Venezuelan Equine Encephalitis Clinical Presentation

  • Author: Robert W Derlet, MD; Chief Editor: Burke A Cunha, MD   more...
 
Updated: Jul 18, 2011
 

History

Patients give a history of exposure to mosquitoes in an area endemic for Venezuelan equine encephalitis. Suspect Venezuelan equine encephalitis and dengue fever in anyone with a febrile illness who has recently traveled in rural areas of Central America or tropical South America.

Subclinical infections occur, but the incidence is unknown. Venezuelan equine encephalitis virus infection manifests as influenzalike symptoms approximately 1-6 days after infection.

Typical initial symptoms of infection include the acute onset of a severe headache with or without associated photophobia, chills, malaise, fever, myalgia, lumbosacral pain, nausea, vomiting, and prostration. Fever may abate in a few days, followed by recrudescence the following day. These initial symptoms may be followed by diarrhea and a sore throat.

Most Venezuelan equine encephalitis virus infections in humans are relatively mild, with symptoms lasting 3-5 days.

Children are at particular risk to progress to clinical CNS involvement, especially encephalitis. Symptoms of CNS involvement include disorientation, somnolence, nuchal rigidity, convulsions, inappropriate antidiuretic hormone (ADH) secretion, paralysis, coma, and death.

Most persons have resolution of symptoms after 5 days; however, a subset of infected persons may remain symptomatic for as long as 2 weeks.

Maternal infection may result in fetal demise or abortion. Congenital infection with CNS malformations has been reported.

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Physical Examination

In humans, fever is the most common physical finding of Venezuelan equine encephalitis virus infection. Pharyngitis, conjunctival congestion, facial flushing, and, rarely, lymphadenopathy are among the sparse physical findings found in mild forms of Venezuelan equine encephalitis. Some patients may progress to exhibit somnolence, photophobia, and mild confusion.

The few patients with Venezuelan equine encephalitis who develop severe neurologic compromise develop significant physical findings, including nuchal rigidity, stupor, delirium, coma, nystagmus, cranial nerve palsies, pathologic reflexes, ataxia, and spastic paralysis. Tremors, abnormal movement disorders, and visual field defects are uncommon.

In equines, signs of infection, including fever, tachycardia, anorexia, and depression, usually appear approximately 2 days after infection. Encephalitis develops in some of these animals within 5-10 days of infection. The animals may show signs of circling, ataxia, and hyperexcitability. Death usually occurs approximately 1 week after infection. The development of encephalitis in equines is related to the magnitude of viremia.

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Contributor Information and Disclosures
Author

Robert W Derlet, MD  Professor of Emergency Medicine, University of California at Davis School of Medicine; Chief Emeritus, Emergency Department, University of California at Davis Health System

Robert W Derlet, MD is a member of the following medical societies: American Academy of Emergency Medicine, American Association for the Advancement of Science, Infectious Diseases Society of America, Society for Academic Emergency Medicine, and Wilderness Medical Society

Disclosure: Nothing to disclose.

Coauthor(s)

Iris Reyes, MD  Associate Professor of Clinical Emergency Medicine, Advisory Dean, Office of Student Affairs, University of Pennsylvania School of Medicine

Iris Reyes, MD is a member of the following medical societies: American College of Emergency Physicians

Disclosure: Nothing to disclose.

Sarah M Perman, MD  Resident, Department of Emergency Medicine, University of Pennsylvania Health Systems

Sarah M Perman, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Emergency Physicians, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

John R Richards, MD, FAAEM  Professor of Emergency Medicine, University of California at Davis School of Medicine

John R Richards, MD, FAAEM is a member of the following medical societies: American Academy of Emergency Medicine and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Suzanne Moore Shepherd, MD, MS, DTM&H, FACEP, FAAEM  Associate Professor, Education Officer, Department of Emergency Medicine, Hospital of the University of Pennsylvania; Director of Education and Research, PENN Travel Medicine

Suzanne Moore Shepherd, MD, MS, DTM&H, FACEP, FAAEM is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American Society of Tropical Medicine and Hygiene, International Society of Travel Medicine, Society for Academic Emergency Medicine, and Wilderness Medical Society

Disclosure: Nothing to disclose.

