SSPE and Early Measles Infection
Approximately 46-71% of children who developed SSPE had measles before age 3 years, with the highest risk occurring in those infected before 15 months of age.
Age Distribution of Measles Infection in SSPE Cases
The evidence consistently demonstrates that SSPE disproportionately affects children who contracted measles at very young ages:
In a national registry study of 292 SSPE patients with confirmed measles history, 46% had measles illness before age 2 years 1
A more recent California cohort (1998-2015) found that among 12 SSPE cases with documented measles-like illness, all 12 (100%) had measles prior to 15 months of age 2
A case-control study confirmed that the age at measles infection for children with SSPE was significantly younger than controls who had measles 3
One Turkish case series documented three unvaccinated patients who developed SSPE after measles infections at 3,8, and 30 months of age 4
Clinical Significance of Early Infection
The younger age at measles infection carries profound implications:
Children residing in areas with poor vaccination coverage who contract measles under age 5 years have the highest risk of developing SSPE 5
The incidence of SSPE among California measles cases (1988-1991) was 1:609 for children infected before 12 months of age, compared to 1:1367 for all children under 5 years 2
The latency period between measles infection and SSPE onset averages 7-9.5 years, with SSPE typically diagnosed at a median age of 12 years 2, 1
Prevention Through Vaccination
The only effective prevention strategy remains measles vaccination:
Measles vaccination has essentially eliminated SSPE in highly vaccinated populations 6, 7
The risk of SSPE following measles vaccination (0.5-1.1 cases per million) is substantially lower than following natural measles infection (5.2-9.7 cases per million) 1
Protection of unvaccinated infants requires avoidance of travel to endemic areas or early vaccination at age 6-11 months prior to travel 2