Printed in Great Britain Measles Epidemiology in Italy

In preparation for a mass vaccination programme, the immune status with regard to measles was determined in over 8300 unvaccinated children aged 0-13 years, residing in eight Italian cities with different socioeconomic situations and geographical locations. The age corresponding to the 50 % prevalence of immunes appeared to be intermediate (2.9-5.5 years) between that reported for industrialized (6-7 years) and developing countries (1-2 years). The 50 % prevalence of natural immunity was reached at an earlier age in southern cities in which poorer socioeconomic and hygienic conditions prevailed; the earlier occurrence of measles in these areas was confirmed by a more detailed serological study of children in the first 24 months of life. For children aged 2-13 years, serological results showed that the history of measles reported by parents on questionnaires gave high positive predictive values (over 85%). Our seroepidemiological study shows that, on the basis of the ages of 25 and 75 % prevalence of immunes, the target population for a mass immunization programme in Italy can be assumed to be aged from 12 months to 7 years. However, special attention should be given to the poorest areas, especially in southern Italy, where measles occurs earlier and can be particularly severe. Knowledge of the distribution by age of the prevalence of natural immunity to measles in a country is useful to determine the target population for an effective mas