The significance of mumps hemagglutinin inhibition titers in normal populations

Mumps hemagglutination-inhibiting antibodies were clearly related to mumps history in diverse normal populations. A decline in titer of about twofold per decade after infection was observed in prospective and retrospective studies. This decline was such that many persons who had had mumps more than 15 years prior to testing had titers that could not be distinguished from non-immune. There was very little variation in titer over one month. Antibodies against four parainfluenza strains were tested for correlation with the discrepancies that were found between mumps serology and history. No correlation was found to suggest that parainfluenza causes a persistent aberration of mumps titer, but transient aberrations may occur.(Summary)