A GENETIC MARKER STUDY OF NON - INSULIN DEPENDENT DIABETICS IN THE MEXICAN-AMERICAN COMMUNITY FROM STARR COUNTY, TEXAS (PLASMA GLUCOSE, HEMOGLOBIN ANALYSIS)

Diabetes mellitus occurs in two forms, insulin-dependent (IDDM, formerly called juvenile type) and non-insulin dependent (NIDDM, formerly called adult type). Prevalence figures from around the world for NIDDM, show that all societies and all races are affected; although uncommon in some populations (.4%), it is common (10%) or very common (40%) in others (Tables 1 and 2).^ In Mexican-Americans in particular, the prevalence rates (7-10%) are intermediate to those in Caucasians (1-2%) and Amerindians (35%). Information about the distribution of the disease and identification of high risk groups for developing glucose intolerance or its vascular manifestations by the study of genetic markers will help to clarify and solve some of the problems from the public health and the genetic point of view.^ This research was designed to examine two general areas in relation to NIDDM. The first aims to determine the prevalence of polymorphic genetic markers in two groups distinguished by the presence or absence of diabetes and to observe if there are any genetic marker-disease association (univariate analysis using two by two tables and logistic regression to study the individual and joint effects of the different variables). The second deals with the effect of genetic differences on the variation in fasting plasma glucose and percent glycosylated hemoglobin (HbAl) (analysis of Covariance for each marker, using age and sex as covariates).^ The results from the first analysis were not statistically significant at the corrected p value of 0.003 given the number of tests that were performed. From the analysis of covariance of all the markers studied, only Duffy and Phosphoglucomutase were statistically significant but poor predictors, given that the amount they explain in terms of variation in glycosylated hemoglobin is very small.^ Trying to determine the polygenic component of chronic disease is not an easy task. This study confirms the fact that a larger and random or representative sample is needed to be able to detect differences in the prevalence of a marker for association studies and in the genetic contribution to the variation in glucose and glycosylated hemoglobin. The importance that ethnic homogeneity in the groups studied and standardization in the methodology will have on the results has been stressed. ^

A COMPARISON OF COUNTY HOSPITAL UTILIZATION BEFORE AND AFTER INTERVENTION BY THE HOSPITAL'S ALCOHOLISM SERVICES PROGRAM

This study examines the reduction in hospital utilization of 393 public hospital patients who were referred to the hospital's alcoholism screening program for intervention. The 393 patients were the total patient population of the alcoholism screening program for the period of September through December, 1982. Medical records of these patients were investigated to assess the total number of hospital days six months before and six months after intervention. The findings support the hypothesis of decreased utilization. The total number of hospital days for 393 patients before intervention of the alcoholism program was 3,458, with a mean length of stay of 8.80 days. The total number of hospital days after intervention was 458 days, with a mean length of stay of 6.50 days. The average individual difference (decrease) was 7.63 days for one year. From a total of 393 patients counseled by the alcoholism program, 106 (27%) went to treatment for their alcoholism. Other aims were to examine the referral sources (physicians, nurses, social workers and the MAST); study the impact of familial history of alcoholism on referrals, and explore the MAST scores of patients successfully referred. Implications of the study are that it would benefit the public hospital, with their disproportionate numbers of alcoholics, to intervene in the behavioral patterns of alcoholism. Such intervention would be a factor in reducing the overall hospitalization of the alcoholic. ^

INFANT MORTALITY IN THE MEXICAN AMERICAN COMMUNITY: AN ANALYSIS OF DIFFERENTIALS IN INFANT, NEONATAL, AND POSTNEONATAL MORTALITY BY ETHNICITY AND PARENTAL NATIVITY, 1974-75 SINGLE LIVE BIRTH COHORT, HARRIS COUNTY, TEXAS

