO ratio), the type of the immunoassay applied and interpretation guideline. Anti-HCV testing is performed in multiple settings including blood banks or health department facilities; adoption of this Guideline for interpretation and report of the antibody to hepatitis C virus by laboratories and its implementation by clinicians will improve the accuracy for interpreting antibody result to determine the next step on hepatitis C diagnosis.

Heterogeneous distribution of hepatitis B serological markers in rural areas of Mexico.

OBJECTIVE: To study the distribution of the hepatitis B antibody (anti-HBc) based on a national serosurvey from 10 Mexican states showing a mean HBV prevalence higher than the national one. MATERIALS AND METHODS: This was a cross-sectional study. During 2003, anti-HBc was analyzed at INSP in 19 907 sera, and the related sociodemographic factors were determined. RESULTS: Anti-HBc prevalence was greater among men, but it was also associated to age, residence in a rural area, low socio-economic status, and illiteracy. Clusters of very high anti-HBc prevalence were found in several rural communities where the prevalence of anti-HBc in adults is 3 to 20 times the national average. CONCLUSIONS: Besides a low endemicity of HBV in Mexico, distribution is heterogeneous as was shown in several of the states studied, where there are rural towns with very high prevalence of HBV markers. National serosurveys are useful tools for identifying communities with hepatitis B hyperendemicity, where focused research and control measures are needed.

[Serological markers of hepatitis B and C, and HIV in La Calera and Cuambio, Guerrero, México]. / Marcadores serológicos de hepatitis B y C, y VIH en La Calera y Cuambio, Guerrero, México.

OBJECTIVE: To perform a hepatitis B, C, and HIV survey in an enhanced sample from two rural communities with the highest anti-HBc prevalence found in ENSA 2000. MATERIALS AND METHODS: This was a cross-sectional study.We studied the communities of La Calera and Cuambio, two adjacent rural towns of the district of Zirándaro, Guerrero, targeted because of the high prevalence of anti-HBc shown in ENSA 2000.We assessed the prevalence of hepatitis B and C, and HIV serological markers and associated factors among inhabitants older than 10 years. RESULTS: A very high prevalence of hepatitis B markers associated with socioeconomic factors was confirmed, while hepatitis C prevalence was low and HIV absent in the two communities addressed. CONCLUSIONS: National serosurveys are an accurate tool for identifying communities with hepatitis B high endemicity where focused research and control measures are needed.

Hepatitis C seroprevalence and correlation between viral load and viral genotype among primary care clients in Mexico.

OBJECTIVE: To measure hepatitis C virus (HCV) sero-prevalence, prevalence, hepatitis risk characteristics frequency, and genotype correlation with viral load among clients attending health care clinics. MATERIAL AND METHODS: Venous blood samples from l12 226 consecutive consenting adults were collected from January 2006 through December 2009. HCV antibodies were detected by immunoassay. HCV RNA was detected by qRT-PCR and viral genotype was performed by PCR and LIPA test. RESULTS: The HCV seroprevalence observed was l.5 % (C.I. 95% l.3-l.7), from seropositive individuals 60.9 % reported previous blood transfusion, 28.3% declared to have relatives with cirrhosis, 25.2% had tattoos or piercings, and 6.9% referred to have used drugs. Male gender and transfusion (p<0.001) were the most frequent hepatitis risk characteristics in the HCV seropositive group. Among seropositive subjects 48.3% presented HCV RNA.The most frequent genotype detected in all geographic areas of Mexico was l (subtype lA, 33%; subtype lB, 21.4%) followed by genotype 2 (subtype 2A, 8.50%). Subjects with genotype 1 had a significant correlation with the highest viral load. CONCLUSIONS: Our results show that nearly half of seropositive individuals are chronically infected. HCV infection has been shown in this study to be an emerging health problem in Mexico.

[Consensus on the clinical and microbiologic diagnosis of Bordetella pertussis, and infection prevention. Expert Group on Pertussis Vaccination]. / Consenso para el diagnóstico clínico y microbiológico y la prevención de la infección por Bordetella pertussis. Grupo de expertos en vacunación contra tos ferina.

Pertussis continues to be responsible for a significant disease burden worldwide. Although immunization practices have reduced the occurrence of the disease among children, waning vaccine- and infection-induced immunity still allows the disease to affect adolescents and adults who, in turn, can transmit the disease to non-immunized or partially immunized infants. This document is the result of a meeting in Mexico City of international experts who analyzed recent medical information in order to establish the current status of the epidemiology, diagnosis and surveillance of pertussis and, especially, the value of the dTpa booster dose in adolescents and adults as a pertussis prevention strategy in Mexico.

