Veterinary pathology2001; 38(4); 451-456; doi: 10.1354/vp.38-4-451

Clinical, pathologic, immunohistochemical, and virologic findings of eastern equine encephalomyelitis in two horses.

Abstract: Natural eastern equine encephalitis alphavirus (EEEV) infection was diagnosed in two adult horses with anorexia and colic, changes in sensorium, hyperexcitability, and terminal severe depression. Myocardium, tunica muscularis of stomach, intestine, urinary bladder, and spleen capsule had coagulative necrosis and perivascular lymphocytic infiltrate. Central nervous system (CNS) lesions were diffuse polioencephalomyelitis with leptomeningitis characterized by perivascular T lymphocyte cuffing, marked gliosis, neuronophagia, and multifocal microabscesses. Lesions were more prominent within cerebral cortex, thalamus, hypothalamus, and mesencephalon. EEEV was identified in the cytoplasm of cardiac myocytes and smooth muscle cells of spleen, stomach, intestine, urinary bladder, blood vessels, and dendritic cells. In the CNS, EEEV-positive cells included neurons, astrocytes, oligodendrocytes, microglia, and neutrophils. EEEV was isolated from the CNS of both horses. The detailed description of the encephalic and spinal EEEV localization and the findings of EEEV in extraneural tissues contribute to the understanding of this important multisystemic zoonotic disease.
Publication Date: 2001-07-27 PubMed ID: 11467481DOI: 10.1354/vp.38-4-451Google Scholar: Lookup
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The research article is about the study of a virus called Eastern Equine Encephalitis Alphavirus (EEEV) in two adult horses which showed symptoms such as loss of appetite, colic, changes in awareness, hyperexcitability, and extreme depression before death. A detailed account was provided about where in the body of the horses the EEEV was found along with the consequent tissue damage it caused.

Objective of the study

The research was focused on diagnosing the Eastern Equine Encephalitis Alphavirus (EEEV) in two adult horses. Symptoms like anorexia, colic, changes in sensorium, hyperexcitability, and terminal severe depression led the researchers to suspect EEEV infection.

Documentation of the findings

  • The researchers conducted post-mortem examinations and noted coagulative necrosis (cell death) and perivascular lymphocytic infiltrate (immune cells around the blood vessels) in various organs such as the myocardium (heart muscle), stomach, intestines, urinary bladder, and spleen.
  • Specific observations were made on central nervous system lesions, considering the virus primarily targets the nervous system. The presence of diffuse polioencephalomyelitis with leptomeningitis was a clear sign of EEEV infection.
  • The virus was identified within cells of various tissues, including the heart, stomach, intestines, blood vessels, urinary bladder, kidneys and dendritic cells, an important group of immune cells.

Involvement of the Central Nervous System (CNS)

  • In the central nervous system, the EEEV-positive cells included neurons, astrocytes, oligodendrocytes, microglia, and neutrophils, reinforcing the assumption of the virus targeting CNS.
  • In addition to the physical symptoms observed, the presence of EEEV identified in these cells within the CNS further confirmed infection.
  • The EEEV strain was successfully isolated from the central nervous system of both horses, which will aid future research and treatment methods.

Overall importance of the study

  • This research enriches our understanding of EEEV, an important zoonotic disease – diseases that are transferred from animals to humans.
  • The detailed account of the precise location of EEEV in the body and the associated tissue damage contributes significantly to ongoing efforts to combat such diseases.

Cite This Article

Del Piero F, Wilkins PA, Dubovi EJ, Biolatti B, Cantile C. (2001). Clinical, pathologic, immunohistochemical, and virologic findings of eastern equine encephalomyelitis in two horses. Vet Pathol, 38(4), 451-456.


ISSN: 0300-9858
NlmUniqueID: 0312020
Country: United States
Language: English
Volume: 38
Issue: 4
Pages: 451-456

Researcher Affiliations

Del Piero, F
  • School of Veterinary Medicine, University of Pennsylvania, Department of Pathobiology, Kennett Square, USA.
Wilkins, P A
    Dubovi, E J
      Biolatti, B
        Cantile, C

          MeSH Terms

          • Animals
          • Encephalitis Virus, Eastern Equine / isolation & purification
          • Encephalomyelitis, Eastern Equine / pathology
          • Encephalomyelitis, Eastern Equine / virology
          • Fatal Outcome
          • Horse Diseases / pathology
          • Horse Diseases / virology
          • Horses
          • Immunohistochemistry / veterinary
          • Kidney / pathology
          • Kidney / virology
          • Male
          • Myocardium / pathology


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