Association of tyrosine hydroxylase 01 (TH01) microsatellite and insulin gene (INS) variable number of tandem repeat (VNTR) with type 2 diabetes and fasting insulin secretion in Mexican population.

PURPOSE: A variable number of tandem repeats (VNTR) in the insulin gene (INS) control region may be involved in type 2 diabetes (T2D). The TH01 microsatellite is near INS and may regulate it. We investigated whether the TH01 microsatellite and INS VNTR, assessed via the surrogate marker single nucleotide polymorphism rs689, are associated with T2D and serum insulin levels in a Mexican population. METHODS: We analyzed a main case-control study (n = 1986) that used univariate and multivariate logistic regression models to calculate the risk conferred by TH01 and rs689 loci for T2D development; rs689 results were replicated in other case-control (n = 1188) and cross-sectional (n = 1914) studies. RESULTS: TH01 alleles 6, 8, 9, and 9.3 and allele A of rs689 were independently associated with T2D, with differences between sex and age at diagnosis. TH01 alleles with ≥ 8 repeats conferred an increased risk for T2D in males compared with ≤ 7 repeats (odds ratio, ≥ 1.46; 95% confidence interval, 1.1-1.95). In females, larger alleles conferred a 1.5-fold higher risk for T2D when diagnosed ≥ 46 years but conferred protection when diagnosed ≤ 45 years. Similarly, rs689 allele A was associated with T2D in these groups. In males, larger TH01 alleles and the rs689 A allele were associated with a significant decrease in median fasting plasma insulin concentration with age in T2D cases; the reverse occurred in controls. CONCLUSION: Larger TH01 alleles and rs689 A allele may potentiate insulin synthesis in males without T2D, a process disabled in those with T2D.

Mexican anthropometric percentiles for ages 10-18.

OBJECTIVE: To elaborate Mexican growth charts based on international methodology. DESIGN: Data were obtained from the Mexican National Health Survey. The survey was stratified and probabilistic representative of all the country. SETTING: Nationwide open population living in urban and rural areas. SUBJECTS: Boys (8545) and girls (9983) from 10 to 18 years participating in the survey. METHODS: Age, weight and height were recorded. Empirical percentiles were calculated and smoothed. Smoothed curves were approximated using least-mean square estimation. RESULTS: Tables and figures for percentile values of weight, height and body mass index (BMI) for age, as well as percentile values of weight and BMI for height for both genders are presented. Regarding 50th BMI for age percentiles, Mexicans had higher levels than the Americans in the Centers for Disease Control and Prevention growth charts; Mexicans were lower but had similar weights than the Americans. Owing to the high BMI, the percentile corresponding to an overweight level (25 kg/m(2)) at 18 years was 74.5 in boys and 72.5 in girls, whereas obesity level (30 kg/m(2)) at 18 years was 97.3 and 97.4 in boys and girls, respectively. CONCLUSIONS: The present growth charts are snapshots of a Mexican population. Because of the high median BMI compared to US and World Health Organization standards, we must be cautious in establishing an upper normal cutoff for clinical normality, not merely selecting the 85th and 95th percentiles as equivalents of overweight and obesity, respectively. Therefore, we proposed percentiles 74.5 in boys and 72.5 in girls as the action points of overweight as they are the percentiles corresponding to BMI 25 kg/m(2) at 18 years. SPONSORSHIP: The survey was supported by the Mexican Minister of Health. Statistical analyses were sponsored by Dr Del-Rio-Navarro.

Survey of drug resistance of Mycobacterium tuberculosis in 3 Mexican states, 1997.

BACKGROUND: Drug resistance threatens global tuberculosis (TB) control efforts. Population-based estimates of drug resistance are needed to develop strategies for controlling drug-resistant TB in Mexico. OBJECTIVE: To obtain population-based data on Mycobacterium tuberculosis drug resistance in Mexico. METHODS: To obtain drug resistance data, we conducted a population-based study of TB cases in the states of Baja California, Sinaloa, and Oaxaca, Mexico. We performed cultures and drug susceptibility testing on M tuberculosis isolates from patients with newly diagnosed, smear-positive TB from April 1 to October 31, 1997. RESULTS: Mycobacterium tuberculosis was isolated from 460 (75%) of the 614 patients. Levels of resistance in new and retreatment TB cases to 1 or more of the 3 current first-line drugs used in Mexico (isoniazid, rifampin, and pyrazinamide) were 12.9% and 50.5%, respectively; the corresponding levels of multi-drug-resistant TB were 2.4% and 22.4%. Retreatment cases were significantly more likely than new cases to have isolates resistant to 1 or more of the 3 first-line drugs (relative risk [RR], 3.9; 95% confidence interval [CI], 2.8-5.5), to have isoniazid resistance (RR, 3.6; 95% CI, 2.5-5.2), and to have multi-drug-resistant TB (RR, 9.4; 95% CI, 4.3-20.2). CONCLUSIONS: This population-based study of M tuberculosis demonstrates moderately high levels of drug resistance. Important issues to consider in the national strategy to prevent M tuberculosis resistance in Mexico include consideration of the most appropriate initial therapy in patients with TB, the treatment of patients with multiple drug resistance, and surveillance or periodic surveys of resistance among new TB patients to monitor drug resistance trends.

