Risk of SSPE Following Measles Infection at Age 6
Yes, there is significant risk of developing SSPE if a child catches measles at age 6, with an estimated incidence of approximately 4-11 per 100,000 measles cases, and this risk persists regardless of the age at which measles infection occurs. 1, 2
Understanding the Risk Magnitude
The claim that measles after age 5 carries negligible SSPE risk is definitively false according to the Advisory Committee on Immunization Practices. 2 While the highest risk occurs in children infected before age 5 (particularly under 2 years), children infected at age 6 remain at substantial risk for this invariably fatal complication. 1, 3
Specific Risk Data:
- Overall SSPE incidence: 4-11 per 100,000 measles cases 1, 2
- Higher estimates from California surveillance: 1 in 1,367 for children under 5 years 4
- The risk exists at all ages of measles infection, though it decreases with older age at infection 3
Clinical Timeline and Presentation
SSPE typically manifests 6-8 years after the initial measles infection, with onset generally between ages 5-15 years. 2 For a child infected at age 6, symptoms would most likely appear around ages 12-14 years. 4
Disease Progression:
- Insidious onset with personality changes and declining intellectual performance 5
- Progressive mental deterioration, seizures, and myoclonic jerks 5, 1
- Characteristic 1:1 relationship between EEG periodic complexes and myoclonic jerks 5
- Motor deterioration, coma, and death 1
- The disease is invariably fatal 1, 6
Critical Prevention Message
Measles vaccination is the only effective prevention strategy for SSPE, and this remains true regardless of the age at which measles infection might occur. 5, 1, 2 The CDC definitively states that MMR vaccine does not cause SSPE; rather, vaccination prevents it by preventing measles infection itself. 5, 1
Vaccination Recommendations:
- Two doses of MMR vaccine: first at 12-15 months, second at 4-6 years 2
- In high-risk areas, administer the first dose at exactly 12 months rather than waiting 2
- Catch-up vaccination for unvaccinated adolescents and adults born after 1957 2
- Vaccination has essentially eliminated SSPE in highly vaccinated populations 5, 1, 2
Important Clinical Caveats
The latency period between measles infection and SSPE onset averages 9.5 years (range 2.5-34 years), meaning clinicians must maintain awareness of SSPE even in older patients without specific documented measles history. 4 Males are affected 2.4 times more frequently than females. 4
Diagnostic Considerations:
- Detection of intrathecal synthesis of measles-specific antibodies in CSF is crucial for diagnosis 5
- EEG reveals well-defined periodic complexes 5
- Consider PCR testing of CSF for measles virus RNA 5
- Look for oligoclonal bands in CSF with immunoblotting against measles virus proteins 5
Treatment Reality
There is no cure for SSPE. 3 Treatment focuses on supportive care, with seizures and abnormal movements potentially responding to carbamazepine. 3 Intrathecal ribavirin has been attempted with limited success. 5, 1 Most affected children progress to a vegetative state followed by death. 6