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.

P3824Body composition and mortality from vascular or metabolic causes among 150,000 participants in the Mexico City Prospective Study

Background

Higher body-mass index is associated with increased mortality from vascular disease, renal disease and other metabolic causes. However, body mass reflects both fat and lean mass, which may have very different effects on risk. We investigated the individual and joint relevance of fat and lean mass to mortality from these causes, using data from the Mexico City Prospective Study.

Methods

Between 1998 and 2004, 150,000 adults from Mexico City were recruited into a prospective study and tracked for cause-specific mortality for 14 years. Fat and lean mass at recruitment were predicted using Mexican-specific anthropometric equations, validated in a subset of participants with additional bio-impedance measures. Cox regression was used to assess the relevance of fat and lean mass at recruitment to mortality from a vascular, renal, or other metabolic cause at ages 35–74 years. Analyses were adjusted for age at risk, sex, residential district, education, recreational physical activity, smoking and alcohol consumption. To avoid reverse causality, analyses excluded those with diabetes or other chronic diseases at recruitment, and deaths in the first 5 years of follow-up. Mortality rate ratios (RRs) relate to the differences per SD of the usual values of various factors or the differences between the top tenth and bottom fifth of the values.

Results

Among 112,923 participants aged 35–74 years, mean (SD) fat mass in men and women was 22.0 (6.4) kgs and 29.4 (7.8) kgs respectively, while mean (SD) lean mass was 54.9 (7.2) kgs and 39.2 (5.0) kgs respectively. In both men and women, equation-predicted fat and lean mass closely matched the bio-impedance values (all r>0.86). Both fat and lean mass were positively and approximately log-linearly associated with mortality from a vascular or metabolic cause. However, the association of lean mass with mortality was more than accounted for by the correlation of lean with fat mass. Hence, after adjustment for fat mass, lean mass was inversely associated with risk. For a given amount of fat mass, the RR for vascular/metabolic mortality comparing those in the top tenth versus bottom fifth of the predicted lean mass was 0.35 (95% CI 0.24–0.52). Conversely, for a given amount of lean mass, the RR comparing those in the top tenth versus bottom fifth of the predicted fat mass was 4.06 (3.06–5.39). The RRs associated with each SD higher fat mass (1.51, 1.40–1.63) or lean mass (0.79, 0.73–0.86) appeared to be little affected by age, sex, or levels of other confounders, and were broadly similar for the major vascular, renal, and other metabolic mortality. The height-adjusted RRs were 1.41 (1.30–1.53) for fat mass and 0.91 (0.82–1.00) for lean mass.

Conclusions

In this Mexican cohort, predicted fat and lean mass had opposing effects on vascular and other metabolic deaths, with no evidence of any thresholds throughout the ranges studied.

Cardiovascular risk factors in the urban Mexican population: The FRIMEX study

BACKGROUND

Atherosclerotic ischaemic heart disease is the second leading cause of general mortality in Mexico due to the growing prevalence of atherosclerotic risk factors in our society. The data of the FRIMEX study (Factores de Riesgo en México, Risk Factors in Mexico), considered together with those of other contemporary epidemiological surveys, will aid in our comprehension of the current state of cardiovascular epidemics in Mexico.

METHODS

Frequencies of obesity, hypertension and smoking, and total cholesterol and glucose in capillary blood were estimated in a non-probabilistic sample comprised of 140017 individuals (aged 44+/-13 years; 42% men and 58% women), from six Mexican cities (Mexico City, Guadalajara, Monterrey, Puebla, Leon and Tijuana).

RESULTS

Obesity or overweight status was found in 71.9% of participants. Hypertension was found in 26.5%, and the proportions of awareness, treatment and control for this disease were 49.3, 73 and 36%, respectively. Prevalence of hypertension increased with age; while it was higher in men under 60 years of age, in the more aged individuals it was higher in women. Hypercholesterolaemia was found in 40% of the individuals and cholesterolaemia > or =240 mg/dl was significantly higher in women. Thirty-five and a half percent of men and 18.1% of women were smokers. Type 2 diabetes mellitus was found in 10.4% of participants. There was significant Pearson's correlation between body mass index and blood pressure, between hypertension and glucose levels, and between hypertension and total cholesterol concentrations.

CONCLUSIONS

We conclude that this population has a high cardiovascular risk profile and a high probability of the occurrence of metabolic syndrome.

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.

The body mass index is a less-sensitive tool for detecting cases with obesity-associated co-morbidities in short stature subjects

OBJECTIVE

To assess the ability of the body mass index (BMI) to detect obesity-associated morbidity in subjects with a normal or short stature.

