Search for persistent epizootic Venezuelan encephalitis virus in Guatemala, El Salvador and Nicaragua during 1970-1975.
Abstract: Evidence was sought during 1970-1975 of persistence of equine-virulent Venezuelan encephalitis (VE) virus in regions of Central America that were heavily involved in the epidemic-equine epizootic of 1969. (a) Four sentinel horses were exposed in an arid, upland region of the Atlantic drainage of Guatemala during August-October 1970, but no horse became infected. (b) The epicenter region of the 1969 outbreak, in southwestern Guatemala and southwestern El Salvador, was studied during July 1970-February 1974; no antibody developed in sentinel horses, sentinel hamsters did not die, mosquitoes yielded no virus, wild rats had no detectable VE virus HI antibody. Unexplained decreases in populations of wild terrestrial mammals possibly limited maintenance of VE virus. However, mosquitoes were plentiful and present in the same species composition found at a focus of enzootic VE virus about 35 km northwest of the epicenter region. (c) In studies at two Guatemalan ranches near the epicenter, where horses died in 1969, VE viruse infected sentinel horses along one of three lakes on one ranch during the wet season of 1972 but not during the dry or wet seasons of 1973; the titers of neutralizing antibodies in these four horses were higher against an enzootic strain of VE virus than against an epizootic strain. During 1970 and 1971, VE virus was isolated from sentinel hamsters exposed at a marsh on the other ranch, but Vero plaque characteristics were those of enzootic VE virus. (d) The only epizootic activity of VE virus discovered in Central America in 1970-1975 occurred in Nicaragua between April and June 1972. Several hundred horses died, and N antibody, like that engendered by epizootic virus, was found in two young, unvaccinated horses. Whether this represented persistence of epizootic VE virus or reintroduction of virus is unknown.
Publication Date: 1976-07-01 PubMed ID: 7139DOI: 10.1093/oxfordjournals.aje.a112274Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- U.S. Gov't
- Non-P.H.S.
- Diagnosis
- Disease control
- Disease Diagnosis
- Disease Etiology
- Disease Management
- Disease Outbreaks
- Disease Prevalence
- Disease Surveillance
- Disease Treatment
- Epidemiology
- Equine Diseases
- Equine Health
- Horses
- Infectious Disease
- Public Health
- Vector-borne disease
- Veterinary Medicine
- Veterinary Research
- Veterinary Science
- Virology
- Virus
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
This research paper investigates the persistence of Venezuelan encephalitis (VE) virus, which affects horses, in Central America from 1970-1975 after a major outbreak in 1969.
Objective and Research Methods
- The main goal of this study was to find evidence of the continued presence of a virulent, or severe, form of the Venezuelan encephalitis (VE) virus in areas of Central America that were heavily impacted by a major epidemic in 1969. The study was conducted from 1970 to 1975.
- Several different methods were used in this research, including exposing sentinel (disease indicator) horses to potential infections, studying the region where the outbreak began, investigating two ranches where horses had died in 1969, and observing VE virus activity in Nicaragua.
Findings
- The researchers found no evidence of infection in sentinel horses exposed in Guatemala during August-October 1970.
- The investigation in the epicenter of the outbreak, in southwestern Guatemala and El Salvador, produced no evidence of VE virus presence. Horses didn’t develop antibodies, sentinel hamsters didn’t die, mosquitoes carried no virus, and wild rats didn’t carry VE virus antibodies.
- At ranches near the outbreak’s epicenter where horses died in 1969, the virus infected sentinel horses only once during the wet season in 1972. These horses produced higher neutralizing antibodies against a less severe strain of the VE virus.
- The only severe VE virus activity discovered in Central America between 1970 and 1975 occurred in Nicaragua in 1972 where several hundred horses died.
Interpretation and Conclusion
- The research found limited evidence of VE virus persistence. This may have been influenced by unexplained decreases in populations of wild terrestrial mammals, which could help maintain the virus.
- While mosquitoes in the region were plentiful and were of the same species found at a focus of less severe VE virus, they did not yield any virulent virus.
- In Nicaragua, an outbreak in 1972 could have been the result of virus persistence or reintroduction, but this is unknown.
Cite This Article
APA
Scherer WF, Ordonez JV, Dickerman RW, Navarro JE.
(1976).
Search for persistent epizootic Venezuelan encephalitis virus in Guatemala, El Salvador and Nicaragua during 1970-1975.
Am J Epidemiol, 104(1), 60-73.
https://doi.org/10.1093/oxfordjournals.aje.a112274 Publication
Researcher Affiliations
MeSH Terms
- Adolescent
- Adult
- Animals
- Antibodies, Viral / analysis
- Child
- Cricetinae
- Culicidae / microbiology
- Disease Reservoirs
- El Salvador
- Encephalitis Virus, Venezuelan Equine / isolation & purification
- Encephalomyelitis, Equine / microbiology
- Encephalomyelitis, Venezuelan Equine / immunology
- Encephalomyelitis, Venezuelan Equine / microbiology
- Encephalomyelitis, Venezuelan Equine / transmission
- Female
- Guatemala
- Hemagglutination Inhibition Tests
- Horses
- Humans
- Immunization
- Male
- Middle Aged
- Nicaragua
- Seasons
- Swine
Citations
This article has been cited 3 times.- Deardorff ER, Weaver SC. Vector competence of Culex (Melanoconion) taeniopus for equine-virulent subtype IE strains of Venezuelan equine encephalitis virus. Am J Trop Med Hyg 2010 Jun;82(6):1047-52.
- Deardorff ER, Forrester NL, Travassos-da-Rosa AP, Estrada-Franco JG, Navarro-Lopez R, Tesh RB, Weaver SC. Experimental infection of potential reservoir hosts with Venezuelan equine encephalitis virus, Mexico. Emerg Infect Dis 2009 Apr;15(4):519-25.
- Brault AC, Powers AM, Medina G, Wang E, Kang W, Salas RA, De Siger J, Weaver SC. Potential sources of the 1995 Venezuelan equine encephalitis subtype IC epidemic. J Virol 2001 Jul;75(13):5823-32.
Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
