GENETIC DIVERSITY OF WILD-TYPE MEASLES VIRUSES - IMPLICATIONS FOR GLOBAL MEASLES ELIMINATION PROGRAMS

Wild-type measles viruses have been divided into distinct genetic grou ps according to the nucleotide sequences of their hemagglutinin and nu cleoprotein genes. Most genetic groups have worldwide distribution; ho wever, at least two of the groups appear to have a more limited circul ation. To monitor the transmission pathways of measles virus, we obser ved the geographic distribution of genetic groups, as well as changes in them in a particular region over time. We found evidence of interru ption of indigenous transmission of measles in the United States after 1993 and identified the sources of imported virus associated with cas es and outbreaks after 1993. The pattern of measles genetic groups pro vided a means to describe measles outbreaks and assess the extent of v irus circulation in a given area. We expect that molecular epidemiolog ic studies will become a powerful tool for evaluating strategies to co ntrol, eliminate, and eventually eradicate measles.