[Herpes simplex virus type 1: a possible sexually transmitted agent among college students]. / Virus del herpes simplex tipo 1: un posible agente de transmisión sexual en población universitaria.

OBJECTIVE: To study the factors associated with the presence of antibodies against herpes simplex virus type 1 (HSV-1) and to screen for HSV-1 in genital samples. MATERIALS AND METHODS: Students answered a survey and provided biological samples (blood and genital discharge). The detection of IgG and IgM antibodies against HSV-1 was performed by an ELISA test. From IgM positive samples we sought and extracted genital DNA and identified a beta-globulin gene and HSV-1. RESULTS: Eight hundred and fifteen students participated. IgG/HSV-1 seroprevalence was 56.7%, HSV-1 infection was associated with number of sexual partners, exchanging sex for money, same sex relationships and occasional partners. IgM/HSV-1 seroprevalence was 18.2%, 91 samples were positive for human beta-globuline but none for HSV-1 DNA. CONCLUSIONS: Epidemiological evidence suggests that HSV-1 could be transmitted by sexual contact among college students; however, HSV-1 was not detected in any of the genital samples analyzed. To further test our hypothesis we need to study HSV-1 among high risk groups or increase our sample size.

Herpes simplex virus type 2 among Mexican high school adolescents: prevalence and association with community characteristics.

BACKGROUND: We undertook this study to estimate the prevalence and correlates of herpes simplex virus type 2 (HSV-2) among Mexican adolescents in high school. METHODS: This was a cross-sectional analysis using data that had been collected to evaluate a school-based HIV prevention intervention. As part of the final round of evaluation, capillary blood samples were taken from volunteers to test for antibodies to HSV-2. The effect of each school's seroprevalence on the probability of an individual being seropositive was estimated, and the results were grouped by town to evaluate the association between characteristics of the locality and student HSV-2 seroprevalence. RESULTS: Dried blood spots were collected for 80% of the 1607 participants in the survey who reported that they were sexually active. Of these samples, 21% tested positive for HSV-2 antibodies, with no significant difference in prevalence between men and women. Seroprevalence among schools ranged from 0 to 57%. The number of sex workers registered in the locality was the most important covariate of seroprevalence, with each additional female sex worker (FSW) per 1000 women between 18 and 45 years of age in the town associated with an increase of 1% in the seroprevalence of HSV-2. CONCLUSIONS: Characteristics of adolescents' micro-environments that influence their pool of potential sexual partners and the likelihood that these partners are HSV-2 positive may be more important predictors of the risk of STI infection than self-reported condom use.

Molecular analysis of hepatitis B virus isolates in Mexico: predominant circulation of hepatitis B virus genotype H.

AIM: To determine the genotypes in Mexican hepatitis B virus (HBV) isolates and characterize their precore and core promoter mutations. METHODS: Forty-nine HBV isolates of Mexico obtained from sera of 15 hepatitis patients, 6 hemodialysis patients, 20 men seeking HIV testing, and 8 AIDS patients were analyzed. HBV isolates were amplified by PCR, and genotyped by line probe assay (INNO-LiPA HBV Genotyping; INNOGENETICS N V, Ghent, Belgium). HBV genotype confirmation was performed by DNA sequencing part of the sAg region. Precore and core promoter mutation characterization was performed by line probe assay (INNO-LiPA HBV PreCore; INNOGENETICS N V, Ghent, Belgium). RESULTS: Overall, HBV genotype H was found in 37 (75.5%) out of the 49 isolates studied. HBV genotypes G, A, and D were found in 5 (10.2%), 4 (8.2%), and 3 (6.1%) isolates, respectively. HBV genotype H was predominant in isolates from hemodialysis patients (100%), hepatitis patients (80%), and men seeking HIV testing (75%), and accounted for half of infections in AIDS patients (50%). Six (12.2%) out of the 49 HBV isolates showed both wild type and mutant populations at precore codon 28. These mixed wild type and precore mutant populations were observed in one HBV genotype A isolate and in all HBV genotype G isolates. A dual variant core promoter mutation was observed in 1 (2%) of the isolates, which was genotype H. CONCLUSION: HBV genotype H is highly predominant in HBV isolates of Mexico followed by genotypes G, A and D. A low frequency of precore and core promoter mutations is observed in HBV Mexican isolates.

