Epidemiologic studies on Mumps.

Abstract

An intrafamilial serological and virological surveillance of mumps was carried out in Nagoya, a Japanese large city; where urbanization has been in progress rapidly and children are suffering from mumps sporadically nearly all the year around. Fourty five families with sporadic cases of mumps were studied. Of 59 sensitive contacts in the family, 33 suffered from clinically apparent mumps and 24 progressed subclinical infection. Only two of them escaped from the infection after exposure. Subclinical infections were more frequent in younger children. Among 7 sensitive contacts who resulted in subclinical infection after the exposure, 5 children were found to discharge mumps virus. Virus was also isolated from two mothers of the indicator cases, although their serological examinations revealed that they were apparently re-infected persons. It may be possible to postulate that 1) in the families dwelling in the urban area of the city, mumps virus has very high communicability, 2) subclinical infections were more frequent in younger children, 3) subclinically infected and re-infected persons would be sources of virus transmission, as well as mumps patients.