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Objective This study aimed to estimate the risk of SARS-Cov2 infection and severe COVID-19 among healthcare workers from a major social security system. Methods This study actively followed a cohort of social security workers from March to December 2020 to determine the number of laboratory-confirmed symptomatic cases, asymptomatic associated contacts and COVID-19-associated hospitalizations and deaths. Workers were classified into those providing direct care to infected patients (COVID teams), other active healthcare workers (OAHCW), and workers under home protection (HPW). The number of cases and rates were also estimated by job category. Results Among a total of 542 381 workers, 41 461 were granted stay-at-home protection due to advanced age or comorbidities. Among the 500 920 total active workers, 85 477 and 283 884 were classified into COVID teams and OAHCW, respectively. Infection rates for COVID teams, OAHCW, and HPW were 20.1% [95% confidence interval (CI) 19.8–20.4], 13.7% (95% CI 15.0–15.3), and 12.2% (95% CI 11.8–12.5), respectively. The risk of hospitalization was higher among HPW. COVID teams had lower mortality rate per 10 000 workers compared to HPW (5.0, 95% CI 4.0–7.0 versus 18.1, 95% CI 14.0–23.0). Compared to administrative workers, ambulance personnel (RR 1.20; 95% CI 1.09–1.32), social workers (RR 1.16; 95% CI 1.08–1.24), patient transporters (RR 1.15; 95% CI 1.09–1.22) and nurses (RR 1.13; 95% CI 1.10–1.15) had a higher risk of infection after adjusting for age and gender. Crude differences in mortality rates were observed according to job category, which could be explained by differences in age, sex, and comorbidity distribution. Diabetes, obesity, hypertension, hemolytic anemia, and HIV were associated with increased fatality rates. Conclusions COVID team workers had higher infection rates compared to the total population of active workers and HPW. Doctors had lower risk of infection than respiratory therapists, nurses, and patient transporters, among whom interventions should be reconsidered to reduce risks. The presence of comorbidities, such as diabetes, obesity, arterial hypertension, hemolytic anemia, and HIV, increased the likelihood of complications caused by COVID-19, culminating in a poor prognosis.

Background Mexico has reported high death and case fatality rates due to COVID-19. Several comorbidities have been related to mortality in COVID-19, as hypertension, diabetes, coronary heart disease, chronic obstructive lung disease and chronic kidney disease. Aims To describe the main clinical characteristics of COVID-19 in the major social security institution in Mexico, as well as the contribution of chronic comorbidities and the population attributable fraction related to them. Methods Data for all patients with a positive test for SARS-CoV-2 in the institutional database was included for analysis. Demographic information, the presence of pneumonia and whether the patient was hospitalized or treated at home as an outpatient as well as comorbidities were analyzed. Case fatality rate was estimated for different groups. Odds ratios with 95% confidence intervals from a logistic regression model were estimated, as well as the population attributable fraction. Results By November 13, 2020, 323,671 subjects with COVID-19 infection have been identified. Case fatality rate is higher in males (20.2%), than in females (13.0%), and increases with age. Case fatality rate increased with the presence of obesity, hypertension and/or diabetes. Age and sex were major independent risk factors for mortality, as well as the presence of pneumonia, diabetes, hypertension, obesity, immunosuppression, and end-stage kidney disease. The population attributable fraction due to obesity in outpatients was 16.8%. Conclusions Major cardiovascular risk factors and other comorbidities increase the risk of dying in patients with COVID-19. Identification of populations with high fatality in COVID-19, provides insight to deal with this pandemic by health services in Mexico.

The objective was to know the behavior of fractures in Mexican children and adolescents. According to our study, fractures in Mexican male children and adolescents seem to be decreasing; however, we still need more national studies to know the possible causes of these fractures.To describe the trends of fractures in Mexican children and adolescents across a 12-year period (2007 to 2019), and to analyze if these trends have changed over time between sexes and age groups.We identified all fracture cases registered in children and adolescents (0 to 19 years) at the emergency rooms and surgical departments of the Mexican Institute of Social Security between January 2007 and December 2019. We used ICD-10 to classify the fractures. The population was divided into two age groups: children (0 to 9 years) and adolescents (10 to 19 years). Additional information regarding sex and age was gathered up as well. We calculated annual incidence; incidence rates are presented per 10,000 population at risk. Changes in fracture trends were calculated using the average annual percentage change (AAPC).Over 12 years, 1,400,443 fractures were registered. The most frequent site of fracture was forearm in 37.1% followed by shoulder (18.1%). The overall rates of fractures have remained similar over 12 years (86.5, IQR 81.0-94.2); however, a significant decrease in fractures was observed the last 3 years (2017-2019). According to the AAPC, only in men, in both age groups, a significant decrease in fractures was observed.This is the first study in Mexico to follow the behavior of fractures in the pediatric population over 12 years. Fractures seem to be decreasing in children and adolescents. An epidemiological follow-up of childhood fractures is necessary to understand the causes of fractures to generate better prevention and treatment strategies.

Background The study aimed to assess the performance of a multidisciplinary-team diabetes care program called DIABETIMSS on glycemic control of type 2 diabetes (T2D) patients, by using available observational patient data and machine-learning-based targeted learning methods. Methods We analyzed electronic health records and laboratory databases from the year 2012 to 2016 of T2D patients from six family medicine clinics (FMCs) delivering the DIABETIMSS program, and five FMCs providing routine care. All FMCs belong to the Mexican Institute of Social Security and are in Mexico City and the State of Mexico. The primary outcome was glycemic control. The study covariates included: patient sex, age, anthropometric data, history of glycemic control, diabetic complications and comorbidity. We measured the effects of DIABETIMSS program through 1) simple unadjusted mean differences; 2) adjusted via standard logistic regression and 3) adjusted via targeted machine learning. We treated the data as a serial cross-sectional study, conducted a standard principal components analysis to explore the distribution of covariates among clinics, and performed regression tree on data transformed to use the prediction model to identify patient sub-groups in whom the program was most successful. To explore the robustness of the machine learning approaches, we conducted a set of simulations and the sensitivity analysis with process-of-care indicators as possible confounders. Results The study included 78,894 T2D patients, from which 37,767patients received care through DIABETIMSS. The impact of DIABETIMSS ranged, among clinics, from 2 to 8% improvement in glycemic control, with an overall (pooled) estimate of 5% improvement. T2D patients with fewer complications have more significant benefit from DIABETIMSS than those with more complications. At the FMC’s delivering the conventional model the predicted impacts were like what was observed empirically in the DIABETIMSS clinics. The sensitivity analysis did not change the overall estimate average across clinics. Conclusions DIABETIMSS program had a small, but significant increase in glycemic control. The use of machine learning methods yields both population-level effects and pinpoints the sub-groups of patients the program benefits the most. These methods exploit the potential of routine observational patient data within complex healthcare systems to inform decision-makers.

Background The Mexican health system segments access and right to healthcare according to worker position in the labour market. In this contribution we analyse how access and continuity of healthcare gets interrupted by employment turnover in the labour market, including its formal and informal sectors, as experienced by affiliates to the Mexican Institute of Social Security (IMSS) at national level, and of workers with type 2 diabetes (T2DM) in Mexico City. Methods Using data from the National Employment and Occupation Survey, 2014, and from IMSS electronic medical records for workers in Mexico City, we estimated annual employment turnover rates to measure the loss of healthcare access due to labour market dynamics. We fitted a binary logistic regression model to analyse the association between sociodemographic variables and employment turnover. Lastly we analysed job-related access to health care in relation to employment turnover events. Results At national level, 38.3% of IMSS affiliates experienced employment turnover at least once, thus losing the right to access to healthcare. The turnover rate for T2DM patients was 22.5%. Employment turnover was more frequent at ages 20–39 (38.6% national level; 28% T2DM) and among the elderly (62.4% national level; 26% T2DM). At the national level, higher educational levels (upper-middle, OR = 0.761; upper, OR = 0.835) and income (5 minimum wages or more, OR = 0.726) were associated with lower turnover. Being single and younger were associated with higher turnover (OR = 1.413). T2DM patients aged 40–59 (OR = 0.655) and with 5 minimum wages or more (OR = 0.401) experienced less turnover. Being a T2DM male patient increased the risk of experiencing turnover (OR = 1.166). Up to 89% of workers losing IMSS affiliation and moving on to other jobs failed to gain job-related access to health services. Only 9% gained access to the federal workers social security institute (ISSSTE). Conclusions Turnover across labour market sectors is frequently experienced by the workforce in Mexico, worsening among the elderly and the young, and affecting patients with chronic diseases. This situation needs to be prospectively addressed by health system policies that aim to expand the financial health protection during an employment turnover event.

