Prevalence and trends of substance abuse in Harris County, Texas, 1989 to 1991

In the late 1980s, Harris County, Texas began experiencing an escalation of drug-related activities. Various indicators used in this analysis tracked drug-related trends from 1989 to 1991 to determine patterns for comparison of local (Houston/Harris County, Texas) to national levels.^ An important indicator of the drug scenario was drug-related activities among youths, which increased during the period of this study. The Harris County Juvenile Probation Department showed that among arrests for drug-related activities, felonies increased from 25% in 1988 to 53% in 1991. With the rise in drug-related crimes, and substance abuse among the student body, school districts were forced to institute drug education programs in an effort to curtail such activities.^ Law enforcement agencies in the county saw increased demands for their services as a result of drug activities. Harris County Sheriffs Department reported a 32% plus increase in drug-related charges between 1986 and 1991. Houston Police Department reported an increase of 109% for the same period.^ Data from the Harris County Medical Examiner, the National Institute of Justice's Drug Use Forecasting System (Houston), and drug treatment facilities around Houston/Harris County, Texas indicated similar drug usage trends. Over a four-year period (1988-91), the drugs most frequently detected during blood and urine analyses were cocaine, followed by marijuana, heroin, LSD, and methamphetamines.^ From 1988 to 1991, most drug rehabilitation organizations experienced increased demands for their services by approximately 35%. Several other organizations experienced as much as a 70 percent increase. Males accounted for roughly 70% and females about 30% of persons seeking treatment. However, the number of females pursuing treatment increased, thereby reducing the gender gap.^ Blacks in Houston/Harris County were at higher risk for drug usage among the general population, but sought treatment more readily than other ethnic groups. Whites sought treatment in similar numbers as Blacks, but overall the risk appeared smaller because they made up a larger portion of the Houston/Harris County population.^ This analysis concluded that drug trends for the Houston/Harris County, Texas did not follow national trends, but showed patterns of its own. It was recommended that other communities carry out similar studies to determine drug use trends particular to their local. ^

Ethnicity as a risk factor for diabetes incidence in a population of diagnosed hypertensives

Significant racial/ethnic differences exist in prevalence of hypertension (HTN) and non-insulin dependent diabetes mellitus (NIDDM). Hypertension is more common in diabetics than in non-diabetics, and an etiologic link between the two conditions has been proposed. Since there are few longitudinal studies of persons with both HTN and NIDDM, a retrospective cohort study was conducted to determine if ethnicity (Black, Hispanic (Mexican-American), and non-Hispanic White) was related to NIDDM incidence in a low-SES, multi-ethnic clinic population of diagnosed hypertensives. Two thousand nine hundred forty-one hypertensives free of NIDDM at baseline were followed for up to 10 years. Mean baseline age was 56 $\pm$ 12 years, M:F percent was 33:67, and Black:Hispanic:White percent was 63:17:20. There were 236 incident cases of NIDDM. In Cox proportional hazards analysis, the risk of developing NIDDM over 10 years was not related to ethnicity after controlling for significant covariates, including age, baseline blood glucose and body mass index (adjusted RR for Blacks compared to Whites =.82, 95 percent CI =.57-1.18; adjusted RR for Hispanics compared to Whites =.84, 95 percent CI =.51-1.38). This result contrasts with the increased risk of NIDDM among Blacks and Hispanics compared to Whites found in the general population. The study suggests that a diagnosis of hypertension equalizes the risk of developing NIDDM among the three ethnic groups. ^

