Victor M. Cardenas

Greater Than 95% Success with 14-day Bismuth Quadruple Anti- Helicobacter pylori Therapy: A Pilot Study in US Hispanics

A combination capsule of bismuth, metronidazole, and tetracycline plus omeprazole given as 10‐day therapy has an overall effectiveness of 92–93% in per‐protocol analysis (Grade B) with eradication of 86–91% of metronidazole‐resistant Helicobacter pylori. This study aimed to explore whether extending the duration to 14 days would improve overall effectiveness per protocol to ≥95% (Grade A) in a population in which metronidazole resistance was anticipated to exist.

Smoking and Helicobacter pylori infection in a sample of U.S. adults.

Background: Although the prevalence of Helicobacter pylori infection has been assessed in the National Health and Nutritional Examination Survey (NHANES), its possible relation with smoking has not been fully explored. Methods: We used the 1999–2000 NHANES data to examine whether smoking affects the prevalence of H. pylori infection in adults (n = 3689). The prevalence of H. pylori infection, as assessed by anti-H. pylori IgG enzyme-linked immunoassay, was computed according to smoking history and levels of serum cotinine. Results: Current smoking was associated with an increased prevalence of H. pylori infection (prevalence odds ratio =1.9; 95% confidence interval = 1.4–2.5) after controlling for possible confounders. Current smoking, as measured by increased serum cotinine, was also associated with an increased prevalence of H. pylori infection (1.6; 1.3–2.0). There was no evidence of a dose–response relation. Conclusions: Smoking may contribute to the persistence of H. pylori infection.

Cross-Border Purchase of Medications and Health Care in a Sample of Residents of El Paso, Texas, and Ciudad Juarez, Mexico

BACKGROUND We examined data from a US-Mexico bi-national survey conducted among adult residents of El Paso, Texas, and Ciudad Juarez, Mexico, to assess frequency of purchase of medications and use of health care services across the border. METHODS We analyzed questionnaire data from face-to-face interviews of 1000 randomly selected adults on both sides of the border to assess prevalence and prevalence ratios using log binomial logistic regression analysis. RESULTS One-third of adult residents of El Paso and 5% of those in Ciudad Juarez reported crossing the border to purchase medications (P < .001). Lack of health insurance in the United States was associated with crossing the border to purchase medications. Nine percent and 7% of US residents traveled to Mexico seeking dental and medical care, respectively. Mexican nationals traveling to the United States to purchase medications or health care services were more likely to be uninsured and more-educated men. CONCLUSION US residents of areas along the border in close proximity to Mexico often travel south to purchase medications. Other health care services are also utilized, although at lower rates. These patterns may be attributed to a number of barriers to health care in the United States.

Evaluation of a novel stool native catalase antigen test for Helicobacter pylori infection in asymptomatic North American children.

Rapid immunochromatographic tests for Helicobacter pylori infection have been developed to allow “near-patient” testing. We therefore performed a pilot study to test a rapid immunochromatographic stool antigen test for the diagnosis of H pylori infection in asymptomatic children. We tested stool specimens collected from children participating in a cohort study in the United States and Mexico. H pylori–positive status was defined by positivity on at least 2 tests: a commercial H pylori stool antigen enzyme immunoassay, an immunoglobulin G antibody enzyme immunoassay, and the 13C-urea breath test. Negative H pylori status was defined by negative findings of all of these tests. Of 52 children (22 girls, 30 boys) 25 were H pylori–positive, 19 H pylori–negative, and 8 uncertain (eg, presumably negative; positive findings on 1 of the 3 noninvasive tests). The sensitivity and specificity of the new stool antigen test for those with definite H pylori status were 100% (exact 95% CI 86.3%–100% and 82.4%–100%, respectively). This rapid stool antigen test may prove useful for point-of-care testing and epidemiological field studies. Larger prospective studies are needed in symptomatic and asymptomatic children for more precise estimates.

Population-based survey of taeniasis along the United States–Mexico border

Abstract Taenia solium and T. saginata are zoonotic tapeworms of substantial medical and economic importance. Although human taeniasis is widely recognised as an endemic problem in Mexico, its presence in the United States is poorly understood. The first population-based study to estimate the prevalence of human infection with Taenia tapeworms along the Texas–Mexico border has recently been conducted. Households were interviewed in the Texan city of El Paso and in the neighbouring Ciudad Juárez, in Mexico. Faecal samples from household members were then checked for Taenia eggs by flotation and/or for Taenia copro-antigens in an ELISA. The overall prevalence of taeniasis in this border region was found to be 3% but, compared with the residents of Juárez, El Paso residents were 8.6-fold more likely to be tapeworm carriers. The interviews revealed some important differences between the two study sites, particularly the more frequent use of anthelminthic drugs on the Mexican side of the border. These findings have implications in terms of the planning of effective health-education campaigns to decrease the prevalence of taeniasis in the human populations along the Texas–Mexico border.

Utilization and purchase of medical care services in Mexico by residents in the United States of America, 1998-1999

OBJECTIVES We assessed self-reported frequency of purchase of medications and medical care services in Mexico by southern New Mexico (United States, [U.S.]) residents in relation to their medical insurance coverage. METHODS We analyzed data obtained in 1998 and 1999 from a health interview survey of residents in a six-county region of southern New Mexico, using prevalence and logistic regression methods for complex survey data. RESULTS About 22% of southern New Mexico residents had purchased medications and 11% had sought medical care in Mexico at least once during the year preceding the survey. When we adjusted for the effects of other variables, persons able to pay for services out of pocket and those who were uninsured were more likely than persons who were fully covered to purchase medications or medical care in Mexico. CONCLUSIONS Large numbers of people residing near the border in New Mexico traveled south to Mexico to purchase medications and medical care. Lack of medical insurance was associated with higher frequencies of these purchases. There seems to be a need to establish relationships between U.S. private and public care plans and Mexican medical care providers to identify appropriate mechanisms for U.S. residents to purchase medical care in Mexico.