[Maternal and congenital syphilis in two Mexican hospitals: evaluation of a rapid diagnostic test]. / Sífilis matema y congénita en dos hospitales mexicanos: evaluación de una prueba diagnóstica rápida.

OBJECTIVE: To estimate the prevalence of maternal and neonatal syphilis, to assess the usefulness of a rapid treponemic diagnostic test, and to evaluate the frequency of screening for syphilis during prenatal care in Mexican women. MATERIAL AND METHODS: This was a cross-sectional study that included 1,322 women interviewed in two hospitals (Hospital General in Cuernavaca, Morelos, and Hospital de la Mujer in Mexico City). Women answered a questionnaire on reproductive background, exposure to sexually transmitted infections and prenatal care. In order to diagnose syphilis, a rapid Determine TP test and a latex-VDRL test were used among all participating women. Positive cases were confirmed using FTA-ABS test. RESULTS: Prevalence of serologically active syphilis was 0.3% (4/1322). Using as comparison standard a combination of VDRL and FTA-ABS tests, the Determine TP test had a sensitivity and specificity of 100%. Two newborns with positive FTA-ABS IgM, one negative with FTA-ABS IgM and one first-trimester abortion were found from seropositive women. Prenatal serum screening for syphilis was conducted in only 6.9% of women included in the study. CONCLUSIONS: Although the prevalence of maternal syphilis is relatively low, results show that if the situation found in the hospitals studied is shared by other hospitals in Mexico, a systematic screening for maternal syphilis would help to diagnose more cases of this infection than the number reported in official figures. Screening of syphilis in pregnant women using rapid tests may help in the prevention of congenital syphilis.

[Ligase chain reaction testing of pooled urine specimens to diagnose Chlamydia trachomatis infection]. / Detección de Chlamydia trachomatis en orina por Lcr: aplicación del método de mezcla de muestras biológicas.

OBJECTIVE: The purpose of this study was to assess the utility and validity of pooling urine samples for molecular diagnosis of Chlamydia trachomatis infection. MATERIAL AND METHODS: Of 1,220 urine samples collected from Mexican female and male adolescents, 305 pools were composed of fourth individual samples each, based on a calculation of optimal pool size. These were processed by ligase chain reaction (LCR) for the detection of C. trachomatis. Positive and gray-zone pools were reanalyzed individually. Cost savings were calculated comparing actual costs of testing to the cost that would have been incurred testing all 1,220 samples individually. RESULTS: Pools results were: 56 positive, 19 gray-zones and 230 negative. Following individual retesting of positive and gray-zone pools, 59 cases of C. trachomatis infection were identified (4.8% prevalence). Thus, a total of 601 LCR tests were performed, for a 50.4% savings considering only the direct cost of the test. CONCLUSIONS: Our experience shows that sample pooling is both a reliable and convenient tool for CT surveillance in our setting. It should be considered in other similar settings where limited resources constraint surveillance of STIs.

[Consistency of HIV/AIDS transmission categories reported by the epidemiological surveillance of Chiapas State, Mexico: a problem of method]. / Consistencia de las categorías de transmisión sexual del VIH/SIDA informadas por el sistema de vigilancia epidemiológica del estado de Chiapas, México. Un problema metodológico.

OBJECTIVE: To compare the mechanisms of HIV/AIDS transmission reported by the epidemiological surveillance system information of the Chiapas State and those referred by HIV positive men interviewed in the Soconusco's region from the same state. METHODS: Databases containing information about the HIV/AIDS cases registered in the State of Chiapas and in the Soconusco's region were used. Additionally, 32 men previously detected as HIVpositive by the regional surveillance system answered a questionnaire about their sexual behavior and some socio-demographic characteristics. All participants provided a blood sample to identify antibodies against HIVusing two screening tests, ELISA and microagglutination, and one confirmatory test by Western blot. RESULTS: While the heterosexual transmission was predominant among HIV/AIDS cases reported by the epidemiological surveillance of Chiapas State and the Soconusco's (50.4% and 69. 40%, respectively), heterosexual transmission among the interviewed individuals was 36.7%. CONCLUSIONS: Contrary to the proposal about a process of "heterosexualization" of HIV/AIDS epidemic in Chiapas State and particularly in the Soconusco's region, the present study suggest that homosexual and bisexual behavior continue to be the main routes of HIV transmission among men. These results also suggest the presence of a methodological limitation in the evaluation of sexual behavior among HIV-seropositive individuals in the region. A gender analysis about masculinity, would allow a better understanding ofthe social and cultural aspects of sexuality that are not evident when only the sexual practices are evaluated.