Behavioral risk profile of marathon runners

Although long distance running clearly has benefits--as witnessed by its popularity--it also has risks of injury and death. Little is known, however, about the prevalence of potentially dangerous training habits in long distance runners, although anecdotal information suggests that many runners have erroneous beliefs about risks and benefits of marathon running. We conducted a cross-sectional survey to estimate the prevalence of 19 potentially dangerous training habits (risky behaviors) among marathon runners. A 66-item self-administered questionnaire was mailed to a stratified random sample of runners who finished of the 1992 Houston-Tenneco Marathon and were 21-71 years of age. Responses were obtained from 508 runners (83%) with approximately equal representation in four age-gender groups: men $<$40 years, men $\ge$40 years, women $<$40 years, and women $\ge$40 years.^ Prevalences of risky behaviors were high. 50% or more ran in dangerously hot and humid conditions, did not cool down or stretch after running, did not wear proper running gear, or ran when injured or ill; 25-49% did not warm up, ran on dangerous surfaces, did not drink sufficient water during training, increased weekly mileage too quickly, and ran during lightning storms; 10-24% ran daily, ran in areas with high pollution, ran in the same direction as traffic, did hard runs frequently, ran more than 60 miles per week, or ran against the advice of a physician.^ Positive associations were found between the practice of risky behaviors and self-reported prevalence of musculoskeletal injuries, heat-related injuries, noncompliance with recommendations for preventive health examinations, and noncompliance with positive health habits.^ These results indicate that many marathon runners engage in training habits that may increase risk of substantial injury or illness. Further studies are needed to explore the association of risky training behaviors on the incidence of injuries, and to determine reasons for noncompliance with recommendations from sports medicine specialists. ^

The association between CD4+ lymphocyte count and measures of body composition in HIV-infected men

Purpose. This project was designed to describe the association between wasting and CD4 cell counts in HIV-infected men in order to better understand the role of wasting in progression of HIV infection.^ Methods. Baseline and prevalence data were collected from a cross-sectional survey of 278 HIV-infected men seen at the Houston Veterans Affairs Medical Center Special Medicine Clinic, from June 1, 1991 to January 1, 1994. A follow-up study was conducted among those at risk, to investigate the incidence of wasting and the association between wasting and low CD4 cell counts. Wasting was described by four methods. Z-scores for age-, sex-, and height-adjusted weight; sex-, and age-adjusted mid-arm muscle circumference (MAMC); and fat-free mass; and the ratio of extra-cellular mass (ECM) to body-cell mass (BCM) $>$ 1.20. FFM, ECM, and BCM were estimated from bioelectrical impedance analysis. MAMC was calculated from triceps skinfold and mid-arm circumference. The relationship between wasting and covariates was examined with logistic regression in the cross-sectional study, and with Poisson regression in the follow-up study. The association between death and wasting was examined with Cox's regression.^ Results. The prevalence of wasting ranged from 5% (weight and ECM:BCM) to almost 14% (MAMC and FFM) among the 278 men examined. The odds of wasting, associated with baseline CD4 cell count $<$200, was significant for each method but weight, and ranged from 4.6 to 12.7. Use of antiviral therapy was significantly protective of MAMC, FFM and ECM:BCM (OR $\approx$ 0.2), whereas the need for antibacterial therapy was a risk (OR 3.1, 95% CI 1.1-8.7). The average incidence of wasting ranged from 4 to 16 per 100 person-years among the approximately 145 men followed for 160 person-years. Low CD4 cell count seemed to increase the risk of wasting, but statistical significance was not reached. The effect of the small sample size on the power to detect a significant association should be considered. Wasting, by MAMC and FFM, was significantly associated with death, after adjusting for baseline serum albumin concentration and CD4 cell count.^ Conclusions. Wasting by MAMC and FFM were strongly associated with baseline CD4 cell counts in both the prevalence and incidence study and strong predictors of death. Of the two methods, MAMC is convenient, has available reference population data, may be the most appropriate for assessing the nutritional status of HIV-infected men. ^

Perceived risk and outcome expectancy on the practice of home infusion technique in a hemophilia population