METHODS

Information was obtained on 119 975 subjects from a cardiovascular risk factors detection program. Standardized questionnaires were used. Capillary glucose and cholesterol concentrations were measured. Diabetes, arterial hypertension and hypercholesterolemia were selected as end points. Sensitivity, specificity and the likelihood ratio for several BMI thresholds were calculated. ROC curves were constructed to identify the BMI cutoff points with best diagnostic performance. The area under the curve (AUC) was used to assess the proficiency of BMI.

RESULTS

Short stature (height </=150 cm for women or </=160 cm for men) was found in 24 854 subjects (20.7%). These cases had a higher prevalence of type II diabetes and arterial hypertension even after adjusting for confounding variables. In addition, the frequency of the abnormalities was higher even at the lowest BMI values; the prevalence increased in direct proportion with the BMI, but at a lower rate compared to cases with normal stature. The AUC for every co-morbidity was smaller in short stature subjects. The likelihood ratio for detecting co-morbidities increased at the same BMI value in subjects with or without short stature.

CONCLUSIONS

The prevalence of obesity-associated co-morbidities is higher in subjects with short stature compared to those without it. The proficiency of BMI as a diagnostic tool is poor in short stature subjects. This problem is not resolved by decreasing BMI thresholds used to define overweight.

Evaluation and reform of Mexican National Epidemiological Surveillance System

To generate timely and reliable information for decision making in local health centers, Mexico's National Epidemiological Surveillance System (SINAVE) was evaluated and reformed. The reform was achieved by consensus through national meetings of epidemiologists, using a conceptual model of requirements, leadership, participation, and motivation. The new SINAVE is run by committees that use data from 16 468 local health centers that generate homogeneous information from all health institutions. Indicators, flowcharts, and standardized instruments were created. The reforms modernized SINAVE and strengthened epidemiologists' leadership, consolidated local decision making, and assessed control actions needed to improve the health of the Mexican population.

[Epidemiologic overview of smoking in Mexico]

Smoking is one of the main preventable causes of disease and death worldwide; 3.5 million smokers die annually. This essay shows the progress made against this epidemic in our country and points out the relevance of implementing a comprehensive program to control smoking. Results from three national surveys conducted in Mexico in 1988, 1993, and 1998 are analyzed and compared. On the one hand, the strategies should include preventive actions, protection of non-smokers, smoking cessation, banning of smoking advertisement, and tax increases; on the other hand, controlling smoking and its consequences on health depend on all of us.

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.

Prevalence of pre-obesity and obesity in urban adult Mexicans in comparison with other large surveys

OBJECTIVE

1. To estimate the prevalence of pre-obesity and obesity in a 1992 to 1993 national survey of the Mexican urban adult population. 2. To compare our findings with other national surveys and with data for Mexican Americans.

RESEARCH METHODS AND PROCEDURES

The national representative sample of the Mexican urban adult population included 8462 women and 5929 men aged 20 to 69 years from 417 towns of >2500 people. Body mass index (BMI), calculated from measured weight and height, was classified using the World Health Organization categories of underweight (BMI < 18.5 kg/m2), normal weight (BMI 18.5 to 24.9 kg/m2), pre-obesity (PreOB = BMI 25 to 29.9 kg/m2) and obesity (OB = BMI 30+ kg/m2). Estimates for Mexican Americans were calculated from U.S. survey data.

RESULTS

Overall, 38% of the Mexican urban adult population were classified as pre-obese and 21% as obese. Men had a higher prevalence of pre-obesity than women did at all ages, but women had higher values of obesity. Both pre-obesity and obesity increased with age up to the age range brackets of 40 to 49 or 50 to 59 years for both men and women. Both pre-obesity and obesity prevalence estimates were remarkably similar to data for Mexican Americans from 1982 through 1984. Comparison with other large surveys showed that countries differed more in the prevalence of obesity than of pre-obesity, leading to differences in the PreOB/OB ratio, and that countries also differed in the gender ratio (female/male) for both pre-obesity and obesity.

DISCUSSION

Pre-obesity and obesity were high in our population and increased with age. Our approach of characterizing large surveys by PreOB/OB and gender ratios appeared promising.

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.

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.

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.

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.

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.

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.