To describe the annual incidence of type 1 diabetes in children and adolescents insured by the Mexican Institute of Social Security, the main health provider in Mexico, during 2000-2018.We conducted a secondary data analyses using the incidence registers from the Epidemiological Surveillance Coordination of the Mexican Institute of Social Security collected during 2000-2018. Incident type 1 diabetes cases (age 19 years old and below) were identified using ICD-10-CM E10 diagnostic codes. Age, sex, and geographical region and seasonal-specific incidence were calculated with their corresponding annual percentage change (APC) as well.In the period 2000-2018, the number of incident cases with type 1 diabetes decreased from 3.4 to 2.8 per 100,000 in insured for subjects below 20 years old. We observed an increase in the 2000-2006, followed by a decrease for the 2006-2018 period (APC +16.1 and -8.7 respectively). Females and children5 years old had a significant decrease in the incidence rate, while inhabitants in Central Mexico showed a significant increase. No difference was found in incidence between seasons.Our study describes significant fluctuations of the incidence of type 1 diabetes during the period 2000-2018, which appeared to correspond to influenza outbreaks, among Mexican children and adolescents.

Natural disasters cause mental disorders, the most frequent are Post-traumatic stress disorder (PTSD) and depression, which should be quickly identified for immediate psychological care. The aim of this study was to estimate the frequency of these disturbances in a population with social security, located in the states hit by the earthquake that took place on September 19To identify persons with PTSD and depression, a random sample of the population was screened (1-2 months' post-earthquake) in primary health care clinics at the Mexican Institute of Social Security (IMSS). A questionnaire for the detection of mental conditions (The Screening Questionnaire for Disaster Mental Health, SQD) was used to select people for group therapy and/or psychotherapeutic support, when identified with severe PTSD and high risk of depression.Over 44,855 persons (67.9% females, 32.1% males), residents of Mexico City, the State of Mexico, Puebla, Morelos were surveyed. The prevalence of severe PTSD was 11.9% and depression 9.2%. The highest prevalence of PTSD was observed in Mexico City (12.8%) the state with more material damage. Women were at higher risk for PTSD (OR, 2.08; 95% CI 1.97-2.19, p = 0.000) and depression (OR, 1.86; 95% CI 1.72-2.01, p = 0.000).The prevalence of PTSD and depression was higher in those states with severe damage caused by the earthquake; women were more susceptible to mental disorders.

espanolIntroduccion: La prevalencia de complicaciones cronicas y comorbilidades en pacientes con diabetes tipo 2 (DT2) se han incrementado en el mundo. Objetivo: Comparar la prevalencia de complicaciones y comorbilidades cronicas en pacientes con DT2 en 36 unidades de medicina familiar de cinco delegaciones del Instituto Mexicano del Seguro Social (IMSS). Metodos: Conforme los codigos de la Decima Revision de la Clasificacion Internacional de Enfermedades se identificaron las complicaciones (hipoglucemia, pie diabetico, enfermedad renal, retinopatia, enfermedad cardiaca isquemica, enfermedad cerebrovascular y falla cardiaca) y comorbilidades (enfermedad hepatica, cancer, anemia) de DT2. Se compararon por delegacion, edad, sexo y tiempo de evolucion. Resultados: Las complicaciones y comorbilidades fueron mas comunes en personas ≥ 62 anos. De 297 100 pacientes, 34.9 % presento cualquier complicacion; microvasculares en el norte industrial (32 %), macrovasculares en el este rural (12.3 %) y comorbilidades (5 %) en el sur de la Ciudad de Mexico; estas complicaciones predominaron en los hombres (cualquier complicacion 30.2 %). La falla cardiaca y las comorbilidades fueron mas comunes en mujeres (5.6 y 4.9 %). Conclusiones: Las complicaciones y comorbilidades de DT2 mostraron diferencias geograficas y de sexo y fueron mayores con la edad y el tiempo de evolucion. Urge reforzar estrategias para la prevencion de las complicaciones y comorbilidades en los pacientes con DT2. EnglishIntroduction: The prevalence of chronic complications and comorbidities in patients with type 2 diabetes (T2D) has increased worldwide. Objective: To compare the prevalence of complications and chronic comorbidities in patients with T2D at 36 family medicine units of five chapters of the Mexican Institute of Social Security (IMSS). Method: Complications (hypoglycemia, diabetic foot, kidney disease, retinopathy, ischemic heart disease, cerebrovascular disease and heart failure) and comorbidities (liver disease, cancer and anemia) were identified according to codes of the International Classification of Diseases, 10th Revision. Comparisons were made by chapter, age, gender and evolution time. Results: Complications and comorbidities were more common in subjects aged ≥ 62 years. Out of 297 100 patients, 34.9 % had any complication; microvascular complications (32 %) prevailed in the industrial North, whereas macrovascular complications (12.3 %) did in the rural East, and comorbidities (5 %) in southern Mexico City. Complications predominated in men (any complication, 30.2 %). Heart failure and comorbidities were more common in women (5.6 % and 4.9 %, respectively). Conclusions: T2D complications and comorbidities showed geographic and gender differences, and were greater with older age and longer evolution time. It is urgent for strategies for the prevention of complications and comorbidities to be reinforced in patients with T2D.

Introduction At the end of 2015, the first cases of Zika were identified in southern Mexico. During 2016, Zika spread as an outbreak to a large part of the country's coastal zones. Methodology The Zika epidemiological surveillance system records cases with clinical symptoms of Zika virus disease (ZVD) and those confirmed by means of a reverse polymerase chain reaction (RT-PCR) assay. This report includes the suspected and confirmed cases from 2016. Incidence rates were estimated by region and in pregnant women based on the proportion of confirmed cases. Results In total, 43,725 suspected cases of ZVD were reported. The overall incidence of suspected cases of ZVD was 82.0 per 100,000 individuals and 25.3 per 100,000 Zika cases. There were 4,168 pregnant women with suspected symptoms of ZVD, of which infection was confirmed in 1,082 (26%). The estimated incidence rate of ZVD for pregnant women nationwide was 186.1 positive Zika cases per 100,000 pregnant women. Conclusions The incidence of Zika in Mexico is higher than that reported previously in the National System of Epidemiological Surveillance. Positive cases of Zika must be estimated and reported.

Background Zika, dengue and chikungunya viruses (ZIKV, CHIKV and DENV) are temporally associated with neurological diseases, such as Guillain-Barré syndrome (GBS). Because these three arboviruses coexist in Mexico, the frequency and severity of GBS could theoretically increase. This study aims to determine the association between these arboviruses and GBS in a Mexican population and to establish the clinical characteristics of the patients, including the severity of the infection. A case-control study was conducted (2016/07/01-2018/06/30) in Instituto Mexicano del Seguro Social (Mexican Social Security Institute) hospitals, using serum and urine samples that were collected to determine exposure to ZIKV, DENV, CHIKV by RT-qPCR and serology (IgM). For the categorical variables analysis, Pearson’s χ2 or Fisher exact tests were used, and the Mann-Whitney U test for continuous variables. To determine the association of GBS and viral infection diagnosis through laboratory and symptomatology before admission, we calculated the odds ratio (OR) and 95% confidence intervals (95%CI) using a 2x2 contingency table. A p-value ≤ 0.05 was considered as significant. Ninety-seven GBS cases and 184 controls were included. The association of GBS with ZIKV acute infection (OR, 8.04; 95% CI, 0.89–73.01, p = 0.047), as well as laboratory evidence of ZIKV infection (OR, 16.45; 95% CI, 2.03–133.56; p = 0.001) or Flavivirus (ZIKV and DENV) infection (OR, 6.35; 95% CI, 1.99–20.28; p = 0.001) was observed. Cases of GBS associated with ZIKV demonstrated a greater impairment of functional status and a higher percentage of mechanical ventilation. According to laboratory results, an association between ZIKV or ZIKV and DENV infection in patients with GBS was found. Cases of GBS associated with ZIKV exhibited a more severe clinical picture. Cases with co-infection were not found., Author summary Dengue (DENV), chikungunya (CHIKV), and Zika (ZIKV) are considered as emerging or re-emerging viruses. Recently, these viruses have produced major epidemics in tropical climate urban centers, and have been associated with neurological manifestations, including Guillain-Barre syndrome (GBS), which causes muscle weakness, unstable gait, and decreased or absent musculoskeletal reflexes. This study aims to investigate the association between these viral infections and GBS. A case and control study was conducted nationwide, including 97 cases of GBS and 184 controls matched by age, gender, and locality, but not the disease. The study shows a positive association between GBS cases and ZIKV or ZIKV and DENV infection. GBS cases associated with ZIKV depicted a more severe clinical picture (more impairment of functional status, incapacity, and a higher percentage of mechanical ventilation). Finally, the symptoms of suspected ZIKV disease prior to the development of GBS were similar to some previous reports. The impact of the interaction of these three arboviruses, particularly ZIKV, on the health of the Mexican population was less than expected. The Mexican experience could be useful for other populations.