This study described home infusion techniques and practices, measured the perceived risk of HIV and hepatitis transmission to self and others, and measured the outcome expectancy of following risk reduction guidelines for 90 hemophilia patients and/or their infusion assistants. It also assessed general knowledge of HIV and hepatitis information for the same population.^ The study subjects were hemophilia patients or their infusion assistants from the Gulf States Hemophilia Center in Houston, the El Paso Satellite Hemophilia Clinic in El Paso, or Texas members of the Women Outreach Network of the National Hemophilia Foundation (WONN) group. Each subject was interviewed either by telephone or in person. The questionnaire used was developed for the study and consisted of 60 items. These items assessed general demographics for the patients and assistants, including questions about their training to do infusions as well as the actual practices, measured perceived personal risk for the transmission of HIV or hepatitis to the assistants, perceived risk of transmission of HIV or hepatitis to others for assistants and self-infusers, and the outcome expectancy for following recommended risk reduction guidelines also for both groups.^ The theoretical framework used assumed that perceived risk and outcome expectancy would be predictive of behavior. The findings did not support this theory. Instead, the findings suggest that infusion behavior is habitual in nature; most respondents perform exactly the same behavior for every infusion. Since none of the variables selected were predictive of the compliance behavior for home infusion the teaching method should be directed towards mastery learning, or learning that will incorporate the correct behavior into a habitual pattern of home infusion. ^

A proposed application of the attributable risk technique in the assessment of unmet need among newly organized populations

In the midst of health care reform, and as health care organizations reorganize to provide more cost-effective healthcare, the population is being shifted into new healthcare delivery systems such as health insurance purchasing alliances, and health maintenance organizations. These new models of delivery are usually organized within resource restricted and data limited environments. Health care planners are faced with the challenge of identifying priorities for preventive and primary care services within these newly organized populations (Medicare HMO, Medicaid HMO, etc.). The author proposes a technique usually employed in epidemiology--attributable risk estimation--as a planning methodology to establish preventive health priorities within newly organized populations. Illustrations of the methodology are provided utilizing the Texas 1992 population. ^

An evaluation of a behavioral change intervention for smokeless tobacco use

During the last three decades considerable attention has been placed on the reduction of tobacco use due to cigarette smoking. During this time, studies have been funded and programs have been developed that focus on both prevention and cessation of cigarette smoking. This intense focus has led to a significant decline in cigarette smoking. But now, use of another form of tobacco--smokeless tobacco--is gaining in popularity.^ In 1989, the National Cancer Institute funded a research study at The University of Texas M. D. Anderson Cancer Center, called Working Well, to develop, implement, and evaluate worksite health promotion programs aimed at reducing cancer risks. As part of this program, a behavioral intervention for smokeless tobacco use was developed. This dissertation evaluates the impact of that behavioral change intervention for smokeless tobacco use.^ Data collected during the Working Well program were analyzed to determine the effect of the intervention. The primary outcomes analyzed were smokeless tobacco cessation, stages of change movement, and prevalence. The secondary outcomes analyzed included the prediction of smokeless tobacco use, stage movement, and cessation. Primary outcome analyses were conducted using the worksite as the unit of analysis, while the secondary analyses were conducted using the individual as the unit of analysis.^ Approximately 20% of the male population used smokeless tobacco. Results of intervention analyses indicate that the Working Well program produced no intervention effect on any of the primary outcomes. At the final observation, the experimental worksites achieved a quit rate of 27%, while the control worksites achieved a quit rate of 26% (P = 0.78). Stage movement for the experimental worksites was 49%, while the control worksites experienced stage movement of 43% (P = 0.20). The results of the analyses on smokeless tobacco prevalence followed the same pattern. Predictors of smokeless tobacco use, cessation, and stage movement were also identified.^ Based on the results found in this study, smokeless tobacco should remain a research priority. Future research should focus on smokeless tobacco use, including the identification of the determinants of smokeless tobacco use and the development of measures and effective intervention strategies. ^