Cholesterol levels and prevalence of hypercholesterolemia in Mexican children and teenagers.

In Mexico, the incidence and prevalence of coronary heart disease has increased over the past three decades and has become the leading cause of death in some areas of the country. Hypercholesterolemia (HC) is a major risk factor for coronary atherosclerosis and most developed countries currently have public health strategies that attempt to reduce the level of cholesterol. In order to learn the mean total cholesterol values and the prevalence of HC, an epidemiologic survey was carried out in a representative population sample that included men and women aged 1 to 98 years, across the nation. In this report, we present the findings in children and teenagers of both sexes (n = 34369). Considering the country as a whole, the mean serum TC was 147 +/- 35 mg/dl, the prevalence of borderline hypercholesterolemia (TC between 170 and 199 mg/dl) was 14.7% and the prevalence of high risk hypercholesterolemia (TC > or = 200 mg/dl) was 6.7%. This cross sectional study demonstrated the existence of significant geographic differences in serum TC, with mean state values ranging from 133 mg/dl in the south to 164 mg/dl in the north. The prevalences of high risk hypercholesterolemia was as high as 18.2% in Baja California Norte and as low as 2.5% in the state of Morelos. These geographic differences in total cholesterol and prevalence of hypercholesterolemia were already present at one year of age and persisted throughout childhood and adolescence.

Cholesterol levels and prevalence of hypercholesterolemia in a Mexican adult population.

In Mexico, the incidence and prevalence of coronary heart disease (CHD) has increased over the past three decades and has become the leading cause of death in the country. Hypercholesterolemia is a major risk factor for coronary atherosclerosis and most developed countries currently have public health strategies that attempt to reduce the level of cholesterol. In order to determine the mean total cholesterol values and the prevalence of hypercholesterolemia, an epidemiologic survey was carried out in a representative national population sample that included men and women aged 1 to 98 years. In this report, we present the findings in all individuals older than 20 years (n = 33,558). Considering the country as a whole, the mean serum total cholesterol (TC) was 4.80 +/- 1.16 mmol/l, the prevalence of borderline hypercholesterolemia (TC between 5.17 and 6.20 mmol/l) was 22.8% and the prevalence of high risk hypercholesterolemia (TC > or = 6.20 mmol/l) was 10.6%. This cross sectional study demonstrated the existence of significant geographic differences in serum TC, with mean state values ranging from 4.43 +/- 1.05 mmol/l in the south to 5.48 +/- 1.36 mmol/l in the north. The prevalence of high risk hypercholesterolemia was as high as 24.8% in Baja California Norte and as low as 4.0% in the state of Guerrero. These large differences in mean TC values are probably diet related and reinforce the need to carry out prospective and intervention trials related to CHD and its risk factors.

Serologic IgG response to urease in Helicobacter pylori-infected persons from Mexico.

Helicobacter pylori urease is required to counteract acidity during colonization of the stomach, and has been suggested as a major immunodominant antigen. The aim of this study was to determine the anti-urease response in a representative national serologic survey in Mexico. The population surveyed included persons 1-90 years of age from all socioeconomic levels and geographic zones of the country. Helicobacter pylori status was determined by ELISA serology. The IgG anti-urease was studied by ELISA using a recombinant apoenzyme. We found that 2,930 of the 7,720 infected patients (38%) were seropositive for IgG urease. The rate of IgG anti-urease positivity increased with age; in children < 10 years old it was < 20% and in persons > 40 years old it was > 50%. Age and a region with a high level of development were risk factors for seropositivity, whereas gender, educational level, crowding, and socioeconomic level were not associated with seropositivity. In conclusion, in natural infection with H. pylori, the response to urease is poor, mainly during the first years of infection. This inconsistent immune response to the enzyme may favor persistence of infection. A vaccine eliciting a consistent anti-urease response might overcome immune evasion and enhance clearance of bacteria after exposure.

Hepatitis A in Latin America: a changing epidemiologic pattern.

