The epidemiology of subacute sclerosing panencephalitis in England and Wales 1990-2002

Aim: To assess the impact of measles/mumps/rubella (MMR) vaccine on the epidemiology of subacute sclerosing panencephalitis (SSPE) in England and Wales. Methods: Cases of SSPE resident in England and Wales with onset between 1990 and 2002 were reviewed. Results: A total of 47 cases were identified, 31 male and 16 female. There was an average annual decline of 14% in SSPE onset over the period, consistent with the decline in notified measles over the last 20 years. A history of measles was present in 35 (median age 1.3 years), the most recent recorded date being 1994; the interval from measles to onset of SSPE ranged from 2.7 to 23.4 years. Four children with a history of receipt of a measles containing vaccine were reported not to have had measles; two of these cases had a brain biopsy, and nucleotide sequence data confirmed wild measles infection. Brain biopsy specimens from a further three cases with a history of measles, of whom two had also had a history of vaccination, showed wild-type strain. Conclusion: The prevention of endemic circulation of measles virus in England and Wales through the high coverage achieved with MMR vaccine, together with the measles/rubella vaccination campaign of 1994, has resulted in the near elimination of SSPE. However, the recent decline in MMR vaccine coverage, with the associated increase in localised measles outbreaks and cases in young infants, is of concern. It underlines the importance of maintaining high vaccine coverage in order to protect indirectly those most vulnerable to SSPE, namely infants too young to be vaccinated.