Hepatitis a Incidence and Hospital-Based Seroprevalence in Italy: A Nation-Wide Study

• Published in: European journal of epidemiology 2008-01, Vol.23 (1), p.45-53
• Main Authors: Ansaldi, Filippo, Bruzzone, Bianca, Rota, Maria Cristina, Bella, Antonino, degli Atti, Marta Ciofi, Durando, Paolo, Gasparini, Roberto, Icardi, Giancarlo
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Age differences; Age Distribution; Age groups; Age structure; Aged; Aged, 80 and over; Antibodies; Biological and medical sciences; Cardiology; Child; Child, Preschool; Children; Epidemiology; Female; General aspects; Geography; Hepatitis; Hepatitis A; Hepatitis A - blood; Hepatitis A - epidemiology; Hepatitis A Antibodies - blood; Hepatitis A virus; Hepatitis A Virus, Human - immunology; Hospitals; Human viral diseases; Humans; Incidence; Infant; Infant, Newborn; Infections; Infectious Diseases; Italy - epidemiology; Male; Medical sciences; Medicine; Medicine & Public Health; Middle Aged; Miscellaneous; Oncology; Population Surveillance; Public Health; Public health. Hygiene; Public health. Hygiene-occupational medicine; Retrospective Studies; Seroepidemiologic Studies; Sex Distribution; Vaccination; Viral diseases; Viral hepatitis
• ISSN: 0393-2990; 1573-7284
• DOI: 10.1007/s10654-007-9198-y

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 seroprevalence 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 ageadjusted seropre valence 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 evident 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.