Impact of measles in Canada.

The reported incidence of measles in Canada in 1981 was reduced 97% from the average annual rates during the prevaccine period, 1949-1958. Throughout recent years the age-specific incidence of reported cases of measles has remained highest in the group five to nine years of age, but there has been a definite increase in the proportion of cases of measles in persons greater than 10 years of age. During the extensive measles epidemic in Alberta in 1979, a high proportion of the reported cases occurred in adolescents and young adults previously vaccinated with killed vaccine, and the majority of these developed atypical measles syndrome. In Canada, from five to 36 patients per 100,000 population have required hospitalization annually for complications due to measles over the past 16 years. Measles-related deaths have declined in a pattern similar to that for reported incidence. Despite favorable trends in the control of measles in Canada, the social and economic impacts of this disease remain substantial and warrant a nationwide effort to eliminate indigenous infection.