Hepatitis A (HAV) virus infection in children in Argentina. Pilot study

A multicenter serologic study of 3699 children between 6 months and 10 years of age was conducted to determine the infection curve of hepatitis A virus (HAV) in order ultimately to maximize the efficiency of the immunization program in Argentina. Commercially available enzyme immunoassay tests were used to screen for specific HAV antibodies. 45.2% of the children were screened in San Justo 13% in Buenos Aires 26.2% in Rosario 7.3% in Tucuman and 8.4% in Trelew. 1076 children under 10 years of age with clinical cases of acute viral hepatitis A served as controls. The highest proportion of positive results was found in Tucuman (81.4%) followed by San Justo (57.8%) Rosario (46.5%) Trelew (42.0%) and Buenos Aires (29.4%). In all the cities children under 3 years old had the lowest seropositive rates. The proportions positive increased with age in all cases except in Trelew where a peak occurred at 4 years. The overall proportion of those seropositive was 51.56%. No significant variations were observed by sex. Zones with more than 40% of individuals affected by age 5 are considered highly endemic for HAV. In the sample 45.9% were affected by age 5 and 68.0% were affected by age 10. In populations of high endemicity mass vaccination of infants and children is the only strategy capable of preventing recurrent epidemics.