PMID: 8822294

Issn Print: 0891-3668

Publication Date: 1996/02/01


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PREVALENCE OF HELICOBACTER PYLORI ANTIBODIES IN NORMAL CHILDREN

Felice Adler-Shohet; Pamela Palmer; George Reed; Kathryn Edwards

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Excerpt

Helicobacter pylori is a well-known cause of gastritis in children and adults1 and plays a major role in peptic ulcer disease.2 Recently H. pylori has been associated with an increased risk of gastric cancer.3, 4 Previous investigators have found an increasing prevalence of H. pylori infection with increasing age in asymptomatic people around the world.5, 6 Seroprevalence rates in the United States are consistently reported as approaching 60% in adults older than 60 years old.7 An earlier study on H. pylori in children between 3 and 20 years of age in the United States found an overall seroprevalence of 31%.8 This rate was higher than previously thought2 and rivaled seroprevalence rates of children in developing countries where prevalence approaches 70% by teenage years.9, 10 However, the children in that study8 were about to undergo surgical procedures for various medical complaints and may not be representative of normal healthy children. Also in that study sequential sera were not available to determine the actual time of seroconversion.
The current study looks at multiple yearly sera from healthy children followed in pediatric well child clinics. The purpose of this study was to assess the age at which asymptomatic children become seropositive for H. pylori and to determine whether seroconversion could be correlated with illness. In addition this study examines whether acquisition of infection occurs uniformly over time. Because hepatitis A is transmitted by the fecal-oral route, we hoped that by comparing seroprevalence rates for the two organisms we might support this mode of transmission for H. pylori.
Methods. Serum specimens were obtained from 200 children previously enrolled in one of a number of vaccine trials conducted at Vanderbilt University. Following protocols for other studies these children (between 2 and 11 years of age) had at least four consecutive yearly serum samples between 1980 and 1994. Apart from routine sampling 100 of the children participating in these studies were told to come to our institution for an evaluation and an additional blood drawing if they became ill at any time during the study period. Additionally information about parental education level, number of rooms in the house and family size was obtained for these enrollees. For all enrollees parents completed demographic information from the time of their enrollment in the initial vaccine trials. Information obtained included age, race and gender for all children enrolled. Children with any chronic medical complaints were excluded from the study. These yearly sera from healthy, asymptomatic children were tested for the presence of IgG against H. pylori with an enzyme-linked immunosorbent assay from a commercial kit (Pyloristat®; Biowhittaker, Inc.). This kit has previously been proved in children to be sensitive and specific for the detection of IgG against H. pylori.11 The most recent serum from each child was evaluated and if proved to contain anti-H. pylori IgG, consecutive yearly sera from that child were evaluated until the first IgG-negative serum was found. This was done to determine the age at which the seropositive children were initially infected.
Sera from all 200 children were also tested for the presence of IgG antibody against hepatitis A antigen using enzyme-linked immunosorbent assays from a commercial kit (HAVAB EIA®; Abbott Laboratories). This test was performed on the same serum samples described above, and the results of the hepatitis A enzyme-linked immunosorbent assay were compared with the H. pylori results.
The study was approved by the Institutional Review Board of Vanderbilt University Medical Center.
Kaplan-Meier type survival curves were used to estimate probability of no seroconversion. One minus these estimated values was plotted to illustrate seroconversion rates by age.
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