Changing pattern of hepatitis a virus epidemiology in an area of high endemicity

Continuous assessment of hepatitis A virus (HAV) seroepidemiology is a useful tool to control the risk of infection.

This study aimed to evaluate the changing patterns of anti-HAV seroprevalence in a population,which isgenerally considered to be anarea ofhigh endemicity.

Overall, the results of 3349 sera collected during the period 2005-2008 from patients attending the University Hospital of Cagliari, Italy were studied; their mean age was 52.7 years, (s + 16.22). Patients with liver disease were excluded from the study. Age specific seroprevalence results were compared with those observed in similar previous studies carried out in the same area.

The overall prevalence of anti-HAV was 74.6% with consistently lower values in subjects younger than 40 years (17.5%; P < 0.0001) particularly in those under 30 years of age (8.9%, CI 5.8-11.9). A significant declining trend in age specific seroprevalence has been foundin people under 30 years;61% in 1988, 33% in 1995 and 8.9% in 2005-2008.

Our findings show that a significant decline inherd immunity has occurred in the last 20 years as a consequence of lower HAV circulation due to improvementsin socio-economical and hygienic conditions. Adolescents and young adults are becoming increasingly susceptible to HAV infections, as recent outbreaks of acute HAV hepatitis have occurred. Persistent environmental monitoring and the implementation of prevention measures must be considered in order to contain the risk related to this epidemiological shift.