Postepizootic persistence of Venezuelan equine encephalitis virus, Venezuela.
Five years after the apparent end of the major 1995 Venezuelan equine encephalitis (VEE) epizootic/epidemic, focal outbreaks of equine encephalitis occurred in Carabobo and Barinas States of western Venezuela. Virus isolates from horses in each location were nearly identical in sequence to 1995 isolates, which suggests natural persistence of subtype IC VEE virus (VEEV) strains in a genetically stable mode. Serologic evidence indicated that additional outbreaks occurred in Barinas State in 2003. Field studies identified known Culex (Melanoconion) spp. vectors and reservoir hosts of enzootic VEEV but a dearth of typical epidemic vectors. Cattle serosurveys indicated the recent circulation of enzootic VEEV strains, and possibly of epizootic strains. Persistence of VEEV subtype IC strains and infection of horses at the end of the rainy season suggest the possibility of an alternative, cryptic transmission cycle involving survival through the dry season of infected vectors or persistently infected vertebrates.
Navarro
Juan-Carlos
JC
Universidad Central de Venezuela, Caracas, Venezuela.
Medina
Gladys
G
Vasquez
Clovis
C
Coffey
Lark L
LL
Wang
Eryu
E
Suárez
Alexander
A
Biord
Hernán
H
Salas
Marlene
M
Weaver
Scott C
SC
D000818:Animals; D002417:Cattle; D009033:Culicidae / Q000821:virology; D048293:Didelphis / Q000821:virology; D004196:Disease Outbreaks; D004197:Disease Reservoirs / Q000821:virology; D004666:Encephalitis Virus, Venezuelan Equine / Q000235:genetics / Q000302:isolation & purification*; D004685:Encephalomyelitis, Venezuelan Equine / Q000097:blood / Q000453:epidemiology* / Q000821:virology*; D006736:Horses / Q000097:blood / Q000821:virology*; D006801:Humans; D051189:Murinae / Q000821:virology; D010802:Phylogeny; D012621:Seasons; D018571:Sentinel Surveillance; D014687:Venezuela / Q000453:epidemiology