Emergence of a new epidemic/epizootic Venezuelan equine encephalitis virus in South America.
One of the most important questions in arbovirology concerns the origin of epidemic Venezuelan equine encephalitis (VEE) viruses; these viruses caused periodic, extensive epidemics/epizootics in the Americas from 1938-1973 (reaching the United States in 1971) but had recently been presumed extinct. We have documented the 1992 emergence of a new epidemic/epizootic VEE virus in Venezuela. Phylogenetic analysis of strains isolated during two outbreaks indicated that the new epidemic/epizootic virus(es) evolved recently from an enzootic VEE virus in northern South America. These results suggest continued emergence of epizootic VEE viruses; surveillance of enzootic viruses and routine vaccination of equines should therefore be resumed.
Rico-Hesse
R
R
Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, CT 06520, USA.
Weaver
S C
SC
de Siger
J
J
Medina
G
G
Salas
R A
RA
D000818:Animals; D005075:Biological Evolution; D004666:Encephalitis Virus, Venezuelan Equine / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D004685:Encephalomyelitis, Venezuelan Equine / Q000453:epidemiology / Q000662:veterinary / Q000821:virology*; D006734:Horse Diseases / Q000453:epidemiology / Q000821:virology; D006736:Horses; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D013020:South America; D013045:Species Specificity; D014687:Venezuela / Q000453:epidemiology