Estimated Incidence of Hepatitis A Virus Infection in Catalonia
Introduction
Hepatitis A is an infection produced by the hepatitis A virus (HAV), a Hepatovirus belonging to the Picornaviridae family (1). HAV infection may be asymptomatic or lead to acute hepatitis, which generally is self-limiting, but the duration and severity increase with age 2, 3. Although most cases are benign, complications include fulminant hepatitis and death. Deaths from HAV infection are very infrequent in people younger than 40 years, but case-fatality rates are 2% in the 50- to 59-year age group and 13% in people older than 70 years (4).
Because of its epidemic potential 5, 6, the potential severity of the disease in adults (7), and the existence of an effective vaccine since the middle of the 1990s 8, 9, there is agreement that surveillance of hepatitis A is necessary 4, 10, 11.
One of the main difficulties in hepatitis A surveillance is determining the real incidence (12). Although physicians are obliged to report the disease to the health services in many countries, underreporting is common 13, 14 because the disease evolves and anicteric forms, with nonspecific clinical manifestations, are very frequent (6).
Seroprevalence studies of nonvaccinated subjects 15, 16 allow the proportion of infected people in different age groups to be estimated 17, 18, 19, 20, 21, but do not allow estimation of the frequency of new infections.
Integration of data collected from surveys of reported cases was suggested as an alternative to estimate the real incidence of an infectious disease 22, 23, 24.
The objective of this study is to estimate the incidence of HAV infection from available prevalence surveys and data on the reported incidence of clinical cases of hepatitis A in Catalonia.
Section snippets
Data Sources
Reporting of hepatitis A disease has been obligatory in Catalonia since 1990. All cases of hepatitis A reported to the Department of Health of the Generalitat of Catalonia between 1991 and 2003 were included, aggregating this information annually.
Prevalence data for HAV infection were obtained from seroprevalence studies carried out in Catalonia in 1989, 1996, and 2002 25, 26. Data from the 1989 study were used to estimate the incidence in 1991 to 1993; those from 1996, the incidence in 1994 to
Results
Figure 1 shows prevalence curves of HAV antibodies according to age groups for the 1989, 1996, and 2002 surveys. The prevalence in people 40 years or older was always more than 90%. In subjects younger than 40 years, a decrease in age-related prevalence was observed over time.
As listed in Table 1, the reported incidence rate for the study period was 4.9/100,000 person-years. The estimated rate of total infections was 31.1/100,000 person-years, and that of clinical infections, 20/100,000
Discussion
To decide which HAV vaccination strategy should be adopted, the intensity of both new infections and clinical cases of the disease must be determined.
In this study, the estimated incidence of clinical cases of hepatitis A was 20.0/100,000 person-years, and the rate of HAV infection was 31.1/100,000 person-years, values 4.1 and 6.3 times greater than the reported rate of 4.9/100,000 person-years, respectively.
Armstrong and Bell (28) found that the rate of the disease was 4.3 times the reported
References (52)
- et al.
Epidemiology and risk group in the USA
Vaccine
(1992) - et al.
Effectiveness of a mass hepatitis A vaccination programme in preadolescents
Vaccine
(2003) - et al.
Quantifying the impact of hepatitis A immunization in the United States, 1995-2001
Vaccine
(2004) - et al.
Hepatitis A virus
- et al.
Hepatitis viruses
- et al.
Viral hepatitis A with prolonged course in adults
Gastroenterol Clin Biol
(1996) - et al.
Guidelines for the control of hepatitis A virus infection
Commun Dis Public Health
(2001) - et al.
Imported rocket salad partly responsible for increased incidence of hepatitis A cases in Sweden, 2000-2001
Eurosurveillance
(2001) - et al.
Sources of infection among persons with acute hepatitis A and no identified risk factors during a sustained community-wide outbreak
Pediatrics
(2000) - et al.
An outbreak of hepatitis A among young men associated with having sex in public venues
Commun Dis Public Health
(2001)
Acute hepatitis A virus infection: A review of prognostic factors from 25 years experience in a tertiary referral center
Hepatogastroenterology
Surveillance de l'hepatitis A en France au cours des vingt dernières années: les donnes actuelles ne permettent pas d'estimer la vaux d'incidence
Bul Epidemiol Hebdomadaire
Prevention of hepatitis A through active or passive immunization: Recommendations of the Advisory Committee on Immunization Practices (ACIP)
MMWR Recomm Rep
Evaluation d'un systeme pilote de surveillance pour l'hepatite A, France 2001
Bull Epidemiol Hebdomadaire
The changing epidemiological pattern of hepatitis A in England and Wales
Epidemiol Infect
Hepatitis A, B, and C in Canada. Results from the National Sentinel Health Unit Surveillance System, 1993-1995
Can J Public Health
Prevalence of hepatitis A antibodies in schoolchildren in Catalonia (Spain) after the introduction of universal hepatitis A immunization
J Med Virol
A population-based seroprevalence study of hepatitis A virus using oral fluid in England and Wales
Am J Epidemiol
Seroepidemiology of hepatitis A in the United States
J Infect Dis
Age-specific antibody prevalence to hepatitis A in England: Implications for disease control
Epidemiol Infect
Hepatitis A infection: A seroepidemiological study in young adults in North-East Italy
Eur J Epidemiol
Prevalence of markers for hepatitis A, B and C in the German population. Results of the German National Health Interview and Examination Survey 1998
Eur J Epidemiol
Age-specific prevalence of antibodies to hepatitis A in Santiago, Chile: Risk factors and shift in age of infection among children and young adults
Am J Trop Med Hyg
Incidence-prevalence relationships
The estimation of age-related rates of infection from case notifications and serological data
J Hyg (Lond)
Hepatitis A incidence rate estimates from a pilot seroprevalence survey in Rio de Janeiro, Brazil
Int J Epidemiol
Cited by (0)
This work was partially supported by a grant from the Fondo de Investigaciones Sanitarias, Instituto de Salud Carlos III (Red de Centros de Epidemiología y Salud Pública).