Immunological study on association between mumps and infantile unilateral deafness.

The incidence of unilateral deafness in primary school children has been reported to be about 0.1%, but the cause of most of these cases has not been clarified, because parents and children themselves cannot recognize the onset of hearing loss occurring in one ear alone. This study was performed to clarify the possibility that mumps causes infantile unilateral deafness. The results were: 1) on dividing a total of 78 cases of infantile unilateral deafness according to age from 3 to 6 years, mumps infection rate in the 4-year-old group was nearly twice that in a randomly selected group; 2) on checking the neutralizing or ELISA IgG test of 31 cases with no history of mumps only, the 4-year-old group demonstrated a positive reaction to mumps more than the randomly selected group did. The above results suggested that unilateral deafness may be caused by asymptomatic mumps infection. To confirm this, we studied 5 infantile cases of sudden hearing loss by means of ELISA IgM antibody test and found a bilateral sudden deafness in children aged 1.9 years, caused by asymptomatic mumps infection.