Adult weight gain and risk of colon cancer in men

Previous research supports the hypothesis that a "rich" diet (i.e., high in fat and low in fiber) increases the risk of colon cancer. Previous research also supports the hypothesis that physical inactivity increases the risk of colon cancer, perhaps because physical inactivity decreases gut motility, thereby increasing tee time that carcinogens are in contact with the intestinal mucosa. Habitual physical inactivity, combined with rich diet, ordinarily results in chronic energy imbalance and gain in weight, except when energy balance is modified by disease or factors such as cigarette smoking. Cigarette smokers typically stay lean because of effects of smoking on the resting metabolic rate as well as on efficiency of caloric intake and storage. Therefore, if physical inactivity and rich diet do increase the risk of colon cancer, then weight gain during young adulthood should be positively associated with incidence of colon cancer during later life, especially in nonsmokers.^ This hypothesis was investigated in a cohort of 2,059 randomly selected middle-aged men who were employed at the Western Electric Company in Chicago and were free of clinically diagnosed cancer at initial examination in 1958. Body mass index (BMI) in middle age was calculated from measured height and weight at the initial examination. BMI at age 20 was estimated from weight at age 20 as recalled at the initial examination and height as measured at the initial examination. Change in BMI between age 20 and middle age was estimated by subtracting the BMI at 20 from the BMI in middle age. Forty-nine incident cases of colon cancer were detected during 25 years (43,326 person-years) at risk. When stratified by level of change in BMI from age 20 to middle age ($\le$1.9, 2.0-3.9, 4.0-5.9, $\ge$6.0 kg/m$\sp2$), age-adjusted relative hazards of colon cancer in never-smokers were 1.00, 1.22, 2.31, and 5.01, respectively (p for trend = 0.008); corresponding values in ever-smokers were 1.00, 0.95, 0.77, and 0.87, These associations did not change appreciably after further adjustment for BMI at age 20, subscapular-triceps skinfold ratio, cigarette smoking, consumption of alcohol, energy, fat, and calcium.^ We also investigated the hypothesis that the risk of colon cancer was higher in men who were lean at age 20 and became fat by middle age (lean-to-fat) than in men who were fat at age 20 and stayed fat in middle-age (fat-to-fat). "Lean" was defined as BMI $<$24 kg/m$\sp2$ at age 20 and as BMI $<$27.0 kg/m$\sp2$ in middle age. Among never-smokers, in comparison to men who were lean at age 20 and in middle age (lean-to-lean), the age-adjusted relative hazard of colon cancer was 1.43 in the fat-to-fat group (95% confidence interval (CI) 0.37-5.52) and 3.36 in the lean-to-fat group (95% CI 1.21-9.37). This investigation provides new results on the magnitude of risk of colon cancer associated with weight gain during adulthood (from age 20 to middle age). This relation was obscured or underestimated in previous studies due to effect-modification by cigarette smoking. Finally, the result supports the idea that a life-style characterized by chronic energy imbalance during young adulthood increases risk of colon cancer. ^

Behavioral facets of cancer chemoprevention trials

Few studies have explored factors related to participation in cancer chemoprevention trials. The purpose of this dissertation was to conduct investigations in this emerging field by studying aspects of participation at three phases of cancer chemoprevention trials: at enrollment, during a placebo run-in period, and post-trial. In all three studies, subjects had a history of cancer and were at high risk of recurrence or second primary tumors.^ The first study explored correlates of enrollment in a head and neck cancer chemoprevention trial by comparing participants and eligible nonparticipants. Of 148 subjects who met the trial's preliminary eligibility criteria, 40% enrolled. In multivariate analysis, enrollment was positively associated with being male (OR 2.36) and being employed (OR 2.73). The most commonly cited reason for declining participation among nonparticipants was transportation.^ The second study examined outcomes of an eight-week placebo run-in period in a head and neck cancer chemoprevention trial. Of 391 subjects, 91.3% were randomized after the run-in. Adherence to drug capsules ranged from 0% to 120.3% (mean $\pm$ SD, 95.8% $\pm$ 15.1). In multivariate analysis, the main variable predicting run-in outcome was race; white subjects were 3.45 times more likely to be randomized than non-white subjects. Subjects with Karnofsky scores of 100 were 2.13 times more likely to be randomized than were subjects with lower scores.^ The third study used post-trial questionnaires to assess subjects' (n = 64) perceptions of participation in a cancer chemoprevention trial. The most highly rated trial benefit was the perception of potential colon cancer prevention, and the most troublesome barrier was erroneous billing for study visits. Perceived benefits were positively associated with interest in participating in future trials of the same (p = 0.05) and longer (p = 0.02) duration, and difficulty with trial pills and procedures was inversely related to interest in future placebo-controlled trials (p = 0.01).^ These are among the first behavioral studies to be completed in the rapidly growing field of cancer chemoprevention. Much work has yet to be done, however, to advance our understanding of the complex issues relating to chemoprevention trial participation. ^

