Epidemic Venezuelan Equine Encephalitis in North America in 1971: Vertebrate Field Studies1

Abstract

Epidemic Venezuelan equine encephalitis in North America in 1971: vertebrate field studies. Am J Epidemiol 101:36-50, 1975.-In June 1971, epidemic Venezuelan equine encephalitis (VEE) invaded the lower Rio Grande Valley in south Texas. The Boca Chica area of Cameron County was selected as a study site to investigate vertebrate involvement in the natural cycle of epidemic VEE on the basis of considerable evidence of VEE virus activity there in equines, humans, and mosquito vectors. Only one VEE virus isolation was made from 4739 wild and domestic non-equine vertebrates, although numerous equine and human VEE virus isolations were made in concurrent studies. Serologic studies indicated that VEE virus activity was far greater in large domestic animals than in wild birds, wild mammals, or reptiles. Apparently epidemic VEE virus failed to establish itself in a wild vertebrate cycle in south Texas, since VEE antibody was found only in rabbits in 1972. Eventual cessation of VEE transmission in south Texas has been attributed 1) to the elimination of equines as a source of VEE virus by death, naturally acquired antibodies, or vaccination, 2) to quarantines, 3) to mosquito control, and 4) to the failure of epidemic VEE virus to become established in the wild vertebrate population. Equines emerge as the most important vertebrate host in the amplification and spread of virus during an epidemic of VEE.

Venezuelan Equine Encephalitis Virus Infection of Cotton Rats

“…This resistance is little studied and poorly understood, yet it might provide insight into improved treatments for arbovirus infections in humans. Our findings may also have implications for VEEV ecology, especially in the event of virus introduction into a nonenzootic region, as occurred during the 1971 Texas VEEV epizootic ( 38 , 39 ). During such a scenario, virus-induced deaths might deplete cotton rat populations, depending on the VEEV transmission levels and the length of the outbreak.…”

Experimental Infection of Potential Reservoir Hosts with Venezuelan Equine Encephalitis Virus, Mexico

“…Evidence of similar broad host ranges of VEEV has been found in coastal Guatemala, where 7 genera of terrestrial mammals and 11 species of birds had VEEV-specifi c antibodies (19). After the 1971 epidemic of VEEV-IAB that started in Central America and reached southern Texas, extensive fi eld studies were conducted to determine whether the virus would or could establish a new enzootic focus (20). In that study, mammals of 10 genera had VEEV-specifi c antibodies.…”

Human-like antibodies neutralizing Western equine encephalitis virus

“…10 These alphaviruses can spread to the human central nervous system (CNS), causing symptoms ranging from mild febrile reactions to encephalitis, often resulting in permanent, fatal neurological damage. The severity of the illness depends on the virus strain, the age of the patient, the dose and the route of infection 9 , 11 - 20 . WEEV/EEEV and VEEV have caused epidemics in North, Central and South America.…”