Hepatitis A in workers exposed to sewage: a systematic review
- aUnit for Occupational and Environmental Health, Institute for Social and Preventive Medicine, University of Zurich, Sumatrastrasse 30, CH-8006 Zurich, Switzerland, bDivision of Epidemiology and Prevention of Communicable Diseases, Institute for Social and Preventive Medicine, University of Zurich, Switzerland, cSozialversicher- ungsanstalt des Kantons Zürich (SVA Zürich), Röngtenstrasse 17, Zürich, Switzerland
- Dr P Hotzphotz{at}ifspm.unizh.ch
- Accepted 4 July 2001
Abstract
OBJECTIVES To assess whether the scientific literature supports the hypothesis that workers exposed to sewage are at higher risk of hepatitis A (HA).
METHODS All original papers reporting epidemiological studies published in English, French, or German which reported on the risk of HA infection in workers exposed to sewage were eligible. They were identified by several methods and each original paper was assessed independently with a checklist by two people. Studies were classified according to the strength of their design. Non-eligible studies were also examined to assess the impact of publication bias. If the risk estimates diverged widely, causes for heterogeneity were assessed. A distinction was made between seroprevalence studies based on subclinical HA (defined only by the presence of anti-HA antibodies) and clinical HA.
RESULTS 17 eligible studies were identified. No indication of an increased risk of clinical HA could be found. For seroprevalence the studies with the strongest design suggested a slightly increased risk of subclinical HA with an odds ratio (OR) <2.5. Heterogeneity was considerable and precluded a meta-analysis. Considering non-eligible studies would still decrease the OR.
CONCLUSIONS The systematic review does not confirm an increased risk of clinical HA in workers exposed to sewage. An increased risk of subclinical HA cannot be excluded but the association between seropositivity and exposure to sewage was not strong and became still weaker if publication bias was taken into account.
