Multiple sclerosis and delayed mumps.

To test the hypothesis that mumps occurs less frequently and later in patients with multiple sclerosis, histories were taken from patients and matched controls by a single observer at a university hospital in Canada, and in the course of domiciliary visits in England. 63 consecutive patients with multiple sclerosis in two neurological practices, and 63 controls matched for age, sex and childhood domicile, together with 29 sibs of English patients were studied. Patients had mumps at an older age (12.3:8.6, p less than 0.04) and less frequently (33/63 vs 60/92, p = 0.08). Multiple sclerosis patients display a partial immunity to mumps, of which the most obvious explanation is a preceding infection by an antigenically related paramyxovirus, that is, by either the Newcastle Disease virus, or parainfluenza.