Background. P rimary health care is the best framework for implementing actions for the prevention and control of non-communicable diseases at an appropriate scale. In 2002, the Mexican Institute for Social Security (IMSS), which provides health care to half of the Mexican population, implemented a primary care-based integrated program that included the improvement of the family health care practice and a preventive strategy called PREVENIMSS, to reduce the burden of disease. Objective. T o asess the impact of this program on selected non-communicable chronic diseases. Methods. Morbidity and mor tality were compared before and after implementation of the program and time trends in IMSS affiliates and non-affiliates using the difference-in-differences (DD) method. Results. Incidence rates of diabetes and h ypertension increased whereas those of cervical cancer, breast cancer and other cerebrovascular diseases decreased from 2000 to 2013. The DD in mortality rates, expressed per 100 0 00 persons, showed a decrease of 49.4 for diabetes mellitus, 9.1 for hypertensive disease, 42.9 for ischemic heart disease, 17.4 for cerebrovascular disease, 7.5 for cervical cancer and 5.8 for breast cancer. Conclusions. The reductions in mortality rates could be explained by both changes in incidence rates and changes in case fatality rates associated with early detection and treatment. These initial findings can be interpreted as the potential impact of integrated programs based on primary health care in a developing country.

Objectives The Mexican Institute of Social Security (IMSS) provides a package of health, economic and social benefits to workers employed in private firms within the formal labour market and to their economic dependants. Affiliates have a right to these benefits only while they remain contracted, thus posing a risk for the continuity of healthcare. This study evaluates the association between the time (in days) without the right to healthcare due to job loss in the formal labour market and the quality of healthcare and clinical outcomes among IMSS affiliates with Type 2 diabetes mellitus (T2DM). Design Retrospective cohort study 2013-2015. Setting Six IMSS family medicine clinics (FMC) in Mexico City. Participants T2DM patients (n = 27 217) affiliated with job-related health insurance and at least one consultation with a family doctor during 2013. Source of Information IMSS affiliation department database and electronic health records and clinical laboratory databases. Main Outcome Measure(s) Quality of the processes (eight indicators) and outcomes (three indicators) of healthcare. Results The results indicated that losing IMSS right to healthcare is frequent, occurring to one-third of T2DM patients during the follow-up period. The time without the right to healthcare in the observed period was of 120 days on average and was associated with a 43.2% loss of quality of care and a 19.2% reduction in clinical outcomes of T2DM. Conclusion Policies aimed at ensuring access and continuity of care, regardless of job status, are critical for improving the quality of processes and outcomes of healthcare for diabetic patients.

To evaluate auditory function in a group of workers exposed to organic solvent mixture at a paint factory.Cross-sectional study.One hundred and sixty-one workers were studied, 77 exposed to solvents and 84 unexposed. Fourteen solvents were measured, including toluene, xylene, and n-hexane. Pure-tone audiometry and brainstem auditory-evoked potentials (BAEP) were performed. Industrial noise was85 dBA and exposure levels to organic solvents were low.The exposed group showed a hearing impairment in both ears compared with the unexposed workers. Multiple linear regression models adjusted by age, chronic pathologies, and environmental noise for frequency means between 125 and 8000 Hz produced the following results: for the left ear, R(2) = 33.3%, exposed vs. unexposed β = 4.1 (p0.001); and for the right ear, R(2) = 38%, exposed vs. unexposed β = 4.8 (p0.001). Adjusted for age and chronic pathologies, waves III and V, and interpeak interval latencies were increased (p0.05) in both ears in the exposed group.Although solvent mixture concentrations and noise levels were low, our results demonstrate that there may be a concurrent ototoxicity and neurotoxicity condition and emphasize the importance of including BAEP analysis for comprehensive assessments. Future studies that include otoacoustic emissions assessments to monitor cochlear function and central auditory processing tests are imperative.

The lower extremity amputations diminish the quality of life of patients with Diabetes Mellitus (DM). The aim of this study was to describe the lower extremity amputation rates in subjects with DM in the Mexican Social Security Institute (IMSS), comparing 2004 and 2013.A comparative cross-sectional study was done. Amputations were identified from the hospital records of System of Medical Statistics (DataMart). The DM patient census was obtained from the System of Integral Attention to Health. Major and minor amputations rates were expressed per 100,000 DM patients.We observed 2 334 340 and 3 416 643 DM patients during 2004 and 2013, respectively. The average age at the time of the amputation was similar in 2004 and 2013 (61.7 and 65.6 years old for minor and major amputations respectively). The major amputations rates were 100.9 and 111.1 per 100 000 subjects with DM in during 2004 and 2013 (p = 0.001); while minor amputations rates were 168.8 and 162.5 per 100 000 subjects with DM in during 2004 and 2013 respectively (p = 0.069).The lower extremity amputations rates at IMSS are very high compared with that reported in developed countries. The major amputations rate increased in 2013 compared with 2004.Introducción: las amputaciones de extremidades inferiores disminuyen la calidad de vida de los pacientes con diabetes mellitus (DM). El objetivo de este estudio fue describir el índice de amputaciones de extremidades inferiores (mayores y menores) en sujetos con DM adscritos al Instituto Mexicano del Seguro Social (IMSS), comparando los años 2004 y 2013. Métodos: estudio observacional transversal comparativo. Se evaluaron los registros hospitalarios de amputaciones obtenidos del Sistema de Estadísticas Médicas (DataMart) y del Censo de pacientes con DM obtenido del Sistema de Atención Integral a la Salud. Se calcularon los índices de amputaciones mayores y menores x 100,000 sujetos con DM adscritos a Medicina Familiar. Resultados: durante 2004 y 2013 se observaron 2 334 340 y 3 416 643 pacientes con DM adscritos a Medicina Familiar respectivamente. Los promedios de edad al momento de la amputación fueron similares en el año 2004 y 2013 (61.7 años para las amputaciones menores y 65.6 años para las amputaciones mayores). Los índices de amputaciones mayores fueron de 100.9 y de 111.1 x 100 000 sujetos con DM en 2004 y 2013; mientras que el índice de amputaciones menores de extremidades inferiores fue de 168.8 y de 162.5 x 100 000 sujetos con DM en el durante 2004 y 2013 respectivamente. Conclusiones: el índice de amputaciones de extremidades inferiores en el IMSS es muy alto comparado con lo reportado en países desarrollados. El índice de amputaciones mayores se incrementó para el año 2013, comparado con 2004.

A substantial recrudescent wave of pandemic influenza A/H1N1 affected the Mexican population from December 1, 2011-March 20, 2012 following a 2-year period of sporadic transmission.We analyzed demographic and geographic data on all hospitalizations with severe acute respiratory infection (SARI) and laboratory-confirmed A/H1N1 influenza, and inpatient deaths, from a large prospective surveillance system maintained by a Mexican social security medical system during April 1, 2009-March 20, 2012. We also estimated the reproduction number (R) based on the growth rate of the daily case incidence by date of symptoms onset.A total of 7569 SARI hospitalizations and 443 in-patient deaths (5.9%) were reported between December 1, 2011, and March 20, 2012 (1115 A/H1N1-positive inpatients and 154 A/H1N1-positive deaths). The proportion of laboratory-confirmed A/H1N1 hospitalizations and deaths was higher among subjects ≥60 years of age (χ(2) test, p0.0001) and lower among younger age groups (χ(2) test, p0.04) for the 2011-2012 pandemic wave compared to the earlier waves in 2009. The reproduction number of the winter 2011-2012 wave in central Mexico was estimated at 1.2-1.3, similar to that reported for the fall 2009 wave, but lower than that of spring 2009.We documented a substantial increase in the number of SARI hospitalizations during the period December 2011-March 2012 and an older age distribution of laboratory-confirmed A/H1N1 influenza hospitalizations and deaths relative to 2009 A/H1N1 pandemic patterns. The gradual change in the age distribution of A/H1N1 infections in the post-pandemic period is consistent with a build-up of immunity among younger populations.