The paradoxically low infant mortality rates for Mexican Americans in Texas have been attributed to inaccuracies in vital registration and idiosyncracies in Mexican migration in rural areas along the U.S.-Mexico border. This study examined infant (IMR), neonatal (NMR), and postneonatal (PNMR) mortality rates of Mexican Americans in an urban, non-border setting, using linked birth and death records of the 1974-75 single live birth cohort (N = 68,584) in Harris County, Texas, which includes the city of Houston and is reported to have nearly complete birth and death registration. The use of parental nativity with the traditional Spanish surname criterion made it possible to distinguish infants of Mexican-born immigrants from those of Blacks, Anglos, other Hispanics, and later-generation, more Anglicized Mexican Americans. Mortality rates were analyzed by ethnicity, parental nativity, and cause of death, with respect to birth weight, birth order, maternal age, legitimacy status, and time of first prenatal care.^ While overall IMRs showed Spanish surname rates slightly higher than Anglo rates, infants of Mexican-born immigrants had much lower NMRs than did Anglos, even for moderately low birth weight infants. However, among infants under 1500 grams, presumably unable to be discharged home in the neonatal period, Mexican Americans had the highest NMR. The inconsistency suggested unreported deaths for Mexican American low birth weight infants after hospital discharge. The PNMR of infants of Mexican immigrants was also lower than for Anglos, and the usual mortality differentials were reversed: high-risk categories of high birth order, high maternal age, and late/no prenatal care had the lowest PNMRs. Since these groups' characteristics are congruent with those of low-income migrants, the data suggested the possibility of migration losses. Cause of death analysis suggested that prematurity and birth injuries are greater problems than heretofore recognized among Mexican Americans, and that home births and "shoebox burials" may be unrecorded even in an urban setting.^ Caution is advised in the interpretation of infant mortality rates for a Spanish surname population of Mexican origin, even in an urban, non-border area with reportedly excellent birth and death registration. ^

ENVIRONMENTAL EXPOSURES AND LUNG CANCER RISK AMONG WOMEN IN HARRIS COUNTY, TEXAS, 1977-1980 (OCCUPATION, SMOKING, BYSTANDER)

Excessively high, accelerating lung cancer rates among women in Harris County, Texas, prompted this case-comparison study. Objectives were to compare patterns of employment, indirect exposures, and sociodemographic variables of lung cancer cases with comparison subjects (compeers) after standardizing for possible confounders, such as age and cigarette smoking. Lung cancer cases were microscopically confirmed, white, Harris County residents. Compeers, chosen from Medicare records and Texas Department of Public Safety records, were matched on gender, race, age, resident and vital status. Personal interviews were conducted with study subjects or next-of-kin. Industries and occupations were categorized as high risk, based on previous studies.^ Almost all cases (95.0%) and 60.0% of compeers smoked cigarettes. The odds ratio for lung cancer and smoking is 13.9. Stopping smoking between ages 30-50 years carries a lower risk than stopping at age 58 or more years. Women's employment in a high risk industry or occupation results in consistently elevated, smoking-adjusted odds ratios. Frequency and duration of employment demonstrate a moderate dose-response effect. A temporal association exists with employment in a high risk occupation during 1940-1949.^ No increased risk appeared with passive smoking. Husband's employment in a construction industry or a structural occupation significantly increased the smoking-adjusted odds ratios among cases and compeers (O.R. = 2.9, 2.2). Smoking-adjusted odds ratios increased significantly when women had resided with persons employed in cement (O.R. = 3.2) or insulation (O.R. = 5.5) manufacturing, or a high rise construction industry (O.R. = 2.4). A family history of lung cancer resulted in a two-fold increase in smoking-adjusted odds ratios. Vital status of compeers affected the odds ratios.^ Work-related exposures appear to increase the risk of lung cancer in women although cigarette smoking has the single highest odds ratio. Indirect exposure to certain employment also plays a significant role in lung cancer in women. Investigations of specific direct and indirect hazardous exposures in the workplace and home are needed. Cigarette smoking is as hazardous for women as for men. Smoking should be prevented and eliminated. ^

