This report briefly describes an explosive outbreak of exanthematous illness, apparently caused by ECHO 9 virus. The outbreak was characterized by three features: (1) It was traced to a primary exposure at a child's birthday party. (2) In contrast with other outbreaks, the distribution of the rash was rather unusual, in that the rash often originated and usually occurred in the highest concentration on the buttocks. (3) There were no obvious signs of meningeal or encephalitic involvement.
Epidemiological and Clinical Observations
Children from 10 families gathered to celebrate the birthday of a child at the home of his grandmother. There were 14 children present, aged 22 months to 31/2 years. The mothers from each family also attended the party, as did one father who was the photographer for the occasion.The party, held on May 16, 1958, brought together families whose homes are located in widely scattered areas of metropolitan