Background and Aims Occupational exposure to low-level benzene and the joint action of toluene–xylene probably cause effects on circulating monocytes immune response. We undertook this study to determine relationship between occupational exposure to benzene–toluene–xylene mixture (BTX) and IL-10, TNF and IL-12 production by peripheral blood mononuclear cells. Methods Exposure was estimated in 54 workers from a paint company in Mexico City through BTX accumulated potential dose (BTX-APD). Two exposure groups were formed: high and low BTX-APD established with a cutoff point at ≥1.0 of BTX-APD, as a function of the geometric mean of the estimator's value distribution and the higher agreement between BTX-APD ≥1.0 and the areas referred as using (or not) organic solvents in the work process. IL-10, TNF and IL-12 concentrations were measured with ELISA. Through multiple linear regression models, the production of each of the proposed cytokines and of the whole set was assessed. Results Workers with high BTX-APD showed a significant reduction in TNF production (β = −1,196.0 pg/mL; p = 0.01); a reduction for IL-10 (β = −520.3; p = 0.13) and IL-12 (β = −843.3; p = 0.09) was also observed, although without statistical significance. Conclusions TNF production assessed in workers with a high BTX-APD is lower than in those with a low BTX-APD, but not in IL-10 and IL-12 production.

Several studies have suggested that human semen quality has declined over the past decades and some of them have associated it with occupational exposure to pesticides. However, most of these studies have not been associated with a reliable exposure level and have been designed mostly as cross-sectional studies. The present work evaluates, in a longitudinal follow-up study, the effect of organophosphate pesticides (OP) at three occupational exposure levels on semen quality. In addition, the study examined the association between OP urinary levels and sperm parameters in exposed and unexposed workers. A total of 139 semen samples from 52 volunteers were assessed. Urinary OP levels were measured by gas-liquid chromatography. The results revealed that the poorest semen quality was found among the subjects with the highest OP exposure and the highest urinary OP levels. Seasonal variations in sperm concentration and sperm count were registered. The results showed a significant decrease in total sperm count among subjects with the highest exposure to OP. Further studies assessing the effects of OP on male reproductive health should be controlled by the variability in human sperm parameters, sperm seasonality, spermatogenesis time and the changing OP exposure level in men highly exposed to OP.

Pesticide exposure, including organophosphorous (OP) insecticides, has been associated with poor semen quality, and paraoxonase (PON1), an enzyme involved in OP deactivation, may have a role on their susceptibility, due to PON1 polymorphisms. Our objective was to evaluate the role of PON1Q192R polymorphism on the susceptibility to OP toxicity on semen quality and DNA integrity in agricultural workers. A cross-sectional study was conducted in farmers with Mayan ascendancy from southeastern Mexico chronically exposed to pesticides; mostly OP. Fifty four agricultural workers (18-55 years old) were included, who provided semen and blood samples. Semen quality was evaluated according to WHO, sperm DNA damage by in situ-nick translation (NT-positive cells), PON1Q192R polymorphism by real-time PCR and serum PON1 activity by using phenylacetate and paraoxon. Two OP exposure indexes were created: at the month of sampling and during 3 months before sampling, representing the exposure to spermatids-spermatozoa and to cells at one spermatogenic cycle, respectively. PON1 192R and 192Q allele frequencies were 0.54 and 0.46, respectively. Significant associations were found between OP exposure at the month of sampling and NT-positive cells and sperm viability in homozygote 192RR subjects, and dose-effect relationships were observed between OP exposure during 3 months before sampling and sperm quality parameters and NT-positive cells in homozygote 192RR farmers. This suggests that cells at all stages of spermatogenesis are target of OP, and that there exists an interaction between OP exposure and PON1Q192R polymorphism on these effects; farmers featuring the 192RR genotype were more susceptible to develop reproductive toxic effects by OP exposure.

Objective The aim was to identify exposure levels to dichlorodiphenyltrichloroethane (DDT) and to assess maternal factors as determinants of the serum dichlorodiphenyldichloroethylene (DDE) concentration in umbilical cord in newborns from the Mexican Pacific coastal area of Oaxaca State. Materials and Methods A cross-sectional study was conducted of 86 paired mothers and newborns from the Oaxaca community of Pochutla. Blood and umbilical cord blood samples were collected to determine DDT and DDE by GC. Information concerning possible determinant factors with regard to pesticide concentration was obtained by means of a questionnaire. Results A positive correlation between maternal and umbilical cord serum DDE concentration was observed (geometric mean of 7.69 µg g−1 and 7.29, respectively). Multiple analyses showed that significant maternal factors related to umbilical cord serum DDE concentrations were: always having lived in the same community; low to high socioeconomic strata; accumulated breast-feeding time. Conclusions The determinant factors observed in this study must be considered in future studies for the quantification of organochlorine concentration. In addition, these factors must be taken into account when preventive actions to minimize in utero exposure to these pesticides are carried out. Copyright © 2007 John Wiley & Sons, Ltd.

Objective. To estimate the disease burden of cancer in the affiliate population of the Mexican Social Security Institute (Instituto Mexicano del Seguro Social, IMSS) in 2010 by delegation. Materials and methods. The Disability-Adjusted Life Years (DALYs), Years of Life Lost (YLL) due to premature mortality and Years Lived with Disability/Disease (YLD) for 21 specific cancers and a subgroup of other malignant neoplasms were calculated based on the methodology of the Global Burden of Disease Study (GBD) for each of the 35 delegations of the IMSS. Results. In 2010, cancer represented the fifth overall leading cause of disease burden in IMSS affiliates (16.72 DALYs/1000 affiliates). A total of 75% of the cancer disease burden in each delegation is due to ten specific cancers, particularly breast cancer, which ranks first in 82% of the delegations. Prostate cancer; tracheal, bronchial, and lung cancers; leukemia, and colorectal and stomach cancers occupy the second to fourth positions in each delegation. With the exception of breast and prostate cancer, for which the contribution of YLD to the DALYs was higher than 50%, the greatest contribution to the DALYs of the other cancers was premature mortality, which accounted for more than 90% of the DALYs in some cases. Conclusion. The results obtained in this study allow for the identification of intervention priorities with regard to cancer at the institutional level and also for the focus at the delegation level to be placed on cancers ranking in the top positions for disease burden.

Objective. To analyze cancer mortality in affiliates of the Mexican Social Security Institute (Instituto Mexicano del Seguro Social -IMSS) and time trends in the risk of death due to cancer from 1989 to 2013. Materials and methods. A descriptive analysis of cancer mortality trends in beneficiaries of the IMSS was performed. Age and sex adjusted mortality rates were obtained using direct standardization with the WHO population. Changes in the risk of death due to cancer over time were evaluated using Poisson regression. Results. The absolute number of deaths due to cancer doubled from 1989 to 2013 due to increasing age of the affiliate population. The risk of death among affiliates decreased for the majority of cancers except for colon and rectal cancer. Conclusion. The risk of dying from cancer among IMSS affiliates showed a marked decrease, which may be due to an increase in detection and opportune treatment. DOI: http://dx.doi.org/10.21149/spm.v58i2.7784

Urban centers in Latin American often face high levels of air pollution as a result of economic and industrial growth. Decisions with regard to industry, transportation, and development will affect air pollution and health both in the short term and in the far future through climate change. We investigated the pollution health consequences of modest changes in fossil fuel use for three case study cities in Latin American: Mexico City, Mexico; Santiago, Chile; and Sao Paulo, Brazil. Annual levels of ozone and particulate matter were estimated from 2000 to 2020 for two emissions scenarios: (1) business-as-usual based on current emissions patterns and regulatory trends and (2) a control policy aimed at lowering air pollution emissions. The resulting air pollution levels were linked to health endpoints through concentration–response functions derived from epidemiological studies, using local studies where available. Results indicate that the air pollution control policy would have vast health benefits for each of the three cities, averting numerous adverse health outcomes including over 156,000 deaths, 4 million asthma attacks, 300,000 children's medical visits, and almost 48,000 cases of chronic bronchitis in the three cities over the 20-year period. The economic value of the avoided health impacts is roughly $21 to $165 billion (US). Sensitivity analysis shows that the control policy yields significant health and economic benefits even with relaxed assumptions with regard to population growth, pollutant concentrations for the control policy, concentration–response functions, and economic value of health outcomes. This research demonstrates the health and economic burden from air pollution in Latin American urban centers and the magnitude of health benefits from control policies.

Particulate air pollution has been related with cardiopulmonary morbidity and mortality. Recent studies have shown that an increase in particulate matter (PM)(2.5) ambient concentrations was associated with a decrease in heart rate variability (HRV) in the elderly with cardiovascular conditions, which could increase the risk of death. In order to assess if this association could also be observed in young adults, we studied 40 young healthy residents of the Mexico City Metropolitan Area (MCMA) who underwent 13 h Holter electrocardiographic and PM(2.5) personal monitoring. HRV was evaluated in time domain: the standard deviation of normal RR intervals (SDNN) and the percentage of differences between adjacent normal RR intervals larger than 50 ms (pNN50). In multivariate analysis with mixed effects models, a significant negative association of pNN50 with PM(2.5) accumulative exposure was found. An increase in 30 microg/m(3) of the average PM(2.5) personal exposure in the previous 2 h decreased the pNN50 in 0.08% (P=0.01). This observation revealed an acute effect related to environmental exposure to PM(2.5) with regard to HRV in normal youngsters. The long-term health consequences of this association in young healthy adults remain to be clarified.

