Wastewater workers and hepatitis A virus infection.

BACKGROUND The main occupational hazard of wastewater workers (WWs) is the direct exposure to the variety of infectious agents present in sewage material, with hepatitis A virus (HAV) being the most frequent one. Most epidemiological studies have shown a higher risk of hepatitis A among WWs, although some studies have produced conflicting evidence. AIMS To evaluate the hypothesis of increased risk of HAV infection in WWs. METHODS The prevalence of antibodies to HAV in 869 WWs was compared to 311 other subjects and analysed to detect the main potentially confounding variables. RESULTS Univariate analysis demonstrated that occupational exposure to sewage was not significantly associated with the prevalence of anti-HAV(+). The anti-HAV(+) prevalence was strongly associated with age and shellfish consumption (P < 0.05) when the subcategories of workers were examined separately (WWs and control group) and jointly. In the logistic regression model, a significant association between anti-HAV(+) prevalence and duration of employment (P < 0.05) was found. The interaction term (age x duration of employment) was significant (P < 0.001) when included in the logistic model. CONCLUSIONS This study shows that working in a wastewater treatment plant does not seem to be related to a greater prevalence of antibodies to hepatitis A. Moreover, the relative risk of HAV infection among WWs seems to be correlated with low anti-HAV(+) prevalence in the general population.