Spatial analysis of pertussis cases in Harris County from 2005-2010

Objective: This study examined the recent trends and characteristics of reported pertussis in Harris County from 2005-2010. ^ Methods: The study population included surveillance data from all reported pertussis cases from January 1, 2005 to December 31, 2010 to Harris County Public Health and Environmental Services (HCPHES). We calculated incidence and attack rates for varying age groups, race/ethnicity, and gender. Spatial analyses were conducted of hot spot and cluster of incident cases in Harris County census tracts. Maps were constructed using geographic information system. ^ Results: Age-specific incidence rates of reported cases of pertussis were highest among infants under a year of age and lowest among adults age 20 and older. Hispanics represented the most cases reported compared to any other race or ethnic group (42% of 483 cases). Age-adjusted rates were highest in 2009 at 9.81 cases per 100,000 population. Only 31.2% of people received at least four of the recommended five doses of vaccine. Spatial analyses revealed statistically significant clusters within the northeast region of Harris County. ^ Conclusions: Hispanic infants are the most at risk group for pertussis. Although 70% of cases had a history of immunization, 41.8% of infants were appropriately vaccinated for their age. Increased vaccination coverage may decrease the incidence of pertussis.^

A screening for anti-West Nile immunoglobulin-G and immunoglobulin-M in the Cameron County Hispanic cohort

This study is designed to be a cross-sectional, retrospective analysis of the seroprevalence of anti-WNV antibodies in 1,006 plasma samples collected from February 2, 2006 to June 18, 2007 originally for The Cameron County Hispanic Cohort: Extreme obesity and uncontrolled diabetes on the U.S.-Mexico border, major concerns for populations with health disparities. The aim of this thesis research is to give a more up-to-date picture of Flavivirus activity in south Texas, which can potentially contribute to the surveillance objective of arboviral control in this area. A West Nile virus (WNV) seroprevalence study in humans in this particular area has never before been completed. Plasma samples were tested using immunoglobulin-G (IgG) and immunoglobulin-M (IgM) WNV enzyme linked immunosorbent assays (ELISA). Estimated seroprevalence for this particular population was 0.98% or 9.8 cases of West Nile disease per 1,000 citizens. After IgG testing, seroprevalence in the study population was found to be 15.4%. Specimens tested for WNV IgG were compared with a subset of specimens (N=803) tested for history of primary dengue virus (DENV) infection. Of the 803 specimens tested for IgG to DENV, 308 were positive. Of the 132 positive WNV IgG specimens in the subset, 131 (99.2%) tested also tested positive for DENV IgG. It would be helpful to use standard plaque reduction neutralization testing to determine if the seroprevalence is in fact lower because of cross-reaction to DENV on testing. Regardless of the possibility of other Flavivirus activity occurring prior to the introduction of WNV into the United States and the potential for cross-reactivity, Texas has ranked in the top 5 states with the highest, laboratory confirmed incidence of infection with WNV since 2003. Indicating that climate factors and the presence of suitable vectors makes Texas a hotspot for WNV activity. ^ A description of the study population by age, gender, and income was done indicating a statistically significant income difference with a mean household income per year being $13,413.55 for a case and $20,268.80 for non-cases (p=0.001). Lower income neighborhoods should be targeted for education and prevention of vector-borne diseases during the summer months in Cameron County. With respect to gender, being male has been noted in the literature to be a risk factor for infection with WNV (25). In this study, females comprised approximately 68% of the study population, they also made up 66.5% of the positive IgG specimens. An odds ratio of 0.91 indicates that women are less likely to be IgG positive for WNV as compared to men; however, this was not found to be significant based on the 95% confidence interval, but is consistent with the literature. When looking at age difference between positive and negative/equivocal cases, there was no statistical difference found between the two groups. ^ We concluded that this study will enable us to understand the epidemiology of WNV transmission since its introduction into the United States and hopefully to maintain or improve the current measures we have in place to prevent infections that are seen annually with WNV.^

Burden of invasive pneumococcal disease in Harris County, Texas (2003--2010) and the implication for enhanced public health surveillance of isolates

