In this report of the Subacute Sclerosing Panencephalitis (SSPE) Registry during 1960 through 1970, the findings indicate a 50% relationship of SSPE to early (under 2 years of age) measles infection. The frequency of SSPE is one per million, and a majority of the patients reside in the southeastern part of the United States.
Jabbour JT, Duenas DA, Sever JL, Krebs HM, Horta-Barbosa L. Epidemiology of Subacute Sclerosing Panencephalitis (SSPE)A Report of the SSPE Registry. JAMA. 1972;220(7):959-962. doi:10.1001/jama.1972.03200070051006