Canada must be alert to threat of imported wild poliovirus, working group says.

Even though the Western Hemisphere is certified as being polio free, countries such as Canada must be alert to the continuing threat posed by the importation of wild poliovirus from polio-endemic regions, according to a report from Canada's Working Group on Polio Eradication and the Laboratory Centre for Disease Control. The working group recommends the maintenance of high immunization-coverage levels and strengthened surveillance activities for polio.