An outbreak of influenza occurring on the Isthmus of Panama in 1959 is described. Type B influenza viruses, antigenically similar to B/GL/54, were isolated and serological evidence of infection was demonstrated in a high proportion of persons tested. The outbreak began shortly after the opening of schools and the onset of the wet season and it is possible that these factors contributed to the spread of the virus. Tissue culture techniques were found to be practical for the study of influenza in this outbreak.
Present address: Department of Pathology, Peter Bent Brigham Hospital, Boston 15, Massachusetts.