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Emerging infectious diseases2006; 11(12); 1907-1915; doi: 10.3201/eid1112.050533

Postepizootic persistence of Venezuelan equine encephalitis virus, Venezuela.

Abstract: 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.
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Publication Date: 2006-02-21 PubMed ID: 16485478PubMed Central: PMC3367636DOI: 10.3201/eid1112.050533Google Scholar: Lookup
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  • Journal Article
  • Research Support
  • N.I.H.
  • Extramural
  • Research Support
  • Non-U.S. Gov't

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.

The study investigates the occurrences of Venezuelan equine encephalitis virus (VEEV) in specific regions of Venezuela. The research suggests that despite a major outbreak ending in 1995, the virus has been able to naturally persist due to a potential cryptic transmission cycle.

The Research Background

  • The research is focused on the Venezuelan equine encephalitis virus (VEEV), responsible for outbreaks of equine encephalitis, a condition that causes inflammation of the brain in horses.
  • The major outbreak of this virus ended in 1995, but the study reports its re-emergence in Carabobo and Barinas States of western Venezuela five years after.

Findings of the Study

  • By analyzing virus samples from horses in the aforementioned locations, researchers found the strains were almost identical to the ones observed during the 1995 outbreak. This suggests the virus’ persistence in a genetically stable form.
  • Moreover, serologic evidence – evidence from blood tests – revealed that additional outbreaks happened in Barinas State in 2003.
  • The researchers are also pointing to the possibility of a cryptic transmission cycle, through which the virus can survive the dry season by remaining in infected vectors or persistently infected vertebrates.

Detection Methods and Results

  • The study found Culex (Melanoconion) spp., known vectors and reservoir hosts of enzootic VEEV, but noticed a lack of typical epidemic vectors.
  • Cattle serosurveys, which are blood tests conducted on a group of cattle, indicated recent circulation of enzootic VEEV strains, and possibility of epizootic strains alongside.

Implications of the Research

  • The findings suggest that the VEEV subtype IC strains can persist even after a major outbreak has supposedly ended.
  • This highlights the virus’s capacity to continue infecting horses even at the end of the rainy season, suggesting the existence of an unapparent or ‘cryptic’ transmission cycle.
  • The research thus signals the need for ongoing surveillance and countermeasures even after an outbreak’s apparent end, to prevent resurgence and control the spread of the VEEV.

Cite This Article

APA
Navarro JC, Medina G, Vasquez C, Coffey LL, Wang E, Suárez A, Biord H, Salas M, Weaver SC. (2006). Postepizootic persistence of Venezuelan equine encephalitis virus, Venezuela. Emerg Infect Dis, 11(12), 1907-1915. https://doi.org/10.3201/eid1112.050533

Publication

Emerging infectious diseases
ISSN: 1080-6040
NlmUniqueID: 9508155
Country: United States
Language: English
Volume: 11
Issue: 12
Pages: 1907-1915

Researcher Affiliations

Navarro, Juan-Carlos
  • Universidad Central de Venezuela, Caracas, Venezuela.
Medina, Gladys
    Vasquez, Clovis
      Coffey, Lark L
        Wang, Eryu
          Suárez, Alexander
            Biord, Hernán
              Salas, Marlene
                Weaver, Scott C

                  MeSH Terms

                  • Animals
                  • Cattle
                  • Culicidae / virology
                  • Didelphis / virology
                  • Disease Outbreaks
                  • Disease Reservoirs / virology
                  • Encephalitis Virus, Venezuelan Equine / genetics
                  • Encephalitis Virus, Venezuelan Equine / isolation & purification
                  • Encephalomyelitis, Venezuelan Equine / blood
                  • Encephalomyelitis, Venezuelan Equine / epidemiology
                  • Encephalomyelitis, Venezuelan Equine / virology
                  • Horses / blood
                  • Horses / virology
                  • Humans
                  • Murinae / virology
                  • Phylogeny
                  • Seasons
                  • Sentinel Surveillance
                  • Venezuela / epidemiology

                  Grant Funding

                  • R01 AI048807 / NIAID NIH HHS
                  • AI48807 / NIAID NIH HHS

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                  Citations

                  This article has been cited 11 times.
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