Organophosphorous pesticides (OPs) are suspected of altering reproductive function by reducing brain acetylcholinesterase activity and monoamine levels, thus impairing hypothalamic and/or pituitary endocrine functions and gonadal processes. Our objective was to evaluate in a longitudinal study the association between OP exposure and serum levels of pituitary and sex hormones. Urinary OP metabolite levels were measured by gas–liquid chromatography, and serum pituitary and sex hormone levels by enzymatic immunoassay and radioimmunoassay in 64 men. A total of 147 urine and blood samples were analyzed for each parameter. More than 80% of the participants had at least one OP metabolite in their urine samples. The most frequent metabolite found was diethylthiophosphate (DETP; 55%), followed by diethylphosphate (DEP; 46%), dimethylthiophosphate (DMTP; 32%), and dimethyldithiophosphate (DMDTP; 31%). However, the metabolites detected at higher concentrations were DMTP, DEP, DMDTP, and dimethylphosphate. There was a high proportion of individuals with follicle-stimulating hormone (FSH) concentrations outside the range of normality (48%). The average FSH serum levels were higher during the heavy pesticide spraying season. However, a multivariate analysis of data collected in all periods showed that serum FSH levels were negatively associated with urinary concentrations of both DMTP and DMDTP, whereas luteinizing hormone (LH) was negatively associated with DMTP. We observed no significant associations between estradiol or testosterone serum levels with OP metabolites. The hormonal disruption in agricultural workers presented here, together with results from experimental animal studies, suggests that OP exposure disrupts the hypothalamic–pituitary endocrine function and also indicates that FSH and LH are the hormones most affected.

Arsenic is a ubiquitous element found in several forms in foods and environmental media such as soil, air, and water; the predominant form in drinking water is inorganic As (iAs), which is both highly toxic and readily bioavailable. iAs is a recognized carcinogen in humans [National Research Council (NRC) 2001]. Chronic ingestion of iAs-contaminated drinking water is therefore considered the major pathway behind the risk to human health. It has been estimated that 200 million people worldwide are at risk from health effects associated with high concentrations of As in their drinking water (NRC 2001). Several other regions in the world are exposed to levels above the maximum permissible limit recommended by the World Health Organization (WHO 1993). In humans, the chronic ingestion of iAs (> 500 μg/day As) has been associated with cardiovascular, nervous, hepatic, and renal alterations and diabetes mellitus as well as cancer of the skin, bladder, lung, liver, and prostate [Agency for Toxic Substances and Disease Registry (ATSDR) 2000]. Characteristic features of arseniasis include skin manifestations, such as hyperpigmentation, hypopigmentation, and hyperkeratosis on the palms and soles, and skin cancer at later stages (Cebrian et al. 1983; Schwartz 1997; Tseng et al. 1968). In humans, the mechanism by which iAs exerts its toxic effects is very complex because its metabolism involves at least five metabolites that can exert toxic effects. The scheme for the stepwise conversion of arsenite (iAsIII) into mono-, di-, and trimethylated products is as follows: Briefly, the metabolic process is carried out in two processes: a) the reactions of reduction that convert the pentavalent species to trivalency, and b) reactions of oxidative methylations where iAs is converted to mono-, di-, and trimethyl arsenic forms (MAs, DMAs, and TMAsO, respectively). Thus, both pentavalent methylarsenic (MAsV) and trivalent methylarsenic (MAsIII) forms are intermediates or products of this pathway (Lin et al. 2002; Thomas et al. 2004). Using S-adenosylmethionine as a methyl group donor, As methyltransferase (Cyt19, EC 2.1.1.138) has been shown to catalyze reactions, reduction and oxidative methylation, in rodents and humans (Waters et al. 2004). Other studies have shown the capacity of two mammalian proteins to reduce iAsV, glutathione S-transferase omega (GST Ω, EC 2.5.1.18) (Zakharyan et al. 2001) and the purine nucleoside phosphorylase (PNP, EC 2.4.2.1) (Nemeti et al. 2003; Radabaugh et al. 2002). Urinary As is generally regarded as the most reliable indicator of recent exposure to iAs and is used as the main biomarker of exposure (Mushak and Crocetti 1995). In addition, the urinary profiles of iAs metabolites have frequently been used in epidemiologic studies to assess the capacity of exposed individuals to methylate iAs. During almost 20 years, the methylation of iAs has been generally evaluated using urinary measurement of iAs (III + V), MAs (III + V), and DMAs (III + V) in people exposed to As. Nevertheless, the differentiation of the trivalent intermediaries of As metabolism is important because the trivalent methylated arsenicals, MAsIII and DMAsIII, are more potent than either iAsIII or iAsV in cytotoxicity (Styblo et al. 2000), genotoxicity (Mass et al. 2001; Nesnow et al. 2002), and inhibition of enzymes with antioxidative functions (Lin et al. 2001; Styblo et al. 1997). Therefore, the formation of MAsIII and DMAsIII in the methylation pathway for iAs may play a significant role in the induction of toxic effects associated with exposures to iAs. The goal of this study was to assess the urinary pattern of As methylation, including trivalent methylated metabolites, in an As-endemic population using freshly collected samples analyzed as soon as possible to avoid the oxidation of MAsIII and DMAsIII, even at temperatures < 0°C (Del Razo et al. 2001; Gong et al. 2001). Additionally, we compared the pattern of urinary trivalent methylated metabolites between persons with and without skin lesions associated with arsenicism in an endemic Mexican area.

We evaluated in Mexican children environmentally exposed to arsenic and lead monocyte nitric oxide (NO) and superoxide anion production in response to direct activation with interferon-gamma (IFN-gamma) + lipopolysaccharide (LPS). The integrity of Th1-regulated cellular immune response when monocytes were indirectly activated was also evaluated. Most children lived near a primary lead smelter. Lead and arsenic contamination in soil and dust by far exceeded background levels. As levels in water were between 10 and 30 ppb. Most children (93%) had urinary arsenic (AsU) concentrations above 50 microg/l (range 16.75-465.75) and 65% had lead blood levels (PbB) above 10 microg/dl (range 3.47-49.19). Multivariate analyses showed that NO production in monocytes activated indirectly was negatively associated with both PbB and AsU. Superoxide production in directly activated monocytes was negatively associated with AsU but positively associated with PbB. The models including the interaction term for AsU and PbB suggested the possibility of a negative interaction for NO production and a positive interaction for superoxide. There were indications of differential gender-based associations, NO production in indirectly activated monocytes obtained from girls was negatively associated with AsU but not with PbB. Superoxide production was positively associated with PbB in both directly and indirectly activated monocytes from boys but the latter was negatively associated with AsU. These effects are consistent with immune system abnormalities observed in human populations exposed to Pb or As. Further studies in larger populations are required to characterize As and Pb interactions and the mechanism(s) underlying the observed effects.

A recrudescent wave of pandemic influenza A/H1N1 affected Mexico during the winter of 2013-2014 following a mild 2012-2013 A/H3N2 influenza season.We compared the demographic and geographic characteristics of hospitalizations and inpatient deaths for severe acute respiratory infection (SARI) and laboratory-confirmed influenza during the 2013-2014 influenza season compared to previous influenza seasons, based on a large prospective surveillance system maintained by the Mexican Social Security health care system.A total of 14,236 SARI hospitalizations and 1,163 inpatient deaths (8.2%) were reported between October 1, 2013 and March 31, 2014. Rates of laboratory-confirmed A/H1N1 hospitalizations and deaths were significantly higher among individuals aged 30-59 years and lower among younger age groups for the 2013-2014 A/H1N1 season compared to the previous A/H1N1 season in 2011-2012 (χ(2) test, p0.001). The reproduction number for the winter 2013-2014 influenza season in central Mexico was estimated at 1.3-1.4, in line with that reported for the 2011-2012 A/H1N1 season but lower than during the initial waves of pandemic A/H1N1 activity in 2009.We documented a substantial increase in the number of A/H1N1-related hospitalizations and deaths during the period from October 2013-March 2014 in Mexico and a proportionate shift of severe disease to middle-aged adults, relative to the preceding A/H1N1 2011-2012 season. In the absence of clear antigenic drift in globally circulating A/H1N1 viruses in the post-2009 pandemic period, the gradual change in the age distribution of A/H1N1 infections observed in Mexico suggests a slow build-up of immunity among younger populations, reminiscent of the age profile of past pandemics.

