Symptomatic mumps virus reinfections

Although natural mumps virus infection is believed to induce lifelong immunity, our laboratory was confronted with 82 patients who developed mumps‐evoking lesions but exhibited serological evidence of a booster immune response, namely a rise or a high titer of virus‐specific IgG, without IgM. In order to provide arguments favoring the existence of recurrent mumps attacks, the age, symptomatology, and humoral response of these patients (group 1) were compared to that of 82 randomly selected true primary infected patients (group 2), 10 parainfluenza virus‐infected patients (group 3), and 20 noninfected mumps‐immune subjects (group 4), Enzyme‐linked immunosorbent assay (ELISA) procedures with different viral antigenic preparations were used for determination of specific IgM, IgA, IgG, IgG subclasses, and IgG avidity. The patients of group 1, older than those of group 2 (28 vs. 10 years, P