Hepatitis A incidence and hospital-based seroprevalence in Italy: a nation-wide study.
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 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 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.
Ansaldi
Filippo
F
Department of Health Sciences, University of Genoa, Via Pastore 1, Genoa, Italy. filippo.ansaldi@unige.it
Bruzzone
Bianca
B
Rota
Maria Cristina
MC
Bella
Antonino
A
Ciofi degli Atti
Marta
M
Durando
Paolo
P
Gasparini
Roberto
R
Icardi
Giancarlo
G
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D005843:Geography; D006506:Hepatitis A / Q000097:blood / Q000453:epidemiology*; D035922:Hepatitis A Antibodies / Q000097:blood*; D017957:Hepatitis A Virus, Human / Q000276:immunology*; D006761:Hospitals; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D012189:Retrospective Studies; D016036:Seroepidemiologic Studies; D017678:Sex Distribution
D035922:Hepatitis A Antibodies