This cross-sectional study examined the effects of chronic exposure to lead (Pb), arsenic (AS) and undernutrition on the neuropsychological development of children. Two populations chronically exposed to either high (41 children) or low (39 children) levels of As and Pb were analyzed using the Wechsler Intelligence Scale for Children, Revised Version, for México (WISC-RM). Geometric means of urinary arsenic (AsU) and lead in blood (PbB) were 62.9+/-0.03 (microgAs/g creatinine) and 8.9+/-0.03 (microg/dl) for the exposed group and 40.2+/-0.03 (microgAs/g creatinine) and 9.7+/-0.02 (microg/dl) for the reference group. The height for age index (HAI) was used as an indicator of chronic malnutrition and sociodemographic information was obtained with a questionnaire. Lead and arsenic were measured by atomic absorption spectrophotometry. Data on full, verbal, and performance intelligence quotients (IQ) scores, long-term memory, linguistic abstraction, attention span, and visuospatial organization were obtained through the WISC-RM. After controlling for significant potential confounders verbal IQ (P0.01) decreased with increasing concentrations of AsU. The HAI correlated positively with full-scale and performance IQ (P0.01). Higher levels of AsU were significantly related to poorer performance on WISC-RM factors examining long-term memory and linguistic abstraction, while lower scores in WISC-RM factors measuring attention were obtained at increasing values of PbB. Our results suggest that exposure to As and chronic malnutrition could have an influence on verbal abilities and long-term memory, while Pb exposure could affect the attention process even at low levels.

Background Increasing our understanding of the factors affecting the severity of the 2009 A/H1N1 influenza pandemic in different regions of the world could lead to improved clinical practice and mitigation strategies for future influenza pandemics. Even though a number of studies have shed light into the risk factors associated with severe outcomes of 2009 A/H1N1 influenza infections in different populations (e.g., [1-5]), analyses of the determinants of mortality risk spanning multiple pandemic waves and geographic regions are scarce. Between-country differences in the mortality burden of the 2009 pandemic could be linked to differences in influenza case management, underlying population health, or intrinsic differences in disease transmission [6]. Additional studies elucidating the determinants of disease severity globally are warranted to guide prevention efforts in future influenza pandemics. In Mexico, the 2009 A/H1N1 influenza pandemic was characterized by a three-wave pattern occurring in the spring, summer, and fall of 2009 with substantial geographical heterogeneity [7]. A recent study suggests that Mexico experienced high excess mortality burden during the 2009 A/H1N1 influenza pandemic relative to other countries [6]. However, an assessment of potential factors that contributed to the relatively high pandemic death toll in Mexico are lacking. Here, we fill this gap by analyzing a large series of laboratory-confirmed A/H1N1 influenza cases, hospitalizations, and deaths monitored by the Mexican Social Security medical system during April 1 through December 31, 2009 in Mexico. In particular, we quantify the association between disease severity, hospital admission delays, and neuraminidase inhibitor use by demographic characteristics, pandemic wave, and geographic regions of Mexico. Methods We analyzed a large series of laboratory-confirmed pandemic A/H1N1 influenza cases from a prospective surveillance system maintained by the Mexican Social Security system, April-December 2009. We considered a spectrum of disease severity encompassing outpatient visits, hospitalizations, and deaths, and recorded demographic and geographic information on individual patients. We assessed the impact of neuraminidase inhibitor treatment and hospital admission delay (≤ > 2 days after disease onset) on the risk of death by multivariate logistic regression. Results Approximately 50% of all A/H1N1-positive patients received antiviral medication during the Spring and Summer 2009 pandemic waves in Mexico while only 9% of A/H1N1 cases received antiviral medications during the fall wave (P Conclusions Our findings underscore the potential impact of decreasing admission delays and increasing antiviral use to mitigate the mortality burden of future influenza pandemics.

Background Some patients have a greater response to viral infection than do others having a similar level of viral replication. Hypercytokinemia is the principal immunopathological mechanism that contributes to a severer clinical course in cases of influenza A/H1N1. The benefit produced, or damage caused, by these cytokines in severe disease is not known. The genes that code for these molecules are polymorphic and certain alleles have been associated with susceptibility to various diseases. The objective of the present study was to determine whether there was an association between polymorphisms of TNF, LTA, IL1B, IL6, IL8, and CCL1 and the infection and severity of the illness caused by the pandemic A/H1N1 in Mexico in 2009. Methods Case–control study. The cases were patients confirmed with real time PCR with infection by the A/H1N1 pandemic virus. The controls were patients with infection like to influenza and non-familial healthy contacts of the patients with influenza. Medical history and outcome of the disease was registered. The DNA samples were genotyped for polymorphisms TNF rs361525, rs1800629, and rs1800750; LTA rs909253; IL1B rs16944; IL6 rs1818879; IL8 rs4073; and CCL1 rs2282691. Odds ratio (OR) and the 95% confidence interval (95% CI) were calculated. The logistic regression model was adjusted by age and severity of the illness in cases. Results Infection with the pandemic A/H1N1 virus was associated with the following genotypes: TNF rs361525 AA, OR = 27.00; 95% CI = 3.07–1248.77); LTA rs909253 AG (OR = 4.33, 95% CI = 1.82–10.32); TNF rs1800750 AA (OR = 4.33, 95% CI = 1.48–12.64); additionally, LTA rs909253 AG showed a limited statistically significant association with mortality (p = 0.06, OR = 3.13). Carriers of the TNF rs1800629 GA genotype were associated with high levels of blood urea nitrogen (p = 0.05); those of the TNF rs1800750 AA genotype, with high levels of creatine phosphokinase (p=0.05). The IL1B rs16944 AA genotype was associated with an elevated number of leukocytes (p IL8 rs4073 AA genotype, with a higher value for PaO2 mm Hg. Conclusion The polymorphisms of genes involved in the inflammatory process contributed to the severity of the clinical behavior of infection by the pandemic influenza A/H1N1 virus.

BackgroundElucidating the role of the underlying risk factors for severe outcomes of the 2009 A/H1N1 influenza pandemic could be crucial to define priority risk groups in resource-limited settings in future pandemics.MethodsWe use individual-level clinical data on a large series of ARI (acute respiratory infection) hospitalizations from a prospective surveillance system of the Mexican Social Security medical system to analyze clinical features at presentation, admission delays, selected comorbidities and receipt of seasonal vaccine on the risk of A/H1N1-related death. We considered ARI hospitalizations and inpatient-deaths, and recorded demographic, geographic, and medical information on individual patients during August-December, 2009.ResultsSeasonal influenza vaccination was associated with a reduced risk of death among A/H1N1 inpatients (OR = 0.43 (95% CI: 0.25, 0.74)) after adjustment for age, gender, geography, antiviral treatment, admission delays, comorbidities and medical conditions. However, this result should be interpreted with caution as it could have been affected by factors not directly measured in our study. Moreover, the effect of antiviral treatment against A/H1N1 inpatient death did not reach statistical significance (OR = 0.56 (95% CI: 0.29, 1.10)) probably because only 8.9% of A/H1N1 inpatients received antiviral treatment. Moreover, diabetes (OR = 1.6) and immune suppression (OR = 2.3) were statistically significant risk factors for death whereas asthmatic persons (OR = 0.3) or pregnant women (OR = 0.4) experienced a reduced fatality rate among A/H1N1 inpatients. We also observed an increased risk of death among A/H1N1 inpatients with admission delays >2 days after symptom onset (OR = 2.7). Similar associations were also observed for A/H1N1-negative inpatients.ConclusionsGeographical variation in identified medical risk factors including prevalence of diabetes and immune suppression may in part explain between-country differences in pandemic mortality burden. Furthermore, access to care including hospitalization without delay and antiviral treatment and are also important factors, as well as vaccination coverage with the 2008-09 trivalent inactivated influenza vaccine.

In April, 2009, the first cases of influenza A H1N1 were registered in Mexico and associated with an unexpected number of deaths. We report the timing and spread of H1N1 in cases, and explore protective and risk factors for infection, severe disease, and death.We analysed information gathered by the influenza surveillance system from April 28 to July 31, 2009, for patients with influenza-like illness who attended clinics that were part of the Mexican Institute for Social Security network. We calculated odds ratios (ORs) to compare risks of testing positive for H1N1 in those with influenza-like illness at clinic visits, the risk of admission for laboratory-confirmed cases of H1N1, and of death for inpatients according to demographic characteristics, clinical symptoms, seasonal influenza vaccine status, and elapsed time from symptom onset to admission.By July 31, 63 479 cases of influenza-like illness were reported; 6945 (11%) cases of H1N1 were confirmed, 6407 (92%) were outpatients, 475 (7%) were admitted and survived, and 63 (1%) died. Those aged 10-39 years were most affected (3922 [56%]). Mortality rates showed a J-shaped curve, with greatest risk in those aged 70 years and older (10.3%). Risk of infection was lowered in those who had been vaccinated for seasonal influenza (OR 0.65 [95% CI 0.55-0.77]). Delayed admission (1.19 [1.11-1.28] per day) and presence of chronic diseases (6.1 [2.37-15.99]) were associated with increased risk of dying.Risk communication and hospital preparedness are key factors to reduce mortality from H1N1 infection. Protective effects of seasonal influenza vaccination for the virus need to be investigated.None.

