title: Estimated incidence of hepatitis A virus infection in Catalonia.
abstract: OBJECTIVE
  Hepatitis A normally is underreported by statutory disease reporting systems. The objective of this study is to estimate the incidence of hepatitis A virus (HAV) infection from prevalence surveys of infection carried out in representative samples of the population in 1989, 1996, and 2002 and the reported disease incidence during 1991 to 2003 in Catalonia.
  
  
  METHODS
  The real incidence of the infection was estimated from the reported incidence adjusted by the prevalence of susceptible individuals and the probability of presenting clinical manifestations. The bootstrap resampling technique was used to calculate 95% confidence intervals (CIs) of reported, clinical, and all infection cases.
  
  
  RESULTS
  The infection rate estimated by the bootstrap method was 31.1/100,000 person-years (bootstrap studentized 95% CI, 19.4-56.0), and the rate of clinical hepatitis was 20.0/100,000 person-years (95% CI, 11.8-39.9), rates that were 6.3 and 4.1 times greater than the reported rate during the same period, respectively.
  
  
  CONCLUSIONS
  In children younger than 5 years, the estimated infection rate was 13.8 times greater than the reported rate. Combined use of reported cases and results of seroprevalence surveys suggest that underreporting of HAV infection is substantial in Catalonia, especially in children younger than 5 years.
authors.affiliation: Epidemiological Surveillance Unit, Generalitat of Catalonia, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Oviedo
authors.forename: M Pilar
authors.initials: MP
authors.lastname: Muñoz
authors.forename: Angela
authors.initials: A
authors.lastname: Domínguez
authors.forename: Gloria
authors.initials: G
authors.lastname: Carmona
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001699:Biometry; D002648:Child; D002675:Child, Preschool; D018563:Disease Notification / Q000706:statistics & numerical data*; D006506:Hepatitis A / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D007223:Infant; D008875:Middle Aged; D013030:Spain / Q000453:epidemiology