title: Hepatitis E, Helicobacter pylori and peptic ulcers in workers exposed to sewage: a prospective cohort study.
abstract: BACKGROUND
  Workers exposed to sewage may have an increased risk of infection by Helicobacter pylori and hepatitis E virus (HEV).
  
  
  OBJECTIVE
  To assess the incidence of clinical hepatitis E and peptic ulcers and the seroconversion rate of antibodies to H pylori and HEV in workers with and without sewage exposure.
  
  
  METHODS
  332 workers exposed to sewage and a control group of 446 municipal manual workers (61% participation rate) entered a prospective cohort study with clinical examination and determination of antibodies to H pylori and HEV (immunoglobulins G and A or G and M, respectively). Survival curves were examined with log rank tests and Cox regressions. Travelling to endemic areas, socioeconomic level, age, country of childhood, number of siblings, and personal protective equipment were considered as the main confounding factors.
  
  
  RESULTS
  Incidence of clinical hepatitis E was not increased in sewage workers. One peptic ulcer and three eradications were recorded in sewage workers compared with no peptic ulcers and 12 eradications in control workers. Incidence rates of approximately 0.01, 0.10, and 0.15 seroconversion/person-year for hepatitis E, H pylori IgG and H pylori IgA, respectively, were found in both exposed and non-exposed workers. Survival curves did not show an increased risk in sewage workers and no association with any exposure indicator was found. Sensitivity analyses did not alter these results.
  
  
  CONCLUSIONS
  Sewage does not appear to be a source of occupational infection by H pylori or HEV in trained sewage workers with personal protective equipment working in a region with good sanitation.
authors.affiliation: Division of Biostatistics, ISPM, University of Zurich, Zurich, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Tschopp
authors.forename: H
authors.initials: H
authors.lastname: Joller
authors.forename: S
authors.initials: S
authors.lastname: Jeggli
authors.forename: S
authors.initials: S
authors.lastname: Widmeier
authors.forename: R
authors.initials: R
authors.lastname: Steffen
authors.forename: S
authors.initials: S
authors.lastname: Hilfiker
authors.forename: P
authors.initials: P
authors.lastname: Hotz
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood; D004812:Epidemiologic Methods; D005260:Female; D016481:Helicobacter Infections / Q000453:epidemiology* / Q000209:etiology / Q000635:transmission; D016480:Helicobacter pylori / Q000276:immunology; D006508:Hepatitis Antibodies / Q000097:blood; D016751:Hepatitis E / Q000453:epidemiology* / Q000635:transmission; D016752:Hepatitis E virus / Q000276:immunology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000453:epidemiology*; D016273:Occupational Exposure / Q000032:analysis; D010437:Peptic Ulcer / Q000453:epidemiology*; D011482:Protective Devices / Q000706:statistics & numerical data; D012722:Sewage / Q000009:adverse effects*; D013557:Switzerland / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D006508:Hepatitis Antibodies; D012722:Sewage