Exposure to naturally occurring inorganic arsenic (iAs), primarily from contaminated drinking water, is considered one of the top environmental health threats worldwide. Arsenic (+3 oxidation state) methyltransferase (AS3MT) is the key enzyme in the biotransformation pathway of iAs. AS3MT catalyzes the transfer of a methyl group from S-adenosyl-L-methionine to trivalent arsenicals, resulting in the production of methylated (MAs) and dimethylated arsenicals (DMAs). MAs is a susceptibility factor for iAs-induced toxicity. In this study, we evaluated the association of the polymorphism in AS3MT gene with iAs metabolism and with the presence of arsenic (As) premalignant skin lesions. This is a case-control study of 71 cases with skin lesions and 51 controls without skin lesions recruited from a iAs endemic area in Mexico. We measured urinary As metabolites, differentiating the trivalent and pentavalent arsenical species, using the hydride generation atomic absorption spectrometry. In addition, the study subjects were genotyped to analyze three single nucleotide polymorphisms (SNPs), A-477G, T14458C (nonsynonymus SNP; Met287Thr), and T35587C, in the AS3MT gene. We compared the frequencies of the AS3MT alleles, genotypes, and haplotypes in individuals with and without skin lesions. Marginal differences in the frequencies of the Met287Thr genotype were identified between individuals with and without premalignant skin lesions (p=0.055): individuals carrying the C (TC+CC) allele (Thr) were at risk [odds ratio=4.28; 95% confidence interval (1.0-18.5)]. Also, individuals with C allele of Met287Thr displayed greater percentage of MAs in urine and decrease in the percentage of DMAs. These findings indicate that Met287Thr influences the susceptibility to premalignant As skin lesions and might be at increased risk for other adverse health effects of iAs exposure.

People with less education in Europe, Asia, and the United States are at higher risk of mortality associated with daily and longer-term air pollution exposure. We examined whether educational level modified associations between mortality and ambient particulate pollution (PM10) in Latin America, using several timescales.The study population included people who died during 1998-2002 in Mexico City, Mexico; Santiago, Chile; and São Paulo, Brazil. We fit city-specific robust Poisson regressions to daily deaths for nonexternal-cause mortality, and then stratified by age, sex, and educational attainment among adults older than age 21 years (none, some primary, some secondary, and high school degree or more). Predictor variables included a natural spline for temporal trend, linear PM10 and apparent temperature at matching lags, and day-of-week indicators. We evaluated PM10 for lags 0 and 1 day, and fit an unconstrained distributed lag model for cumulative 6-day effects.The effects of a 10-microg/m increment in lag 1 PM10 on all nonexternal-cause adult mortality were for Mexico City 0.39% (95% confidence interval = 0.13%-0.65%); São Paulo 1.04% (0.71%-1.38%); and for Santiago 0.61% (0.40%-0.83%). We found cumulative 6-day effects for adult mortality in Santiago (0.86% [0.48%-1.23%]) and São Paulo (1.38% [0.85%-1.91%]), but no consistent gradients by educational status.PM10 had important short- and intermediate-term effects on mortality in these Latin American cities, but associations did not differ consistently by educational level.

Background Factors affecting vulnerability to heat-related mortality are not well understood. Identifying susceptible populations is of particular importance given anticipated rising temperatures from climatic change. Methods We investigated heat-related mortality for three Latin American cities (Mexico City, Mexico; Sao Paulo, Brazil; Santiago, Chile) using a case-crossover approach for 754 291 deaths from 1998 to 2002. We considered lagged exposures, confounding by air pollution, cause of death and susceptibilities by educational attainment, age and sex. Results Same and previous day apparent temperature were most strongly associated with mortality risk. Effect estimates remained positive though lowered after adjustment for ozone or PM10. Susceptibility increased with age in all cities. The increase in mortality risk for those ≥65 comparing the 95th and 75th percentiles of same-day apparent temperature was 2.69% (95% CI: −2.06 to 7.88%) for Santiago, 6.51% (95% CI: 3.57–9.52%) for Sao Paulo and 3.22% (95% CI: 0.93–5.57%) for Mexico City. Patterns of vulnerability by education and sex differed across communities. Effect estimates were higher for women than men in Mexico City, and higher for men elsewhere, although results by sex were not appreciably different for any city. In Sao Paulo, those with less education were more susceptible, whereas no distinct patterns by education were observed in the other cities. Conclusions Elevated temperatures are associated with mortality risk in these Latin American cities, with the strongest associations in Sao Paulo, the hottest city. The elderly are an important population for targeted prevention measures, but vulnerability by sex and education differed by city.

Paraoxonase (PON1) enzyme is associated with high-density lipoproteins (HDL) that prevents low-density lipoprotein (LDL) oxidation. PON1Q192R polymorphism is associated with a risk of coronary heart disease and low HDL levels in case-control studies, but the issue is yet unresolved. Mexico has shown an increase in cardiovascular diseases, and some genetic factors may play a role. Our purpose was to evaluate the association between PON1Q192R and L55M polymorphisms and serum lipid profile in a healthy Mexican population. Ninety unrelated male inhabitants from southeastern Mexico with Mayan ascendancy agreed to participate. Demographic characteristics, lifestyle and medical history were obtained by questionnaire. Lipid profile was determined by enzymatic methods, PON1 activity by using paraoxon and phenylacetate and PON1 genotype by real-time PCR. HDL-cholesterol (HDL-C) levels were associated with genotype: 192RR homozygote subjects had lower HDL-C levels than 192QQ homozygotes, and individuals with 192RR and 192QR genotypes had an odds ratio (OR)=7.05 (95% confidence interval (CI)=1.29-38.34) of having HDL-C60 mg/dL. Individuals with higher paraoxonase activity (600.18 U/L) had a slight risk (OR=4.9, 95% CI=0.83-22.02) of having HDL-C60 mg/dL. PON155LM polymorphism was associated with higher LDL-cholesterol. PON1Q192R polymorphism showed a role in modulating lipid profile: 192RR homozygotes showed the least favorable lipoprotein levels.

BackgroundMedical research has not been able to establish whether a father's occupational exposures are associated with the development of acute leukemia (AL) in their offspring. The studies conducted have weaknesses that have generated a misclassification of such exposure. Occupations and exposures to substances associated with childhood cancer are not very frequently encountered in the general population; thus, the reported risks are both inconsistent and inaccurate. In this study, to assess exposure we used a new method, an exposure index, which took into consideration the industrial branch, specific position, use of protective equipment, substances at work, degree of contact with such substances, and time of exposure. This index allowed us to obtain a grade, which permitted the identification of individuals according to their level of exposure to known or potentially carcinogenic agents that are not necessarily specifically identified as risk factors for leukemia. The aim of this study was to determine the association between a father's occupational exposure to carcinogenic agents and the presence of AL in their offspring.MethodsFrom 1999 to 2000, a case-control study was performed with 193 children who reside in Mexico City and had been diagnosed with AL. The initial sample-size calculation was 150 children per group, assessed with an expected odds ratio (OR) of three and a minimum exposure frequency of 15.8%. These children were matched by age, sex, and institution with 193 pediatric surgical patients at secondary-care hospitals. A questionnaire was used to determine each child's background and the characteristics of the father's occupation(s). In order to determine the level of exposure to carcinogenic agents, a previously validated exposure index (occupational exposure index, OEI) was used. The consistency and validity of the index were assessed by a questionnaire comparison, the sensory recognition of the work area, and an expert's opinion.ResultsThe adjusted ORs and 95% confidence intervals (CI) were 1.69 (0.98, 2.92) during the preconception period; 1.98 (1.13, 3.45) during the index pregnancy; 2.11 (1.17, 3.78) during breastfeeding period; 2.17 (1.28, 3.66) after birth; and 2.06 (1.24, 3.42) for global exposure.ConclusionThis is the first study in which an OEI was used to assess a father's occupational exposure to carcinogenic agents as a risk factor for the development of childhood AL in his offspring. From our results, we conclude that children whose fathers have been exposed to a high level of carcinogenic agents seem to have a greater risk of developing acute leukemia. However, confounding factors cannot be disregarded due to an incomplete control for confounding.

