Hepatitis A shifting epidemiology in Latin America.

In the past, Latin America was considered to be an area of high endemicity for hepatitis A virus (HAV) infection, with most people infected in early childhood. A seroepidemiological study was recently undertaken in six countries to determine whether this pattern has changed. The highest seroprevalence of antibodies to HAV (anti-HAV) was found in Mexico and the Dominican Republic. Analysis of the different age groups showed that at age 6-10 years, 30% of children in Chile and 54-55% in Brazil, Venezuela and Argentina had been infected, compared with almost 70% in Mexico and 80% in the Dominican Republic. At age 11-15 years, nearly 90% in Mexico and 91% in the Dominican Republic had been infected, compared with 54% in Argentina, 62% in Venezuela, 60% in Brazil and 70% in Chile. By age 31-40 years, over 80% of the populations in all six countries had been exposed to HAV. In all of the countries except Brazil and Venezuela, the seroprevalence of anti-HAV was significantly higher in females than in males. In Mexico, Argentina and Brazil, anti-HAV seroprevalence was significantly higher in the low socioeconomic groups than in the middle/high socioeconomic groups. The results show that there has been a shift from high to medium endemicity of HAV infection throughout Latin America, which may result in more clinical cases in adolescents and adults and a greater potential for outbreaks. The vaccination strategy for hepatitis A should thus be reviewed.