Seroprevalence of hepatitis A virus in a cross-sectional study in Mexico: Implications for hepatitis A vaccination.

Hepatitis A virus (HAV) remains a public health concern worldwide contributing to significant morbidity in developed and developing countries. This cross-sectional database study estimated the overall HAV seroprevalence and the seroprevalence by gender, age, region and socioeconomic status in Mexico. Between January and October 2010, serum samples collected during the National Health and Nutrition survey (ENSANUT 2006) were obtained from subjects aged 1-95 y. Subjects' gender, age, geographical region and socioeconomic status were extracted from the survey and compiled into a subset database by the Mexican National Institute of Public Health. Anti-HAV antibodies were measured using a chemiluminescent immunoassay. A total of 3658 subjects were included in the according-to-protocol cohort. Overall, the HAV seroprevalence was 84.2%. The HAV seroprevalence rates were similar between females (86.1%) and males (82.2%). The percentage of subjects seropositive for anti-HAV antibodies was highest in adults aged ≥ 20 y (96.9%), followed by adolescents aged 10-19 y (80.1%) and lowest in children aged 1-9 y (45.0%) (p < 0.0001). Regionally, the highest HAV seroprevalence rate was observed in the South (88.8%) followed by Central and Northern Mexico and Mexico City (p = 0.02). The HAV seroprevalence was similar between subjects of high socioeconomic (90.1%) status and of low socioeconomic status (86.6%). This study confirms the intermediate HAV endemicity in Mexico. Cost-effectiveness studies are necessary to evaluate the inclusion of an effective hepatitis A vaccine from a population-based perspective in addition to continuous efforts to improve hygiene and sanitation that have a substantial impact on the disease burden.

Prevention and control of neoplasms associated with HPV in high-risk groups in Mexico City: The Condesa Study / Prevención y control de neoplasias asociadas a VPH en grupos de alto riesgo de la Ciudad de México: el Estudio Condesa

Abstract: Objective: To evaluate the effectiveness of a combined strategy of human papillomavirus virus (HPV) vaccination and high-risk HPV screening to reduce the occurrence of anogenital and oropharyngeal neoplasms among men who have sex with men, people with HIV, homeless people, transgender women, female sex workers and rape victims. Materials and methods: This mixed methods study evaluates the effectiveness of a combined vaccination-screening strategy to reduce HPV prevalence/incidence and occurrence of cervical intraepithelial neoplasms grade 2+ and/or anal intraepithelial neoplasms grade 2+, using Kaplan-Meier. The time-to-event method will evaluate time from positive results for specific anogenital HPV to incidence of anogenital lesions containing that HPV type. Results: People vaccinated against HPV and screened for HPV as a primary test will have lower prevalence and incidence of HPV infection and consequently lower frequency of HPV-related anogenital and oropharyngeal lesions. Conclusions: This study will generate scientific evidence on effectiveness of a combined vaccination-screening strategy to reduce the burden of HPV-associated neoplasms.

Resumen: Objetivo: Evaluar la efectividad de una estrategia combinada de vacunación contra el virus de papiloma humano (VPH) y tamizaje de VPH de alto riesgo para reducir neoplasias anogenitales y orofaringeas entre hombres que tienen sexo con hombres, personas con VIH, personas en situación de calle, mujeres transgénero, trabajadoras sexuales y víctimas de violación. Material y métodos: Este estudio evaluará la efectividad de una estrategia combinada de vacunación y tamizaje para reducir la ocurrencia de neoplasias intraepiteliales cervicales grado 2+ o neoplasias intraepiteliales anales grado NIA2+ utilizando Kaplan-Meier. Se evaluará tiempo de resultados positivos para tipos específicos de VPH anogenital a incidencia de lesiones anogenitales con ese tipo de VPH. Resultados: Las personas vacunadas contra VPH y con tamizaje de VPH tendrán menor prevalencia e incidencia de infecciones por VPH y por ende menor frecuencia de lesiones anogenitales y orofaringeas relacionadas con VPH. Conclusiones: Este estudio generará evidencia científica sobre la efectividad de una estrategia combinada de vacunación y tamizaje para reducir la carga de neoplasias asociadas al VPH.