A community-based seroepidemiologic study of Helicobacter pylori infection in Mexico

A nationwide community-based survey for Helicobacter pylori infection had not been done. This study sought to determine the seroprevalence of infection in Mexico, and the socioeconomic and demographic variables that are risk factors for infection. The survey assessed 11,605 sera from a sample population representing persons ages 1-90 years from all socioeconomic and demographic levels and from all regions of Mexico. Antibodies against H. pylori were studied by ELISA using whole cell antigen. Among the findings were that 66% of the population was infected and that age was the strongest risk factor for infection. By age 1 year, 20% were infected and by age 10 years, 50% were infected. Crowding (odds ratio [OR], 1.4), low educational level (OR, 2.42), and low socioeconomic level (OR, 1.43) were risk factors for infection. Prevalence was similar in urban and in rural communities (OR, 0.95). This study is the largest community-based seroepidemiologic study of H. pylori to date.

[Molecular epidemiology in the epidemiological transition]

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.

Cigarette smoking; knowledge and attitudes among Mexican physicians

OBJECTIVE

To determine the prevalence of the smoking habit among Mexican physicians as well as some of their attitudes and information on specific issues concerning smoking.

MATERIAL AND METHODS

In 1993, a survey was carried out among 3,568 physicians of the three major official health care institutions in Mexico City. A questionnaire designed for The Mexican National Survey of Addictions (ENA 1993) was used. Prevalence of cigarette smoking, age of onset, number of cigarettes per day; also information and attitudes concerning smoking were assessed.

RESULTS

The mean age was 37, 66% were males. Of the 3,488 (98%) surveyed, 26.9% were smokers (62% daily), 20.6% were ex-smokers and 52.5% non-smokers. There were differences related to age and sex (p < 0.05). Of daily smokers, 36% smoked between 1 and 5 cigarettes. There was a significant trend among ex-smokers that linked the time they had ceased smoking with the fear to start smoking again. Physicians were well informed of the relationship between cigarette smoking and lung cancer. Over 80% considered tobacco an addictive drug but only 65% were in favor of banning smoking from their workplaces and over 10% were not aware that it is forbidden to smoke inside health care facilities.

CONCLUSIONS

These results differ from other studies that find the prevalence of smoking among physicians lower than in the general population. Our study revealed a greater prevalence of the smoking habit among female physicians and the number of cigarettes smoked per day was greater than in the general population regardless of sex.

First record in America of Aedes albopictus naturally infected with dengue virus during the 1995 outbreak at Reynosa, Mexico

Mosquito collections were conducted during a dengue outbreak in Reynosa, Tamaulipas, Mexico, July-December 1995. A total of 6694 adult mosquitoes (four genera and nine species) were captured, of which 2986 (78.3% females and 21.7% males) were Aedes albopictus and 2339 (39.7% females and 60.3% males) were Ae.aegypti. These two species comprised 84.2% of the total collection. Specimens were grouped into pools, nearly 50% of them processed for detection of virus by cythopathic effect in C6-36 and VERO cell cultures and by haemagglutination test. Five pools gave positive haemagglutination reactions and were examined by immunofluorescence using monoclonal antibodies to flavivirus and to dengue virus. One pool of ten Ae.albopictus males was positive for dengue virus: serotypes 2 and 3 were identified by serotype-specific monoclonal antibodies and confirmed by RT-PCR. This is the first report of Ae.albopictus naturally infected with dengue virus in America. Also, it is the very first time Ae.albopictus males have been found infected with dengue virus in the wild.

Higher milk intake during pregnancy is associated with lower maternal and umbilical cord lead levels in postpartum women

Lead exposure and its deleterious effects continue to be a problem in many countries. The lack of effective and safe treatments for low-level intoxication has promoted environmental interventions to control different sources of lead. In this study we evaluated the effect of milk consumption in 1849 mother-and-child pairs participating in the lead surveillance program in Mexico City. The mean lead levels were 11.2 micrograms/dL for maternal blood lead (MBL) and 10.8 micrograms/dL in umbilical cord. The correlation between blood lead and umbilical cord lead was r = 0.74. Forty-eight percent of the MBL exceeded 10 micrograms/dL and 9.5% exceeded 20 micrograms/dL. Maternal blood lead was positively related to the use of lead-glazed ceramic were and to traffic exposure and was inversely related to the consumption of milk and orange juice. Women who reported the consumption of more than 7 glasses of milk per week had a blood lead level of 8.7 micrograms/dL; in comparison, those women who reported a consumption of less than 7 glasses per week had a blood lead level of 11.1 micrograms/dL. Similar findings were observed for lead measured in umbilical cord. The association between lead levels and milk intake remained unchanged after taking in consideration other predictors of blood lead. This study suggests that a simple intervention could reduce lead burden among women and their newborns.

