Subacute sclerosing panencephalitis: The devastating long-term risk of measles infection in young children

Summary Subacute sclerosing panencephalitis (SSPE) is a fatal, progressive neurodegenerative disease of the central nervous system caused by persistent, mutated measles virus that remains dormant in brain tissue for years after an apparently resolved acute measles infection.  SSPE risk is strongly age-dependent, with infection under age 5 (and especially under 1 year) carrying by far the highest risk. Here is a summary with specifically German data confirming this pattern. Overall SSPE risk Baseline risk after measles infection at any age is generally cited as 4–11 per 100,000 measles cases in well-documented series, though older global estimates range as high as 27.9 per 100,000. The condition typically develops 7–10 years after acute infection, with a mean age of onset around 9 years. Table 1:  Age-dependent SSPE risk Age at measles infection SSPE risk All ages combined 4–11 per 100,000 (~1 in 9,100–15,400) <5 years 1 in 1,700 to 1 in 3,300 <1 year As high as 1 in 609 to 1...