Helicobacter pylori Prevalences and Risk Factors among School Beginners in a German Urban Center and Its Rural County

Environmental Health Perspectives, June, 2001 by Olf Herbarth, Peter Krumbiegel, Gisela J. Fritz, Matthias Richter, Uwe Schlink, Detlef M. Muller, Thomas Richter

In 1998, the Helicobacter pylori [[sup.13]C]urea breath test was offered to all school beginners (birth cohort 1991/1992) in the city of Leipzig and in Leipzig County, Germany, to determine the colonization prevalence and potential transmission pathways of the bacterium. A total of 3,347 school beginners participated in the test, and 2,888 parents completed the detailed, self-administered questionnaire. The H. pylori prevalence was 6.5% [95% confidence interval (CI), 5.3-7.6] in the city and 5.7% (CI, 4.2-7.0) in the county. Using cluster analysis (WARD's method, Euclidean distances), we identified different sets of variables (confirmed by multivariate logistic regression analyses [odds ratios (ORs)] that are significantly associated with H. pylori positivity. Among city children, the risk is significantly increased with contact to a pet hamster (OR = 2.4; 95% CI, 1.2-4.7; p [is less than] 0.015) and travels to Asian countries (OR = 3.7; 95% CI, 1.6-8.7; p [is less than] 0.002). Among county children, H. pylori positivity increased significantly with drinking of water from nonmunicipal sources (OR = 16.4; 95% CI, 3.1-88.5; p [is less than] 0.001), more than 3 children living in a household (OR = 4.2; 95% CI, 1.2-14.6; p [is less than] 0.02), and contact with pet hamsters (OR = 2.4; 95% CI, 1.0-5.7; p [is less than] 0.04). These data suggest that, in a general population sample, indirect fecal-oral transmission and living conditions are important risk factors in the spread of H. pylori infection. However, clinical symptoms do not necessarily indicate H. pylori positivity. Key words: [sup.13]C breath test, Germany, Helicobacter pylori, prevalences, risk factors, rural county, school beginners, urban center. Environ Health Perspect 109:573-577 (2001). [Online 21 May 2001]

http://ehpnet1.niehs.nih.gov/docs/2001/ 109p573-577herbarth/abstract.html

Helicobacter pylori is one of the most common pathogens. Since the observations of Warren and Marshall in 1983/1984 (1), its significance as a causal agent for peptic ulcers and public health problems is evident. Numerous papers have been published discussing potential risk factors of transmission and infection.

In a recent review of H. pylori epidemiologic studies, the European Helicobacter pylori Study Group (2) concluded that "The route of transmission still remains unclear." The authors observed problems in the interpretation of some past studies in relation to study design, selection and size of the study population, and the statistical methods applied. The recommendation was that future epidemiologic studies take these aspects into consideration.

The large number of cases and the high cost of medical treatment have now turned the focus of epidemiologic research toward certain risk populations. Preschool children are thought to be the main risk population (3). Generally accepted risk factors for the aquisition of H. priori infection are socioeconomic status, childhood living conditions (4), and large family size (5). In a recent German study, family history of gastric disease correlated with aquisition of the bacterium (6), whereas pets have not been considered a risk factor (7). As far as the routes of transmission are concerned, the results have been contradictory (2). There is no doubt that the bacterium gains entry to the stomach via the mouth. Oral-oral, fecal-oral, and iatrogenic spread, as well as several vectors such as domestic cats, nonhuman primates, and the domestic housefly, have all been discussed as possible routes of transmission; however, a major route has not been identified (8).

Because this organism appears to be ubiquitous and may be picked up anywhere, we hypothesized that indirect fecal-oral transmission could possibly be a dominant pathway in its acquisition. Thus, we conducted this study to determine potential sources of H. pylori in the environment of young children. The data are based on a detailed parent-completed questionnaire designed to explore a wide range of possible risk factors and an H. pylori colonization screening test administered to the entire 1998 school entry population in Leipzig, Germany, as well as its rural region, the County of Leipzig.

Materials and Methods

The Leipzig Helicobacter pylori study was a joint project of the UFZ (Centre for Environmental Research Leipzig-Halle, GmbH), the University Children's Hospital Leipzig, and the Departments of Public Health, City and County of Leipzig, conducted in the fall and winter of 1997/1998. The investigation included all children eligible to enter grade one in the fall of 1998. Participation was voluntary, and the test was scheduled to be administered during the mandatory medical examinations carried out by the Departments of Public Health. The study involved the administration of the gastric H. pylori colonization test using the stable-isotope-aided in vivo [[sup.13]C]urea breath test and a detailed, parent-completed questionnaire. The [[sup.13]C]urea breath test involved two breath samples, one taken before and another 30 min after drinking 75 mL orange juice with 75 mg [[sup.13]C]urea (99.3 atom% [sup.13]C; chemical purity according to U.S. Pharmacopeia assay: 99.8%; Chemotrade Leipzig, portioned out by the Children's Hospital pharmacy). A child was considered infected with H. pylori (positive) when the [sup.13]C values of the two exhaled carbon dioxide test samples (measured by a [sup.13]C isotope analyzer, FANci; Dr. Fischer Analysen, Leipzig, Germany) differed significantly. The underlying biochemical principle is that [[sup.13]C]urea is split in the stomach only in the presence of H. priori.