Subacute sclerosing panencephalitis in Italy. An epidemiological study.

An epidemiological inquiry in Italy led to the collection of 207 cases of subacute sclerosing panencephalitis (SSPE) with onset during the decade 1972-1981, with a mean incidence rate of 0.37 cases per year per million total population (CYMTP) and 1.24 cases per year per million young population aged 0-19 years (CYMYP). A striking difference was found among the 20 Italian regions, with a minimum of no cases in three regions, and a maximum incidence of 2.46 CYMTP (6.67 CYMYP) in Sardinia. The male/female ratio was 1.8/1. The mean age at SSPE onset was 10.6 (+/- 4.0) years in Italy, and was significantly lower in Sardinia (8.8 +/- 2.8). The mean age of measles was 2.8 +/- 1.7 years (in 106 cases), significantly lower than the mean age of measles in the general population. Moreover, the age of measles was significantly lower in males than in females, and this could represent a factor contributing to the higher SSPE incidence in males. The interval between measles and SSPE onset was significantly lower in Sardinia (mean 5.6 +/- 2.5 years). In Italy, as in other Mediterranean countries, SSPE incidence is higher than expected and unevenly distributed, suggesting that environmental factors play a role.