[Consumption of prescription drugs in 60-65 years old population in Mexico. National Survey on Addictions, 1993]

OBJECTIVE

To estimate the prevalence of consumption of medical drugs among the population 60 to 65 years old identified in the National Survey on Addictions 1993 and obtain data on the demographic characteristics of these consumers.

MATERIAL AND METHODS

A cross-sectional, probabilistic, stratified and cluster sample of subjects between 12 and 65 years old living in urban areas of the country was selected.

RESULTS

Of the 911 elderly subjects identified, 218 (23.9%) were consumers of prescription drugs, constituting 17% of men and 28% of women. The most frequently used drugs were central nervous system depressants (22% of women and 13% of men) followed by opiates (7% of women and 5% of men). The onset age of consumption was 60 years old and men started earlier than women. Of prescription drug users, 85% use depressors and opiates by prescription, 3% self-medicate themselves and 5% follow a friend's recommendation. Nine per cent use prescription drugs longer than the prescribed time.

CONCLUSIONS

More extensive, specific studies of drug consumption by the elderly should be carried out to explore prevalence of use, which are used most frequently, frequency of adverse effects, effects on quality of life and social support networks for the elderly, among other topics.

[Chronic diseases in persons of 60-69 years of age]

OBJECTIVE

The results of the National Survey of Chronic Diseases (Mexico, 1993) regarding the prevalence of hypertension, diabetes mellitus and obesity in the 60 to 69 years old group are presented on a national and regional level.

MATERIAL AND METHODS

Measurements taken included weight, height, blood pressure, visual acuity, glycosylated hemoglobin, cholesterol, lipoproteins, insulin, triglycerides and albumin. Data analysis were performed using the statistical package SPSS to carry out Mantel-Haenszel and chi square tests.

RESULTS

Analysis of data for 1239 individuals showed that 38% of the aging population have hypertension. 25% are obese and 21% have diabetes. Findings showed that 28% of the individuals with hypertension and 18% of those with diabetes were detected through the survey. Obesity was strongly associated with hypertension and 33% of cases were not under treatment. Differences on the regional level are presented and results are discussed by sex and risk factors. The risk of diabetes was higher in those with other family members with diabetes, while microalbuminuria and hypercholesterolemia were associated with diabetes in this population.

CONCLUSIONS

The results of the study support the need to improve early detection programs and intensify those interventions that prevent early mortality due to these particular diseases.

Impact of oral rehydration and selected public health interventions on reduction of mortality from childhood diarrhoeal diseases in Mexico

Reported are the results of an analysis of mortality trends from diarrhoeal diseases among under-5-year-olds in Mexico between 1978 and 1993 in relation to the impact of education, basic sanitation, and selected medical care practices. The study period was divided into three stages; the first pre-dated the widespread application of oral rehydration therapy (ORT); the second, covered the implementation of a nationwide programme promoting ORT; and the third included additional measures, such as immunization and improvements in basic sanitation. Mortality rates decreased progressively, at an average of 1.8% per year in the first stage, 6.4% in the second, and 17.8% in the third. The importance of literacy campaigns for women and the promotion of ORT was confirmed. Both of these measures reduced mortality; however, a greater reduction resulted from a massive immunization campaign against measles and improvements in sanitation (expansion of the drainage and piped water systems, improved water chlorination procedure, and effective prohibition of the use of sanitary sewage for vegetable irrigation).

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.

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.

[Factors related to drug use by adolescents in urban areas of Mexico]

This is a retrospective study on teenagers from 14 to 17 years of age based on data from the National Survey on Drug Addiction conducted in 1988. The aim of this study was to discover the factors linked to drug consumption among Mexican urban teenagers. This paper reports prevalence rates (PR), raw and adjusted by gender as well as Cornfield's intervals (CI) of 95 per cent. For women, factors linked to drug use were: alcohol consumption (PR6.5, CI:1.5-28.3); father drug user (PR 3.2, CI:1.1-9.5). For men, factors linked to drug use were: age (PR 3.2; CI: 1.5-7.4); non religious practice (PR 2.7, CI: 1.2-6.4); acquaintances who are users of marihuana, cocaine or heroine-opium (PR 12.2, 6.6 and 7.0 respectively); and if the father, a brother or another relative are drug users (PR 4.1, 7.1 and 3.5 respectively). These findings show important gender differences in drug consumption patterns and linked factors. This paper brings out useful information for a complete understanding of this problem in Mexico.

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.

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.