Helicobacter pylori Eradication and Change in Markers of Iron Stores Among Non―iron-deficient Children in El Paso, Texas: An Etiologic Intervention Study

Objectives: We assessed whether Helicobacter pylori eradication was followed by changes in iron stores among non–iron-deficient children. Materials and Methods: Double-blind randomized intervention trial on 110 asymptomatic 3- to 10-year-olds with H pylori infection assigned to any of the following 4 arms: both quadruple eradication and iron supplementation, either quadruple sequential eradication or iron supplementation, or placebo only. Hemoglobin, transferrin saturation, and serum ferritin were measured at baseline and 8 months later to assess changes according to study arm, H pylori infection status at ≥45 days, and cytotoxin-associated gene product A status. Results: Intent-to-treat (n = 110) and per-protocol (n = 90) analyses revealed no differences across study arms in changes of iron stores. However, we found that those who had their infection eradicated had a 3-fold increased average change from baseline serum ferritin compared with that of children who remained infected (P < 0.05). Eradication of infection by cytotoxin-associated gene product A negative strains was associated with a larger ferritin increase. Conclusions: In this double-blind randomized trial, the first among non–iron-deficient, asymptomatic H pylori–infected children living in the contiguous United States, we found no effect of H pylori eradication regarding changes in iron stores. However, those who had their infection eradicated at follow-up had a significantly larger increase in serum ferritin from baseline.

Confounding by time since hire in internal comparisons of cumulative exposure in occupational cohort studies.

We use a simple, empirical model to describe the healthy worker effect mortality pattern. Under this simple model, internal comparisons of risk with increasing cumulative exposure will tend to be biased away from the null because of the healthy worker effect. We illustrate the potential magnitude of the bias in a simple situation and show that controlling for time since hire, by means of standard epidemiologic methods, eliminates the bias. Time since hire also is a concern of occupational epidemiologists because of the issue of induction time; sufficient time may not have elapsed among recently hired workers for an exposure to manifest its effect on disease occurrence. Provision for an adequate induction period can be addressed, like the concern raised in this paper, by restricting the analysis to workers first employed many years before the start of the follow-up period. (Epidemiology 1993;4:336–341)

Double-blind randomized trial of quadruple sequential Helicobacter pylori eradication therapy in asymptomatic infected children in El Paso, Texas.

Objectives: We assessed the efficacy of a novel quadruple sequential 10-day eradication therapy, its compliance, and reported adverse events in a sample of asymptomatically Helicobacter pylori–infected children in El Paso, Texas, as part of a study aiming to assess the influence of this infection on the levels of markers of iron stores. Patients and Methods: Using a double-blind randomized trial design, 110 asymptomatic children ages 3 to 11 with H pylori infection were randomly assigned to receive either a 10-day course of sequential eradication therapy plus 6 weeks of iron supplementation, eradication therapy plus placebo, iron supplementation plus placebo, or placebo only. H pylori infection status was assessed ≥45 days after treatment using the urea breath test. Analyses compared the proportion of subjects cured according to assignment to and completion of the sequential eradication therapy. Results: Intent-to-treat and per-protocol analyses indicated that 44.3% and 52.9%, respectively, of the children receiving the novel quadruple sequential therapy had their infection eradicated compared with 12.2% and 15.4% in the arms receiving iron or placebo only, respectively (P < 0.001 in both analyses). Study medications were taken with no or only mild adverse events in most children. Conclusions: A quadruple sequential regimen eradicated H pylori in only half the asymptomatic children receiving this treatment. There was no difference in the cure rates of those receiving iron supplementation and those receiving placebo.

Hyperendemic H. pylori and tapeworm infections in a U.S.-Mexico border population

Objective. A higher incidence of infectious disease has been documented in U.S. regions bordering Mexico compared with non-border areas. We assessed the prevalence of important gastrointestinal infections in Ciudad Juarez, Mexico, and El Paso, Texas, the largest binational community along the U.S.-Mexico border. Methods. Fecal specimens from a sample of the asymptomatic population representing all ages were tested for Helicobacter pylori (H. pylori), Cryptosporidium spp., Giardia spp., and other intestinal parasitic pathogens using flotation, immunoassays, and/or polymerase chain reaction. We also measured indicators of microbiological contamination of drinking water, hands of food preparers, and kitchen surfaces. Results. Overall, of the 386 participants, H. pylori was present in 38.2%, Taenia spp. in 3.3%, Giardia spp. in 2.7%, Cryptosporidium spp. in 1.9%, Entamoeba dispar in 1.3%, and Ascaris lumbricoides and Necator americanus in 0.3% of the study subjects; Cyclospora spp. and Entamoeba histolytica were not found. H. pylori infection was associated with handwashing (prevalence ratio [PR] = 1.3, 95% confidence interval [CI] 1.0, 1.8). Taenia spp. was found more often on the U.S. side (PR=8.6, 95% CI 2.3, 30.8). We did not find an association between these infections and the occurrence of total coliforms or fecal coliforms on kitchen surfaces. In addition, Escherichia coli was not found in any drinking water sample. Conclusion. The study results indicated that H. pylori and Taenia spp. infections may be highly prevalent along the U.S.-Mexico border. Additional research is necessary to adequately characterize the prevalence, as well as determine whether interventions that reduce these infections are warranted.