In a multicenter study, hepatitis A virus (HAV) seroprevalence was surveyed in six countries in Latin America in which in 12,000 subjects were stratified for age. The highest rates of seroprevalence were recorded in the Dominican Republic (89.0%) and Mexico (81.0%), with lower rates in Brazil (64.7%), Chile (58.1%), Venezuela (55.7%), and Argentina (55.0%). The seroprevalence of HAV in children between 1 and 5 years of age was less than 50%, except in the Dominican Republic. In the 5-10-year-old age group, seroprevalence rates have also decreased compared with previous reports. This suggests that the epidemiology is shifting from high to intermediate endemicity, with the population susceptible to HAV infection shifting from children to adolescents and adults. Furthermore, data from Brazil, Argentina, and Mexico show that HAV seroprevalence is significantly lower in people living in medium and high socioeconomic conditions. This study suggests the need for appropriate vaccination programs to be implemented targeting children, adolescents, and adults, particularly in higher socioeconomic groups.

Seroepidemiology of amebiasis in Mexico.

The presence of serum antibodies to Entamoeba histolytica was detected by indirect hemagglutination in a representative sample of the 32 federal entities of the Mexican Republic. This study was designed to include biologic, geographic, social, economic, and educational variables. The total percentage of positive sera was 8.41%. Seroprevalence varied with geographic zones, with the South Central, South Pacific, and Yucatan Peninsula areas showing the highest values (> or = 9%), and the North, Northeast, and Gulf of Mexico areas showing the lowest values (< or = 8.0%). Seroprevalence of anti-E. histolytica antibodies seemed to increase from the northern regions to the southern areas of Mexico. These results indicated that amebiasis is endemic in the Mexican Republic, with areas of high seroprevalence not related to climatic conditions. Exposure to infectious contact with E. histolytica occurred at all ages, with a higher frequency at school age.

Risk factors for inhalant abuse in juvenile offenders: the case of Mexico.

During the last two decades the abuse of inhalants and other addictive substances has received considerable attention in Mexico. Although substance abuse seems to affect everyone, adolescents seem to be at higher risk, and although researchers have identified the links between substance abuse and delinquency, there is not enough scientific information to explain the reason. A cross-sectional study was designed to examine the relationship between known risk factors and inhalant abuse among a group of Mexican juvenile offenders. Of the 626 subjects studied, 58% reported use of different drugs, and of them 23% abused inhalants. Gender, low socio-economic level and labor status were the principal risk factors associated with inhalant abuse. According to attributable risks calculated, and taking into account the methodological limitations of the study, the authors suggest some preventive actions to decrease inhalant abuse in the population studied.

Hypertension in urban Mexico: the 1992-93 national survey of chronic diseases.

The purpose of this work is to estimate the prevalence of hypertension in the urban population of Mexico. We studied a multistage national sample representative of the urban population in 417 cities of over 2500 people. The blood pressure of 14 657 individuals (6053 men and 8604 women) aged 20-69 years was measured after a 5-min rest using a standard mercury sphygmomanometer. The survey personnel had been previously trained and standardised. The main results show a crude prevalence of hypertension, as defined by the JNC VI, of 28.1% in women and 37.5% in men (27.2% and 37.1% age-adjusted). Both genders exhibited a trend of increasing hypertension with age. In individuals under 50 years of age, women had lower rates than men, but the difference disappeared in the older groups. The awareness of hypertension (28%) as well as the success of treatment (22%) were low in our sample. Our results had more similarities than differences with respect to those observed in other national surveys. It is concluded that hypertension in Mexico is an important public health problem similar to that seen in developing and developed nations. Efforts should be aimed at strengthening measures to prevent and control hypertension in Mexico. More information is needed of the sort obtained from longitudinal studies.

Serologic evidences suggesting the presence of Borrelia burgdorferi infection in Mexico.

BACKGROUND: Lyme disease is the most common vector-borne human disease in Europe and the United States. In Mexico, clinical cases suggestive of Lyme borreliosis have been reported; however, infection was not confirmed by serologic or microbiologic tests. METHODS: To study the prevalence of IgG antibodies against Borrelia burgdorferi among Mexican persons, a community-based sero-survey including all states of Mexico was done. A sample of 2,890 sera representing individuals of all ages and all socioeconomic levels was studied. Antibodies anti-B. burgdorferi were determined by enzyme-linked immunosorbent assay (ELISA) using a whole-cell sonicated extract of B. burgdorferi strain B31. Serum specimens positive for ELISA were further studied by Western blot (WB). A serum sample was considered positive by WB if at least three of the following protein bands were recognized: 18, 24, 28, 29, 31, 34, 39, 41, 45, 58, 62, 66, and 93 kDa. Some WB positive specimens were further confirmed with an immunodot-blot (IDB) test using recombinant and purified B. burgdorferi proteins. RESULTS: Of the 2,890 specimens, 34 were positive for ELISA; nine of these 34 were confirmed as positive by WB. Four of the nine WB positive sera were tested by IDB and all four were positive. The prevalence of WB confirmed cases in the sample studied was 0.3%. Positive specimens were from residents of the northeastern and central areas of Mexico. CONCLUSIONS: The serological evidences of this study suggest that Borrelia burgdorferi infection is present in the Mexican population. This finding should be confirmed by documenting the infection in clinical cases and in tick vectors.

