Wastewater workers and hepatitis A virus infection
ABSTRACT 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.
To evaluate the hypothesis of increased risk of HAV infection in WWs.
The prevalence of antibodies to HAV in 869 WWs was compared to 311 other subjects and analysed to detect the main potentially confounding variables.
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.
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.
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ABSTRACT: To determine whether or not occupational exposure to sewage is associated with a higher seroprevalence of hepatitis A virus (HAV) infection, 600 sewage workers in Singapore were tested for total (IgG and IgM) antibody to HAV by enzyme immunoassay. Using logistic regression with stepwise procedure, the adjusted seroprevalence of sewage workers was 2.2 times higher than that of another non-occupationally exposed population group. Seroprevalence was significantly correlated with age and educational levels, the association being independent of the occupational association. The epidemiological data in the study show that sewage workers have an increased occupational risk of acquiring HAV infection and should be protected by active immunization.Epidemiology and Infection 09/1994; 113(1):121-8. DOI:10.1017/S0950268800051530 · 2.49 Impact Factor
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ABSTRACT: To evaluate the risk of hepatitis A virus (HAV) infection among sewage workers from occupational exposure to raw sewage. An analytical cross sectional study of 241 company employees with possible occupational exposure to sewage in a large water and sewerage company was carried out. Previous exposure to hepatitis A virus infection was assessed, as were its associations with possible risk factors. Frequent occupational exposure to raw sewage was a significant risk factor for HAV infection, independently of other known risk factors (odds ratio 3.73, 95% confidence interval 1.48 to 9.37). Of 50 employees who reported occupational exposure to raw sewage most of the time, 30 (60%) had had HAV infection. Employees who are likely to be at risk of frequent exposure should have their immunity ensured. The salivary assay for IgG anti-HAV used in the study was highly specific and would be suitable for prevaccination testing of older employees, who are more likely to be immune.Occupational and Environmental Medicine 09/1998; 55(8):567-9. DOI:10.1136/oem.55.8.567 · 3.23 Impact Factor
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ABSTRACT: To define the pattern of HAV infection in Italy and to study the differences among geographic areas (northern, central and southern Italy) and age-classes, we performed HAV antibody testing on sera collected in 1996–1997 from a large sample of the Italian population and compared the results with those of other seropreva-lence studies and with incidence data for the period 1985– 2005, calculated by a surveillance system specific for acute viral hepatitis based on symptomatic cases. A total of 3,561 sera, collected by hospital-based reference laboratories in 18 out of 20 Italian Regions, were tested; 1,138 (32%, 95% CI: 30.5–33.5) were positive. The age-adjusted prevalence was 60.1% and the age-specific rates were among the highest rates reported in Europe in the 1990s. The age-adjusted seroprevalence showed a significant north–south gradient, increasing from 55% in northern Italy to 68% in southern Italy. Age and area of residence were found to be strong predictors of previous HAV infection: the marked increase in prevalence with increasing age represents a strong cohort effect. In northern Italy, a marked increase with age was observed beginning with the 20-to 29-year age-class, whereas in southern Italy, such an increase was observed beginning with the 12-to 19-year age-class, indicating that northern Italy preceded southern Italy by 10–20 years in terms of improvements in hygiene and sanitation. The incidence of HAV infection shows an evi-dent peak in 1997, when an outbreak occurred in southern Italy, mainly affecting 15-to 24-year-old individuals. In the period from 1998 to 2005, the incidence drastically decreased (average of 3.2/100,000 inhabitants), reaching a minimum of 2/100,000 inhabitants in 2005.European Journal of Epidemiology 01/2008; 23:45-53. DOI:10.1007/s10654-007-9198-y · 5.15 Impact Factor