[Is there a shift in the epidemiology of hepatitis A in Mexican children?].

Introduction: Twenty years ago, prevalence of Hepatitis A in Mexican children was 90%.
Objective: To describe a shift in the prevalence of Hepatitis A virus (HAV) infection and to demonstrate an increment in the age at the first contact with HAV, in a sample of Mexican children.
Material and Methods: Reports of antiviral serologic studies collected from 1991 to 2005 from patients attending a pediatric hospital, were reviewed, and those with IgM anti-HAV positive in serum were selected. Age at the moment of acute infection was analyzed. Additionally, a serological survey searching IgG anti-HAV was made in a group of HAV unvaccinated children.
Results: From 1708 determinations of IgM, 221 were positive (13%). According to the year of report, five groups were constituted. Mean age by group was: 1991-1993 of 6.4 years, 1994-1996 of 8.0, 1997-1999 of 8.4, 2000-2002 of 8.0 and from 2003-2005 of 10.1 years. In a cohort of 259 unvaccinated children (mean of age 8.59 years), IgG antibodies were detected in 51%.
Conclusion: In the infantile population studied a Hepatitis A epidemiology shift is suggested.