Macular edema in Hispanics with non-insulin dependent diabetes mellitus in Starr County, Texas: Prevalence, incidence and risk factors

This project is based on secondary analyses of data collected in Starr County, Texas from 1981 till 1991 to determine the prevalence, incidence and risk factors for macular edema in Hispanics with non-insulin-dependent diabetes in Starr County, Texas. Two studies were conducted. The first study examined the prevalence of macular edema in this population. Of the 310 diabetics that were included in the study 22 had macular edema. Of these 22 individuals 9 had clinically significant macular edema. Fasting blood glucose was found to be significantly associated with macular edema. For each 10 mg/dl increase in fasting blood glucose there was a 1.07 probability of an increase in the risk of having macular edema. Individuals with fasting blood glucose $\ge$200 mg/dl were found to be more than three times at risk of having macular edema compared to those with fasting blood glucose $<$200 mg/dl.^ In the second study the incidence and the risk factors that could cause macular edema in this Hispanic population were examined. 240 Hispanics with non-insulin-dependent diabetes mellitus and without macular edema were followed for 1223 person-years. During the follow-up period 27 individuals developed macular edema (2.21/100 person-years). High fasting blood glucose and glycosylated hemoglobin were found to be strong and independent risk factors for macular edema. Participants taking insulin were 3.9 times more at risk of developing macular edema compared to those not taking insulin. Systolic blood pressure was significantly related to macular edema, where each 10 mmHg increase in systolic blood pressure was associated with a 1.3 increase in the risk of macular edema.^ In summary, this study suggests that hyperglycemia is the main underlying factor for retinal pathological changes in this diabetic population, and that macular edema probably is not the result of sudden change in the blood glucose level. It also determined that changes in blood pressure, particularly systolic blood pressure, could trigger the development of macular edema.^ Based on the prevalence reported in this study, it is estimated that 35,500 Hispanic diabetics in the US have macular edema. This imposes a major public health challenge particularly in areas with high concentration of Mexican Americans. It also highlights the importance of public health measures directed to Mexican Americans such as health education, improved access to medical care, and periodic and careful ophthalmologic examination by ophthalmologists knowledgeable and experienced in the management of diabetic macular edema. ^

THE INCIDENCE OF PELVIC ENDOMETRIOSIS IN ROCHESTER, MINNESOTA, 1970-1979

The primary objectives of the study were to measure the incidence of pelvic endometriosis among white females of reproductive age (15-49 years) in Rochester, Minnesota, during the period 1970-1979 and to determine the risk of endometriosis by age, marital status, nun status, and educational attainment in this population. An historical prospective design was used. Incident (newly diagnosed) cases were identified from community medical records, and person-years of risk in the study population were estimated from census data.^ Almost two-thirds of the incident cases had surgically verified endometriosis, while the remainder were diagnosed by clinical findings alone. Incidence rates were prepared first with histologically confirmed cases only and then with the successive inclusion of less certain cases: surgically visualized, clinically probable, and clinically possible. On this basis, overall incidence rates were 108.8 to 246.9 newly diagnosed cases per 100,000 person-years. The incidence of pelvic endometriosis was lowest for women 15-19 years of age, increased markedly through age 44, and then declined for women 45-49 years of age. A significantly greater risk of pelvic endometriosis in never married women was detected only when the numerator was limited to histologically confirmed cases. Among never married women 20-49 years of age, no significant difference in the risk of pelvic endometriosis by nun status was detected, but a trend toward a lower incidence in nuns was observed. Women with education beyond high school had a significantly higher incidence of endometriosis than women with less education.^ Cases in the four diagnostic groups differed greatly by age and marital status but were similar with respect to virtually all other characteristics, once age differences were considered. Reproductive history characteristics described included: age of menarche; history of menopause; total pregnancies; ages of first pregnancy, marriage, and sexual intercourse; years from menarche to first intercourse; years of ovulatory cycling; difficulty becoming pregnant; and delay of the first pregnancy by choice. How these characteristics of incident cases differ from those of women free of endometriosis needs to be studied in future research. ^