Seroepidemiology of hepatitis E virus infection in Mexican subjects 1 to 29 years of age.

BACKGROUND: Hepatitis E virus (HEV) infection causes an acute, self-limited hepatitis associated with high mortality in pregnant women. Community-based surveys are scarce and information on HEV infection in populations is needed. The aim of this work was to study seroprevalence to HEV in young adults and children in Mexico, using a community-based survey. METHODS: Serum samples from 3,549 individuals were studied; the population included subjects from 1 to 29 years old from all regions of the country representing all socioeconomic levels. IgG anti-HEV was determined by ELISA. RESULTS: Anti-HEV antibodies were found in 374 (10.5%) individuals. Seroprevalence increased with age from 1.1% in children younger than 5 years to 14.2% in persons 26 to 29 years of age (p = 0.006). Risk factors for infection included living in rural communities and a low educational level. Seroprevalence was not associated with the level of regional development. CONCLUSIONS: HEV infection is endemic in Mexico. Age, type of community, and educational level were identified as risk factors for infection.

Susceptibility to varicella-zoster infection in individuals 1 to 29 years of age in Mexico.

BACKGROUND: The prevalence of varicella zoster virus (VZV) infection has been poorly studied in Latin America. The aim of this work was to study the seroprevalence of antibody to VZV infection in Mexico. Infection was determined in 3,737 individuals. METHODS: Samples were collected during a national serologic survey performed during 1987-1988 and represented individuals 1- to 29-years-old from all socioeconomic levels and from rural and urban communities throughout the country. Antibodies anti-VZV were measured with a commercially available enzyme-linked immunosorbent assay (VARELISA Merck, Germany). RESULTS: In the population studied, 464 individuals (12.4%) were seronegative or susceptible to infection, whereas about 17.0% of individuals 1- to 19-years-old were susceptible to infection. Between the ages of 20 to 24 years, 8.4% were susceptible and between 25 to 29 years, 5.0% of persons were still susceptible to infection. CONCLUSIONS: Socioeconomic level, density of population, crowding, and gender were not found as risk factors for susceptibility to VZV infection in adolescents and young adults. Low educational level was found as a risk factor for susceptibility. High proportions of adolescents and young adults in Mexico are susceptible to VZV infection and should receive special attention when designing vaccination programs.

[Molecular epidemiology in the epidemiological transition]. / La epidemiología molecular en la transición epidemiológica.

The epidemiological transition describes the changes in the health profile of populations where infectious diseases are substituted by chronic or non-communicable diseases. Even in industrialized countries, infectious diseases emerge as important public health problems and with a very important association with several type of neoplasm. Molecular epidemiology brings in new tools for the study of the epidemiological transition by discovering infectious agents as etiology of diseases, neither of both new. Much has been advanced in the understanding of the virulence and resistance mechanism of different strains, or improving the knowledge on transmission dynamics and dissemination pathways of infectious diseases. As to the non-communicable diseases, molecular epidemiology has enhanced the identification of endogenous risk factors link to alterations, molecular changes in genetic material, that will allow a more detail definition of risk and the identification of individual and groups at risk of several diseases. The potential impact of molecular epidemiology in other areas as environmental, lifestyles and nutritional areas are illustrated with several examples.

[Mortality and possible lost years of life due to tobacco consumption in Mexico]. / Mortalidad y años de vida potencial perdidos por consumo de tabaco en México.

An analysis was performed to estimate mortality and YPLL attributable to 20 smoking related diseases, based on the prevalence rates of current and former smokers obtained from a national survey; mortality data from vital statistics, and their relative risks and attributable mortality fractions due to tobacco consumption of the 20 diagnoses set for 1986. Numerical estimates of national mortality and YPLL attributable to cigarette consumption for the diagnosis set were made. Among the population of 20 years of age and older on 1986, a total of 17,405 deaths where attributable to smoking cases (47.0/100,000 individuals of 20 to 74 years of age), and takes the 9th place of grouped general mortality. Cardiovascular disease rated first place with 33 per cent of total cases; respiratory disease came second with 31.6 per cent. All 20 diagnoses someans 146.299 YPLL between 20 to 65 years (1.4 per cent from total ypll 0-70 years).