Aims: To evaluate the association between parental occupational exposure to agricultural work and the risk of anencephaly in three Mexican states. Methods: A paired case control study (1:1) was done based on records of the Epidemiological Surveillance System of Neural Tube Defects in Mexico; 151 cases of anencephaly of more than 20 weeks’ gestation were selected between March 2000 and February 2001. Controls were selected from the same maternity services as those of the cases and were born alive without congenital malformations. Information was obtained from both parents by means of a general questionnaire, a food frequency questionnaire, and a specific questionnaire on occupational exposure to pesticides. Exposures were analysed with emphasis on the three months before and one month after the last menstruation periods (acute risk period (ARP)), as well as exposure prior to the abovementioned period (non-acute risk period (NARP)). Results: The children of mothers who worked in agriculture in the ARP had a greater risk of anencephaly (OR = 4.57, 95% CI 1.05 to 19.96). The risk of fathers having a child with anencephaly was greater in those who applied pesticides irrespective of whether it was done in the ARP or the NARP (OR = 2.50, 95% CI 0.73 to 8.64; and OR = 2.03, 95% CI 0.58 to 7.08, respectively). Conclusions: These results support the hypothesis of the effect of maternal exposure to agricultural work on anencephaly and suggest that exposure of the father to pesticides in the periconceptional period or prior to this can also increase the risk of having an anencephalic child.

To estimate the prevalence of oral product use in children less than three years of age, and to measure the concentration of phthalates as potentially toxic products.In 1999, 199 mothers of children living in the city of Toluca agreed to household interviews. Samples of oral products used by the children were taken and analyzed by gas chromatography to identify and quantify phthalate concentrations, to estimate the daily intake of phthalates from this source.The prevalence of oral product use was 13%. Male infants less than 18 months of age of low socioeconomic level used them more frequently. The concentrations ranged from traces to 67% weight. The mean exposure to products manufactured with polyvinyl chloride and phthalates was 13.94 microg/kg/day (95% CI 9.08, 18.89).The daily dose of phthalate intake from products for infants to suck or bite did not exceed the recommended limit established in other countries. Nevertheless, other sources can contribute to increase the total dose. Since some phthalates are harmful to the reproductive system in animals and this potential effect may also be expected in humans, it is necessary to assess other sources and determine exposure using biomarkers.

We assessed the relationships between chronic arsenic (As) exposure, human papilloma virus (HPV) contact and non-melanoma skin cancer (NMSC) by means of a dermatology clinic-based case-control study (42 cases and 48 controls) in Region Lagunera, Mexico, where chronic As poisoning is endemic. Exposure was determined through detailed history of residence in the As-contaminated area and measurement of As levels in drinking water and urine. We used a consensus epitope from the central region of L1 protein of the HPV family to determine antibodies against HPV. A history of As exposure and HPV seropositivity were associated with increased NMSC risks. A history of exposure to high levels of As increased the risk for NMSC (OR = 4.53; P = 0.11) in the group of seronegative HPV patients. A positive response to HPV significantly increased the OR for NMSC to 9.04 (P = 0.01) when history showed exposure to low levels of As. Interestingly, the OR was significantly increased to 16.5 (P = 0.001) when both exposure to high levels of As and HPV seropositivity were present. In addition, the presence of NMSC increased the OR (5.45; P = 0.03) for a positive response to HPV when history showed exposure to low levels of As, but the OR was increased to 8.0 (P = 0.005) in the cases with high exposure levels. Thus, HPV infection could constitute an additional risk factor for NMSC development in humans chronically exposed to As. However, further studies with additional populations are needed to determine the interaction between HPV and As exposure in NMSC.

Fluoride-induced reproductive effects have been reported in experimental models and in humans. However, these effects were found in heavily exposed scenarios. Therefore, in this work our objective was to study reproductive parameters in a population exposed to fluoride at doses of 3–27 mg/day (high-fluoride-exposed group—HFEG). Urinary fluoride levels, semen parameters, and reproductive hormones in serum (LH, FSH, estradiol, prolactin, inhibin-B, free and total testosterone) were measured. Results were compared with a group of individuals exposed to fluoride at lower doses: 2–13 mg/day (low-fluoride-exposed group—LFEG). A significant increase in FSH (P

To describe spirometric reproducibility in a longitudinal study of students from Mexico City, and also the frequency of subjects fulfilling quality criteria proposed for children.Three thousand three hundred forty-seven participants from the third through sixth grades of elementary school were recruited to perform biannual spirometry, yielding a maximum of seven evaluations and a total of 15,563 tests. Standard recommendations of the American Thoracic Society (ATS) were followed, using dry rolling-seal volume spirometers.During their first spirometric test,95% of the subjects fulfilled each of the quality criteria proposed by ATS for adults, though not all of them did so simultaneously. For example, only 72.4% obtained three acceptable maneuvers, reproducibility for FEV(1) and FVC to200 mL, and a small back-extrapolated volume that increased to 92.3% by the second test. Between phase 1 and phase 7 of the study, spirometry quality increased significantly, as a result of subject and technician training. Intratest and intertest (with a 6-month difference) spirometric variability was less in boys than in girls. Intratest variability was also lower in younger and taller subjects. Technicians contributed significantly to intratest and intertest variability, the latter decreasing if the same technician performed both evaluations.Children7 years old can fulfill ATS criteria of quality after the first spirometric evaluation. To maintain quality of spirometric tests in longitudinal studies of children, a strict control is required, especially of technician performance.

To assess potential effects of human DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane] exposure, we evaluated the reproductive history of 2,033 workers in the antimalaria campaign of Mexico. Data on occupational exposure to DDT and reproductive outcomes were gathered through a questionnaire, and workers provided information about 9,187 pregnancies. We estimated paternal exposure to DDT before each pregnancy using three approaches: a) a dichotomous indicator for pregnancies before and after exposure began, b) a qualitative index of four exposure categories, and c) an estimation of the DDT metabolite DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] accumulated in fat. To assess associations, we used logistic regression models that accounted for correlated observations and adjusted for parents' age at each child's birth, exposure to other pesticides, exposure to chemical substances in other employment, smoking, and alcohol consumption. The odds ratio for birth defects comparing pregnancies after and before the first exposure was 3.77 [95% confidence interval (95% CI), 1.19-9.52]. Compared with the lowest quartile of estimated DDE in fat, the ORs were 2.48 (95% CI, 0.75-8.11), 4.15 (95% CI, 1.38-12.46), and 3.76 (95% CI, 1.23-11.44) for quartiles 2, 3, and 4, equivalent to p,p -DDE in fat of 50, 82, and 298 microg/g fat, respectively. No significant association was found for spontaneous abortion or sex ratio. We found an increased risk of birth defects associated with high occupational exposure to DDT in this group of workers. The significance of this association at lower exposure levels found in the general population remains uncertain.

Background Permanent occupational disability is one of the most severe consequences of diabetes that impedes the performance of usual working activities among economically active individuals. Survival rates and worker compensation expenses have not previously been examined among Mexican workers. We aimed to describe the worker compensation expenses derived from pension payments and also to examine the survival rates and characteristics associated with all-cause mortality, in a cohort of 34,014 Mexican workers with permanent occupational disability caused by diabetes during the years 2000–2013 at the Mexican Institute of Social Security. Methods A cross-sectional analysis study was conducted using national administrative records data from the entire country, regarding permanent occupational disability medical certification, pension payment and vital status. Survival rates were estimated using the Kaplan–Meier method. Multivariate Cox proportional hazard model was used to estimate adjusted hazard ratios (HR) and 95 % confidence intervals (95 % CI) in order to assess the cohort characteristics and all-cause mortality risk. Total expenses derived from pension payments for the period were accounted for in U.S. dollars (USD, 2013). Results There were 12,917 deaths in 142,725.1 person-years. Median survival time was 7.26 years. After multivariate adjusted analysis, males (HR, 1.39; 95 % CI, 1.29–1.50), agricultural, forestry, and fishery workers (HR, 1.41; 95 % CI, 1.15–1.73) and renal complications (HR, 3.49; 95 % CI, 3.18–3.83) had the highest association with all-cause mortality. The all-period expenses derived from pension payments amounted to $777.78 million USD (2013), and showed a sustained increment: from $58.28 million USD in 2000 to $111.62 million USD in 2013 (percentage increase of 91.5 %). Conclusions Mexican workers with permanent occupational disability caused by diabetes had a median survival of 7.26 years, and those with renal complications showed the lowest survival in the cohort. Expenses derived from pension payments amounted to $ 777 million USD and showed an important increase from 2000 to 2013.