Eastern Equine Encephalitis Clinical Presentation

  • Author: Mohan Nandalur, MD; Chief Editor: Burke A Cunha, MD   more...
 
Updated: Jun 9, 2011
 

History

Because of the lack of specific symptoms, eastern equine encephalitis (EEE) is difficult to diagnose. A rewarding diagnostic approach is to determine the extent of the patient’s illness and to determine whether central nervous system (CNS) infection is present. The prodromal phase is often short (average, 5-10 days) and consists of fever, headache, and some abdominal pain with diarrhea. Compared with other alphavirus infections, EEE progresses more rapidly to both CNS involvement and death. Once symptoms arise, the patient often deteriorates rapidly.

Neurologic symptoms include the following:

  • Headache - Most prevalent symptom
  • Nausea or vomiting - Present in both the prodromal and active stages of the infection
  • Confusion
  • Focal neurologic deficits - Sensory or motor loss (relatively low prevalence of focal deficits)
  • Seizures – Reported in roughly 50% of patients (most often generalized tonic-clonic with occasional partial complex seizures)
  • Somnolence
  • Neck stiffness
  • Malaise and weakness
  • Cranial nerve palsies - Often developing either directly from the disease or secondary to elevated CSF pressure (nerves most commonly affected are VI, VII, and occasionally XII)
  • Photophobia
  • Autonomic disturbances (eg, sialorrhea)

Other associated symptoms include the following:

  • Fever - Almost invariably present at some point
  • Chills
  • Abdominal pain
  • Diarrhea
  • Sore throat
  • Arthralgia or myalgia
  • Respiratory difficulty

The following are other important factors to consider in the patient’s history:

  • Social history
  • Recent travel to endemic areas
  • Outdoor exposure history
  • Work related to the care of horses or work located in marshes
  • Recent insect bites
  • Work or home in areas with high mosquito counts
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Physical Examinations

The physical examination for EEE also is nonspecific, yielding findings similar to those seen with many other encephalitides.

Changes in vital signs may include the following:

  • Fever
  • Tachycardia
  • Possible tachypnea

Neurologic findings may include the following:

  • Bilateral papilledema
  • Nuchal rigidity
  • Focal sensory or motor deficit
  • Depressed or hyperactive reflexes
  • Tremors
  • Fasciculations
  • Seizure activity
  • Spastic paralysis

Other findings may include the following:

  • Cyanosis - With respiratory compromise
  • Facial, periorbital, or generalized edema
  • Lymphadenopathy - Not necessarily present

Possible pharyngeal erythema

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Complications

The primary complication, other than death, is often a variable level of CNS impairment. Numerous factors, including location and specific inflammatory cell response, may determine the result.

Demyelination is a known by-product of this disease and can be radiologically detected. Often, these areas heal well, unless overlying fibrosis is present or cell death occurs.

Additional potential complications include the following:

  • Mental retardation
  • Behavioral changes
  • Paralysis
  • Permanent focal neurologic deficits
  • Seizure disorders
  • Emotional lability
  • Adjustment disorders
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Contributor Information and Disclosures
Author

Mohan Nandalur, MD  Staff Physician, Department of Internal Medicine, Section of Cardiovascular Medicine, Washington Hospital Center

Mohan Nandalur, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Cardiology, American College of Physicians-American Society of Internal Medicine, and Phi Beta Kappa

Disclosure: Nothing to disclose.

Coauthor(s)

Andrew W Urban, MD  Chief, Section of Infectious Diseases, Middleton Memorial Veterans Hospital; Clinical Assistant Professor, Department of Internal Medicine, University of Wisconsin at Madison School of Medicine and Public Health

Andrew W Urban, MD is a member of the following medical societies: American College of Physicians-American Society of Internal Medicine

Disclosure: Nothing to disclose.

Specialty Editor Board

Gary L Gorby, MD  Associate Professor, Departments of Internal Medicine and Medical Microbiology and Immunology, Division of Infectious Diseases, Creighton University School of Medicine; Associate Professor of Medicine, University of Nebraska Medical Center; Associate Chair, Omaha Veterans Affairs Medical Center

Gary L Gorby, MD is a member of the following medical societies: Alpha Omega Alpha, American Medical Association, American Society for Microbiology, Infectious Diseases Society of America, and New York Academy of Sciences

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.

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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  5. Sotomayor EA, Josephson SL. Isolation of eastern equine encephalitis virus in A549 and MRC-5 cell cultures. Clin Infect Dis. Jul 1999;29(1):193-5. [Medline].

  6. Davis LE, Beckham JD, Tyler KL. North American encephalitic arboviruses. Neurol Clin. Aug 2008;26(3):727-57, ix. [Medline]. [Full Text].

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  9. Elgart ML. Medical pearl: permethrin can prevent arthropod bites and stings. J Am Acad Dermatol. Aug 2004;51(2):289. [Medline].

 
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