Karen J. Goodman

A Comprehensive Review of the Natural History of Helicobacter pylori Infection in Children

Across populations of children, Helicobacter pylori prevalence ranges from under 10% to over 80%. Low prevalence occurs in the U.S., Canada, and northern and western Europe; high prevalence occurs in India, Africa, Latin America, and eastern Europe. Risk factors include socioeconomic status, household crowding, ethnicity, migration from high prevalence regions, and infection status of family members. H. pylori infection is not associated with specific symptoms in children; however, it is consistently associated with antral gastritis, although its clinical significance is unclear. Duodenal ulcers associated with H. pylori are seldom seen in children under 10 years of age. H. pylori-infected children demonstrate a chronic, macrophagic, and monocytic inflammatory cell infiltrate and a lack of neutrophils, as compared with the response observed in adults. The effect of H. pylori infection on acid secretion in children remains poorly defined. The events that occur during H. pylori colonization in children should be studied more thoroughly and should include urease activity, motility, chemotaxis, adherence, and downregulation of the host response. The importance of virulence determinants described as relevant for disease during H. pylori infection has not been extensively studied in children. Highly sensitive and specific methods for the detection of H. pylori in children are needed, especially in younger pediatric populations in which colonization is in its early phases. Criteria for the use of eradication treatment in H. pylori-infected children need to be established. Multicenter pediatric studies should focus on the identification of risk factors, which can be used as prognostic indicators for the development of gastroduodenal disease later in life.

Isolation and Genotyping of Helicobacter pylori from Untreated Municipal Wastewater

ABSTRACT For this study, we isolated Helicobacter pylori from wastewater by a series of steps beginning with immunomagnetic separation and cell culture. After Gram staining and three standard microbial tests, the 16S rRNA sequences of a total of 23 out of 37 putative H. pylori isolates were verified by PCR. Eleven H. pylori isolates were genotyped and fell into four vacA classes: those with the vacA allelic variants s1a and m1, s1b and m1, s2 and m2, or s2 and m1. Most H. pylori isolates were of the vacA s1a/m1 type, which has been shown to be associated with advanced diseases based on genotyping of H. pylori from gastric cancer patients. These results demonstrated that H. pylori survives in water and may be a potential source of H. pylori transmission, especially where water is not adequately treated.

Hepatitis B Vaccination in High-Risk Infants: 10-Year Follow-Up

The long-term efficacy of hepatitis B vaccination among high-risk infants was determined in 805 vaccine responders, immunized at birth in Taiwan during 1981-1984 and followed to age 10 years, via life table survival and Cox multivariate analyses. At 10 years, cumulative persistence of antibody to hepatitis B surface antigen (anti-HBs) was 85%, and cumulative incidence of hepatitis B virus (HBV) infection was 15%. Three children became carriers. Twelve-month anti-HBs titer was the strongest predictor of efficacy. The higher the initial titer, the lower the risk of anti-HBs loss (relative risk [RR], 0.26 for titer of 100-999 mIU/mL; RR, 0.08 for titer >1000 mIU/mL; P<.001) and HBV infection (RR, 0.55 and 0.27; P<.05). Maternal hepatitis B e antigen positivity but not hepatitis B immunoglobulin dose or gender predicted greater antibody persistence to age 10 years. Because the level of antibody persistence remained high and few became carriers, booster revaccination within 10 years seems unnecessary.

Lead editorial: The need for greater perspective and innovation in epidemiology

This editorial introduces the new online, open-access, peer-reviewed journal, Epidemiologic Perspectives & Innovations. Epidemiology (which we define broadly, to include clinical research and various approaches to studying the health of populations) is a critically important field in informing decisions about the health of individuals and populations. But the desire for new information means that the health science literature is overwhelmingly devoted to reporting new findings, leaving little opportunity to improve the quality of the science. By creating a journal dedicated to all topics of and about epidemiology, except standard research reports, we hope to encourage authors to write more on the neglected aspects of the field. The journal will publish articles that analyze policy implications of health research, present new research methods and better communicate existing methods, reassess previous results and dogma, and provide other innovations in and perspectives on the field. Online publishing will permit articles of whatever length is required for the work, speed the time to publication and allow free access to the full content.

Helicobacter pylori Infection in Pregnant Women from a U.S.–Mexico Border Population

Helicobacter pylori infection causes chronic digestive diseases that disproportionately affect Hispanics and other immigrant groups in the United States. Information on the epidemiology of H. pylori infection in pregnant women who reside along the U.S.-Mexico border is critical to understanding the dynamics of current H. pylori transmission patterns within families along the border. We describe the epidemiology of H. pylori infection in pregnant women recruited from Women, Infants, and Children (WIC) clinics in El Paso, Texas, and Mexican Social Security Institute maternal-child clinics in Ciudad Juarez, Mexico, from April 1998 to October 2000. We interviewed participants regarding environmental factors and tested their serum for IgG antibodies. We used logistic regression to estimate associations between environmental exposures and the odds of H. pylori prevalence. Definitive serological tests were available from 751 women. Seroprevalence was 74% in Juarez women and 56% in El Paso women. Prevalence increased with age, crowding, poor sanitation, and residence in Mexico, decreased with education, and was not associated with the womans number of living children. In the U.S.-Mexico border region, women of reproductive age have a high prevalence of H. pylori infection, apparently related to poor socioeconomic conditions.

How Do Practicing Clinicians Manage Helicobacter pylori-Related Gastrointestinal Diseases in Germany? A Survey of Gastroenterologists and Family Practitioners

Since the bacterium H. pylori was identified in 1982, overwhelming evidence has implicated it as the causal factor in the occurrence and relapse of peptic ulcer disease. The major objective of this study was to examine the extent to which physicians recognize H. pylori as a causal agent in peptic ulcer disease or as potential cofactor in other gastrointestinal diseases, and the extent to which this knowledge has influenced diagnostic and therapeutic practices.

Hill's Criteria of Causation

The term criteria of causation (or causal criteria) is often applied to Sir Austin Bradford Hills (8) list of factors to consider before inferring causation from an observed association. This list is widely taught and cited, despite widespread cautions about the limitations of the list, by Hill and others, and despite lack of evidence that invoking such criteria is useful. This entry describes Hills views on assessing causation and what others have since said on the subject of causal criteria. Keywords: causal inference; causation; causality; criteria of causation epidemilology

Implications of Helicobacter pylori infection for stomach cancer prevention

Accumulating evidence has implicated Helicobacter pylori, an established cause of chronic gastritis and peptic ulcer, in the etiology of gastric cancer. Control of this infection would reduce the occurrence of chronic gastritis and peptic ulcer and might substantially lower the risk of stomach cancer as well. The public health impact of this infectious agent warrants efforts to identify preventive measures. This paper reviews the evidence linking H. pylori infection to gastric cancer and evaluates the potential for control in high-risk populations. Current obstacles to H. pylori control are discussed, including the link to poor socioeconomic conditions, difficulty in identifying incident cases, lack of natural immunity to reinfection, limited effectiveness of antibiotic therapy in high-prevalence populations, and incomplete knowledge regarding the reservoir of infection, mode of transmission, host susceptibility factors, and the potential for developing an effective vaccine. Worthwhile avenues of research include studies designed to identify modifiable risk factors for acquisition of the infection, modifiable host factors that may increase resistance to chronic infection, more effective antibiotic therapies, and effective vaccines.