[The management of diarrheal disease at home in some regions of Mexico]

A survey was carried out between May and October, 1991 in eleven federal entities to know the correct household diarrhea case management (EMECADI). It was observed that among the 15,125 children less than five years old the punctual prevalence was of 6.4% (970 children); the incidence in the previous two weeks was 14.5% (1,605 children) and the annual incidence of diarrhea was 4.5 episodes per child per year. Among the children who presented diarrhea in the 24 hours, the following rates were observed: use of oral hydration solution, 17.1%; use of recommended homemade fluids, 63.2%; oral hydration therapy use, 63.2%; increased fluids, 29.9%; correct oral serum preparation, 60.0%; continued breast-feeding, 75.0%; continued feeding, 59.8%; adequate knowledge about seeking care, 12.5%, and drugs use, 53.2%. The reference and nutritional components should improved.

Alcohol consumption, low birth weight, and preterm delivery in the National Addiction Survey (Mexico)

In 1988 the Mexican General Directorate of Epidemiology and the Mexican Institute of Psychiatry carried out the first National Addiction Survey that provided prevalence estimates at national and regional levels of alcohol consumption, tobacco smoking, and several other drugs use. In addition, a questionnaire included questions regarding alcohol consumption during pregnancy and adverse outcomes. According to the results of logistic regression, women classified as suffering from Alcohol Dependence Syndrome had a very high risk of low birth weight and/or preterm delivery: Odds ratio = 12.1 with a 95% confidence interval of (1.3, 108.9) and p = .026. After controlling for several confounding variables, the findings remained basically the same.

[Direct costs of the treatment of AIDS in Mexico]

This report presents the results of a study of direct treatment costs of AIDS in Mexico, carried out in five public hospitals, four social security hospitals and one private hospital. The study included: a retrospective phase, a prospective phase and a longitudinal followup. The study found that the average AIDS patient has a total of two hospital admissions per year, with an average stay of 20 days per admission, and an annual cost of almost $4,043 US. The hospital admission costs per patient ranged between $1,430 US and $7,350 US with an average cost of $2,565 US. The outpatient's treatment costs per year were of $300 US. The patient's expenses at their homes were $1,100 US. We conclude that treatment costs for AIDS patients, excluding use of AZT, are higher than the treatment costs of comparable diseases. The greatest cost is that for inpatient care; thus, we recommend improving outpatient care services in order to provide more comprehensive care to patients and their families.

[Methodology of the National Seroepidemiologic Survey, Mexico]

This paper briefly describes the methodology employed in the National Seroepidemiologic Survey (NSS). Among the aspects discussed are: previous studies of this kind; the master sampling frame; the sample design, the study population and sample size; the selection of diseases for study; the variables; instruments for data collection; operational design for the survey; as well as data processing and analysis. The overall response rate of the NSS was 78.4 per cent of the surveyed homes, 40 per cent of which were from rural areas (communities of less than 2,500 persons). The non-response rate was 41.3 per cent with the highest level in Baja California Sur (RNR = 26%) and the lowest in Puebla (RNR = 50.9%). The poor response in Puebla may have been due to the fact that it was the first state surveyed and served as the pilot project. The variable estimates from the NSS were similar to those found in other national surveys and the General Population Census. Therefore, these is reason to believe that the results of the NSS were representative and comparable. The final part of the paper describes the NSS projects already published, national seroprevalences, considerations concerning inference, and the laboratory procedures utilized in each project.

[Seroepidemiology of brucellosis in Mexico]

Brucellosis is an important and widely distributed zoonosis in Mexican cattle which also affects an unknown proportion of the human population. This report presents the brucellosis antibody levels registered in the National Seroepidemiology Survey (NAS) in sera obtained from 66,982 healthy persons from one to 98 years of age and determined by the test of plaque microagglutination. Seroprevalences by states ranged from 0.24 per cent in Morelos to 13.5 per cent in the state of Mexico. The national mean was estimated to be 3.42 per cent. The analysis showed no statistical differences for brucellosis antibody levels by urban and rural residence and by density of family sleeping areas (three or more persons vs. one or two persons per bedroom). Adults between 20 and 39 years of age had greater seropositivity and children from one to nine years had the least. Women were most affected and had 48 per cent more seropositivity than men. According to the information obtained in the study, brucellosis in Mexico has the following characteristics: it is related to gender but not to occupation; affects persons in all age groups, social strata and is independent of size of the community of residence. Historically, brucellosis has been an endemic disease in Mexico. Recently an increasing incidence has been reported, and this is possibly due to a better national notification system.