Epidemiological events surrounding a paralytic case of poliomyelitis in Sweden.

A case of clinical poliomyelitis occurred in Sweden in January 1977; it was the first indigenous case in Sweden since 1962. This incident was of particular interest as it provided an opportunity to study the spread of virus in a cluster of unvaccinated persons and in individuals more or less fully vaccinated with inactivated vaccine. The patient excreted wild type 2 virus and the same type was isolated from 25 other individuals, all of whom were close contacts of virus excretors. Among the close contacts, 14 of 20 unvaccinated preschool children were found to excrete virus, but excretion was not found in any of the 7 vaccinated children examined.