Epidemics of tuberculosis in Canada in the sixties.

Data on 24 localized tuberculosis epidemics occurring in Canada from January 1960 to March 1965 have been analyzed. In a population of about 13,000 at some degree of risk 308 new cases of active tuberculosis occurred-an incidence of 2.3%. In individual outbreaks, however, the incidence was as high as 31%. Epidemics occurred under a wide variety of circumstances-in schools, homes, communities, an army camp and a hockey team. Detected source cases included parents, school teachers, a cook, a hired man and a "den mother".Because of the involvement of children, about four out of 10 new active cases were primary tuberculosis. Approximately two out of 10 were moderately or far advanced pulmonary cases. The findings suggest the need to reconsider BCG vaccination of the younger age group as a means of raising the level of herd immunity.