A QUANTITATIVE INVESTIGATION OF SOURCE AND ELEMENTAL COMPOSITION OF INDOOR AND OUTDOOR FINE PARTICULATE AIR POLLUTION IN HOUSTON (TEXAS)

An investigation was undertaken to determine the chemical characterization of inhalable particulate matter in the Houston area, with special emphasis on source identification and apportionment of outdoor and indoor atmospheric aerosols using multivariate statistical analyses.^ Fine (<2.5 (mu)m) particle aerosol samples were collected by means of dichotomous samplers at two fixed site (Clear Lake and Sunnyside) ambient monitoring stations and one mobile monitoring van in the Houston area during June-October 1981 as part of the Houston Asthma Study. The mobile van allowed particulate sampling to take place both inside and outside of twelve homes.^ The samples collected for 12-h sampling on a 7 AM-7 PM and 7 PM-7 AM (CDT) schedule were analyzed for mass, trace elements, and two anions. Mass was determined gravimetrically. An energy-dispersive X-ray fluorescence (XRF) spectrometer was used for determination of elemental composition. Ion chromatography (IC) was used to determine sulfate and nitrate.^ Average chemical compositions of fine aerosol at each site were presented. Sulfate was found to be the largest single component in the fine fraction mass, comprising approximately 30% of the fine mass outdoors and 12% indoors, respectively.^ Principal components analysis (PCA) was applied to identify sources of aerosols and to assess the role of meteorological factors on the variation in particulate samples. The results suggested that meteorological parameters were not associated with sources of aerosol samples collected at these Houston sites.^ Source factor contributions to fine mass were calculated using a combination of PCA and stepwise multivariate regression analysis. It was found that much of the total fine mass was apparently contributed by sulfate-related aerosols. The average contributions to the fine mass coming from the sulfate-related aerosols were 56% of the Houston outdoor ambient fine particulate matter and 26% of the indoor fine particulate matter.^ Characterization of indoor aerosol in residential environments was compared with the results for outdoor aerosols. It was suggested that much of the indoor aerosol may be due to outdoor sources, but there may be important contributions from common indoor sources in the home environment such as smoking and gas cooking. ^

ECONOMIC ANALYSIS OF THE DEMAND FOR PRESCRIPTION MEDICINE IN THE UNITED STATES

The purpose of this study was to understand the role of principle economic, sociodemographic and health status factors in determining the likelihood and volume of prescription drug use. Econometric demand regression models were developed for this purpose. Ten explanatory variables were examined: family income, coinsurance rate, age, sex, race, household head education level, size of family, health status, number of medical visits, and type of provider seen during medical visits. The economic factors (family income and coinsurance) were given special emphasis in this study.^ The National Medical Care Utilization and Expenditure Survey (NMCUES) was the data source. The sample represented the civilian, noninstitutionalized residents of the United States in 1980. The sample method used in the survey was a stratified four-stage, area probability design. The sample was comprised of 6,600 households (17,123 individuals). The weighted sample provided the population estimates used in the analysis. Five repeated interviews were conducted with each household. The household survey provided detailed information on the United States health status, pattern of health care utilization, charges for services received, and methods of payments for 1980.^ The study provided evidence that economic factors influenced the use of prescription drugs, but the use was not highly responsive to family income and coinsurance for the levels examined. The elasticities for family income ranged from -.0002 to -.013 and coinsurance ranged from -.174 to -.108. Income has a greater influence on the likelihood of prescription drug use, and coinsurance rates had an impact on the amount spent on prescription drugs. The coinsurance effect was not examined for the likelihood of drug use due to limitations in the measurement of coinsurance. Health status appeared to overwhelm any effects which may be attributed to family income or coinsurance. The likelihood of prescription drug use was highly dependent on visits to medical providers. The volume of prescription drug use was highly dependent on the health status, age, and whether or not the individual saw a general practitioner. ^

