Abstract
The prevalence of naturally acquired mumps and measles antibodies was determined in unvaccinated children (newborn to 15 years of age) in Saudi Arabia, a developing country with distinct socioeconomic situation, hygienic conditions and geographic location. The age corresponding to the 50 per cent prevalence of measles immunity was between 3 and 4 years compared to 6–7 years for developed, and 1–2 years for other developing nations. Acquisition of antibodies to mumps was found to be at a somewhat later age with a 50 per cent antibody prevalence rate at 5 years and peak levels by the age of 9. The target population for measles and mumps immunization is thus identified. Eighteen cases in children aged 3–14 years clinically suspected of subacute sclerosing panencephalitis (SSPE) were serologically investigated so as to determine simultaneously the level of antibodies to measles in the cerebrospinal fluid (CSF) and serum. Raised titres of measles specific antibodies in CSF as well as in serum were detected in 50 per cent of the cases thus providing a serological confirmation.