a SLACK Incorporated newspaper
April 1999
HOUSTON, Texas - While the prevalence of Helicobacter pylori infection is inversely related to socioeconomic status in childhood, different races and ethnic groups have different risks of acquiring the infection, according to a study of children in a biracial community with a homogeneous lower middle socioeconomic class.
Although socioeconomic class is a factor in the acquisition of H. pylori variables such as social behavior, customs and dietary habits that differ among ethnic groups complicate an interrelationship between socioeconomic status and the infection, according to Hoda M. Malaty, MD, PhD, associate professor of medicine at Baylor College of Medicine in Houston, and the study's lead author.
For physicians, this means that the identification and assessment of H. pylori should consider the patient's ethnic group and symptoms, as well as socioeconomic status, as variables, Malaty said.
The study assessed the pattern of acquisition and loss of H. pylori infection among 212 children who were monitored within the framework of the Bogalusa Heart Study in Louisiana. This biracial community has a fairly stable population of 35% black and 65% white.
The children were followed from childhood at ages 7, 8 and 9 in 1973-1974 over a 12-year period to young adulthood at ages 19, 20 and 21 in 1985-1986. The study also included cross-sectional surveys conducted three to five years apart and followed a selected cohort of children annually. The presence of serum IgG antibodies to H. pylori was used as a measurement of infection of the gastric mucosa.
When initially tested at ages 7 through 9, 19% of the total children tested had H. pylori infection in a group that included 40% of the black subjects and 11% of the white subjects. At the 12-year follow-up, 33% of the total group was seropositive, with a consistently higher prevalence among blacks.
During the observation period, black children were more likely to remain infected or become reinfected and less likely to lose the infection. Of the 171 children who were seronegative at age 7, 8 or 9, 22% became infected by young adulthood, with a seroconversion rate to H. pylori four times higher among blacks than among whites. At the follow-up, 50% of the white children who tested seropositive at the initial observation had cleared the infection compared with 4% of the blacks. The relative risk of children ages 7 through 9 years with H. pylori infection remaining infected at ages 19 through 22 was 78%, ranging from 50% among whites to 96% among blacks.
One reason for the discrepancy in infection rates may be the differences in access to health care among the races, Malaty said. Since treatment for H. pylorihad not yet been discovered at the time of the study, no direct therapy for the infection was used. However, the high rate of loss of H.pyloriin the white children may have been related to their access to and use of antimicrobials for the treatment of other common infections during the study period.
The study's authors also considered that infection discrepancies may have been attributable to more intense exposure of the black children to H. pylori because of a higher rate of infection in family members in blacks vs. whites. While there is no definite consensus as to the method of H. pylori transmission, a study of preschool children and their parents in Ulm, Germany, suggested that infected parents, especially infected mothers, may play a key role in the transmission of H. pylori within families.
The Ulm study included 1,221 preschool-age children who were screened between January and July 1997 at mandatory medical examinations administered prior to school attendance. The subjects' infection status was determined by C-urea breath test, which was indicative of current infection with H. pylori Breath samples were collected from the child and only his or her accompanying parent at the examination. Mothers accompanied 86% of the children; fathers accompanied 11%.
In the group of 329 children whose mothers were currently infected with H. pylori 24.6% tested positively. Of the 618 children whose mothers were not currently infected with H. pylori only 1.9% were infected. The prevalence of infection was 33.9% among the 62 children whose fathers were currently infected, compared with 6.2% of the 65 children whose fathers were not currently infected.
Based on these statistics, with adjustments for covariants for nationality, age, sex, place of birth, education of father and mother, history of breastfeeding, history of antibiotic use and housing density, the adjusted odds ratios, with a 95% confidence interval, were: 7.9 for children whose mothers were infected and 3.8 for children whose fathers were infected.
To further support the observation that H. pylori infection is transmitted mainly from parent to child, and not vice versa, the authors, headed by Dietrich Rothenbacherat the University of Ulm, Germany, noted "... if one considers the fact that there is a low risk of reinfection after successful eradication in adults and in children older than 5 years, in contrast to children younger than 5 years, everything points to childhood as the critical period of H. pyloriinfection ... the peak time of infection seems to be between the first and fifth years of life, and in this period the mother is usually the family member with the closest contact with the child."
A previous study by the same group in Germany found a strong association between a maternal history of peptic ulcer, which is strongly related to H. pylori infection status, and the H. pylori infection status of children, but no association with a paternal history of peptic ulcer. While this information may support the theory of mother-to-child transmission of the infection, it also emphasizes its long-term consequences.
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Because of the known association of H. pylori with the development of chronic gastritis and peptic ulcer disease, as well as gastric adenocarcinoma and primary gastric B-cell lymphoma, the importance of obtaining an accurate family history concerning the prevalence of this infection, as well as regarding these related diseases, should not be overlooked, Malaty said.
"If someone has H. pylori in the family, the physician also has to question if they have a family history of peptic ulcer disease or stomach cancer. He should be aware of it because, if there are the right genes for ulcers, the child might grow up and his chances of having ulcer disease is higher than someone who doesn't have H. pylori" Malaty said.
For more information:
- Malaty H, Graham D, Wattingney W, et. al. Natural history of Helicobacter pylori infection in childhood: 12-year follow-up cohort study in a biracial community. Clin Infect Dis 1999;28:279-82.
- Rothenbacher D, Bode G, Berg G, et. al. Helicobacter pylori among preschool children and their parents: evidence of parent-child transmission. J Infect Dis.1999;179:398-402.
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