FEMALE SEXUAL MATURATION AND BLOOD PRESSURE (SECONDARY-SEX CHARACTERISTICS, GROWTH, DEVELOPMENT)

This study described the relationship of sexual maturation and blood pressure in a sample (n = 361) of white females, ages seven through 18, attending public schools in a defined area of Central Texas during October through December, 1984. Other correlates of blood pressure were also described for this sample.^ A survey was performed to obtain the data on height, weight, body mass, pulse rate, upper arm circumference and length, and blood pressure. Each subject self-assessed her secondary sex characteristics (breast and pubic hair) according to drawings of the Tanner stages of maturation. The subjects were interviewed to obtain data on personal health habits and menstrual status. Student age, ethnic group and place of residence were abstracted from school records. Parents or guardians of the subjects responded to a questionnaire pertaining to parental and subject health history and parents' occupation and educational attainment.^ In the simple linear regression analysis, sexual maturation and variables of body size were significantly (p < 0.001) and positively associated with systolic and fourth- and fifth-phase diastolic blood pressure. The demographic and socioeconomic variables were not sufficiently variant in this population to have differential effects on the relation between blood pressure and maturation. Stepwise multiple regression was used to assess the contribution of sexual maturation to the variance of blood pressure after accounting for the variables of body size. Sexual maturation (breast stage) along with weight, height and body mass remained in the multiple regression models for fourth- and fifth-phase diastolic blood pressure. Only height and body mass remained in the regression model for systolic blood pressure; sexual maturation did not contribute more to the explanation of the systolic blood pressure variance.^ The association of sexual maturation with blood pressure level was established in this sample of young white females. More research is needed first, to determine if this relationship prevails in other populations of young females, and second, to determine the relationship of sexual maturation sequence and change with the change of blood pressure during childhood and adolescence. ^

A STUDY OF ILLNESS AND RESERVOIRS ASSOCIATED WITH GIARDIA LAMBLIA IN RURAL EGYPT

A longitudinal investigation of the health effects and reservoirs of Giardia lamblia was undertaken in forty households located in a rural Nile Delta region of Egypt. Stool specimens obtained once weekly for six months from two to four year old children were cyst or trophozoite-positive in 42 percent of the 724 examined. The mean duration of excretion in all but one Giardia-negative child was seven and one-half weeks with a range of one to 17 weeks. Clinical symptoms of illness were frequently observed within a month before or after Giardia excretion in stool of children, but a statistical inference of association was not demonstrated.^ Seventeen percent of 697 specimens obtained from their mothers was Giardia-positive for a mean duration of four weeks and a range of one to 18 weeks. Mothers were observed to excrete Giardia in stool less frequently during pregnancy than during lactation.^ Nine hundred sixty-two specimens were collected from 13 species of household livestock. Giardia was detected in a total of 22 specimens from cows, goats, sheep and one duck. Giardia cysts were detected in three of 899 samples of household drinking water.^ An ELISA technique of Giardia detection in human and animal stool was field tested under variable environmental conditions. The overall sensitivity of the assay of human specimens was 74 percent and specificity was 97 percent. These values for assay of animal specimens were 82 percent and 98 percent, respectively.^ Surface antigen studies reported from the NIH Laboratory of Parasitic Diseases show that antigens of three Egyptian human isolates are different from each other and from most other isolates against which they were tested.^ The ubiquity of human and animal fecal contamination combined with estimates of ill days per child per year in this setting are substantial arguments for the introduction of a suggested mass parasite control program to intervene in the cyclical transmission of agents of enteric disease. ^