William H Shoff, MD, DTM&H  Director, PENN Travel Medicine, Associate Professor, Department of Emergency Medicine, Hospital of the University of Pennsylvania

William H Shoff, MD, DTM&H is a member of the following medical societies: American College of Physicians, American Society of Tropical Medicine and Hygiene, International Society of Travel Medicine, Society for Academic Emergency Medicine, and Wilderness Medical Society

Disclosure: Glaxo Smith Kline None None; Glaxo Smith Kline Honoraria Speaking and teaching

Specialty Editor Board

Jerry L Mothershead, MD  Medical Readiness Consultant, Medical Readiness and Response Group, Battelle Memorial Institute; Advisor, Technical Advisory Committee, Emergency Management Strategic Healthcare Group, Veteran's Health Administration; Adjunct Associate Professor, Department of Military and Emergency Medicine, Uniformed Services University of the Health Sciences

Jerry L Mothershead, MD is a member of the following medical societies: American College of Emergency Physicians and National Association of EMS Physicians

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD  Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

John L Brusch, MD, FACP  Assistant Professor of Medicine, Harvard Medical School; Consulting Staff, Department of Medicine and Infectious Disease Service, Cambridge Health Alliance

John L Brusch, MD, FACP is a member of the following medical societies: American College of Physicians and Infectious Diseases Society of America

Disclosure: Nothing to disclose.

Robert G Darling, MD, FACEP  Adjunct Clinical Assistant Professor of Military and Emergency Medicine, Uniformed Services University of the Health Sciences, F Edward Hebert School of Medicine; Associate Director, Center for Disaster and Humanitarian Assistance Medicine

Robert G Darling, MD, FACEP is a member of the following medical societies: American College of Emergency Physicians, American Medical Association, American Telemedicine Association, and Association of Military Surgeons of the US

Disclosure: Nothing to disclose.

Chief Editor

Burke A Cunha, MD  Professor of Medicine, State University of New York School of Medicine at Stony Brook; Chief, Infectious Disease Division, Winthrop-University Hospital

Burke A Cunha, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, and Infectious Diseases Society of America

Disclosure: Nothing to disclose.

References

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  2. Figueiredo LT. Emergent arboviruses in Brazil. Rev Soc Bras Med Trop. Mar-Apr 2007;40(2):224-9. [Medline].

  3. Carrara AS, Coffey LL, Aguilar PV, et al. Venezuelan equine encephalitis virus infection of cotton rats. Emerg Infect Dis. Aug 2007;13(8):1158-65. [Medline]. [Full Text].

  4. Estrada-Franco JG, Navarro-Lopez R, Freier JE, et al. Venezuelan equine encephalitis virus, southern Mexico. Emerg Infect Dis. Dec 2004;10(12):2113-21. [Medline].

  5. Jackson AC, Rossiter JP. Apoptotic cell death is an important cause of neuronal injury in experimental Venezuelan equine encephalitis virus infection of mice. Acta Neuropathol. Apr 1997;93(4):349-53. [Medline].

  6. CDC. Venezuelan equine encephalitis--Colombia, 1995. MMWR Morb Mortal Wkly Rep. Oct 6 1995;44(39):721-4. [Medline].

  7. Morrison AC, Forshey BM, Notyce D, et al. Venezuelan equine encephalitis virus in Iquitos, Peru: urban transmission of a sylvatic strain. PLoS Negl Trop Dis. 2008;2(12):e349. [Medline]. [Full Text].

  8. Fine DL, Roberts BA, Teehee ML, et al. Venezuelan equine encephalitis virus vaccine candidate (V3526) safety, immunogenicity and efficacy in horses. Vaccine. Feb 26 2007;25(10):1868-76. [Medline].

 
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