Invasive pneumococcal disease (IPD) causes significant health burden in the US, is responsible for the majority of bacterial meningitis, and causes more deaths than any other vaccine preventable bacterial disease in the US. The estimated National IPD rate is 14.3 cases per 100,000 population with a case-fatality rate of 1.5 cases per 100,000 population. Although cases of IPD are routinely reported to the local health department in Harris County Texas, the incidence (IR) and case-fatality (CFR) rates have not been reported. Additionally, it is important to know which serotypes of S. pneumoniae are circulating in Harris County Texas and to determine if ‘replacement disease’ is occurring. ^ This study reported incidence and case-fatality rates from 2003 to 2009, and described the trends in IPD, including the IPD serotypes circulating in Harris County Texas during the study period, particularly in 2008 and 2010. Annual incidence rates were calculated and reported for 2003 to 2009, using complete surveillance-year data. ^ Geographic information system (GIS) software was used to create a series of maps of the data reported during the study period. Cluster and outlier analysis and hot spot analysis were conducted using both case counts by census tract and disease rate by census tract. ^ IPD age- and race-adjusted IR for Harris County Texas and their 95% confidence intervals (CIs) were 1.40 (95% CI 1.0, 1.8), 1.71 (95% CI 1.24, 2.17), 3.13 (95% CI 2.48, 3.78), 3.08 (95% CI 2.43, 3.74), 5.61 (95% CI 4.79, 6.43), 8.11 (95% CI 7.11, 9.1), and 7.65 (95% CI 6.69, 8.61) for the years 2003 to 2009, respectively (rates were age- and race-adjusted to each year's midyear US population estimates). A Poisson regression model demonstrated a statistically significant increasing trend of about 32 percent per year in the IPD rates over the course of the study period. IPD age- and race-adjusted case-fatality rates (CFR) for Harris County Texas were also calculated and reported. A Poisson regression model demonstrated a statistically significant increasing trend of about 26 percent per year in the IPD case-fatality rates from 2003 through 2009. A logistic regression model associated the risk of dying from IPD to alcohol abuse (OR 4.69, 95% CI 2.57, 8.56) and to meningitis (OR 2.42, 95% CI 1.46, 4.03). ^ The prevalence of non-vaccine serotypes (NVT) among IPD cases with serotyped isolates was 98.2 percent. In 2008, the year with the sample more geographically representative of all areas of Harris County Texas, the prevalence was 96 percent. Given these findings, it is reasonable to conclude that ‘replacement disease’ is occurring in Harris County Texas, meaning that, the majority of IPD is caused by serotypes not included in the PCV7 vaccine. Also in conclusion, IPD rates increased during the study period in Harris County Texas.^

A comparison of two statistical methods for analysis of day of the week effect on births from 2005-2007 in Harris County of Texas

The pattern of the births during the week has been reported by many studies. The births occurred in weekends are found consistently less then births occurred in weekdays. This study employed two statistical methods, two-way ANOVA and two-way Friedman's test to analyse the daily variations in amount of births of 222,735 births from 2005-2007 in Harris County, Texas. The two methods were compared on their assumptions, procedures and results. Both of the tests showed a significant result which indicated that the births through the week are not uniformly distributed. The result of multiple comparison demonstrated the births occurring on weekends were significantly different than the births occurring on weekdays with least amount on Sundays.^

Spatial analysis of cardiovascular disease mortality and air pollution in Harris County, Texas

The association between fine particulate matter air pollution (PM2.5) and cardiovascular disease (CVD) mortality was spatially analyzed for Harris County, Texas, at the census tract level. The objective was to assess how increased PM2.5 exposure related to CVD mortality in this area while controlling for race, income, education, and age. An estimated exposure raster was created for Harris County using Kriging to estimate the PM2.5 exposure at the census tract level. The PM2.5 exposure and the CVD mortality rates were analyzed in an Ordinary Least Squares (OLS) regression model and the residuals were subsequently assessed for spatial autocorrelation. Race, median household income, and age were all found to be significant (p<0.05) predictors in the model. This study found that for every one μg/m3 increase in PM2.5 exposure, holding age and education variables constant, an increase of 16.57 CVD deaths per 100,000 would be predicted for increased minimum exposure values and an increase of 14.47 CVD deaths per 100,000 would be predicted for increased maximum exposure values. This finding supports previous studies associating PM2.5 exposure with CVD mortality. This study further identified the areas of greatest PM2.5 exposure in Harris County as being the geographical locations of populations with the highest risk of CVD (i.e., predominantly older, low-income populations with a predominance of African Americans). The magnitude of the effect of PM2.5 exposure on CVD mortality rates in the study region indicates a need for further community-level studies in Harris County, and suggests that reducing excess PM2.5 exposure would reduce CVD mortality.^