EMERGENCE OF A NEW EPIDEMIC EPIZOOTIC VENEZUELAN EQUINE ENCEPHALITIS-VIRUS IN SOUTH-AMERICA

One of the most important questions in arbovirology concerns the origi n of epidemic Venezuelan equine encephalitis (VEE) viruses; these viru ses caused periodic, extensive epidemics/epizootics in the Americas fr om 1938-1973 (reaching the United States in 1971) but had recently bee n presumed extinct. We have documented the 1992 emergence of a new epi demic/epizootic VEE virus in Venezuela. Phylogenetic analysis of strai ns isolated during two outbreaks indicated that the new epidemic/epizo otic virus(es) evolved recently from an enzootic VEE, virus in norther n South America. These results suggest continued emergence of epizooti c VEE viruses; surveillance of enzootic viruses and routine vaccinatio n of equines should therefore he resumed.