Genotyping of measles virus in Canada: 1979-2002.

Genotyping is an important component of measles surveillance. In this study, we report the genotypes of 30 measles viruses from cases in Canada; 6 of these were collected between 1979 and 1996 and 24 were collected from 1997 through 2002. Many measles virus genotypes were found (C1, C2, D3, D4, D5, D6, D7, D8, E, and H1). These data indicate that the predominant measles virus genotypes detected from 1979 to 1997 in Canada are no longer commonly found. Since the implementation of a routine second dose of measles vaccine and catch-up campaigns in 1996-1997, the wide variety of measles virus genotypes found supports epidemiological data showing that importation of measles is the source of current measles cases in Canada.