eMedicine Specialties > Infectious Diseases > CNS Infections

Western Equine Encephalitis: Follow-up

Author: Mohan Nandalur, MD, Staff Physician, Department of Internal Medicine, Section of Cardiovascular Medicine, Washington Hospital Center
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
Contributor Information and Disclosures

Updated: Oct 31, 2007

Follow-up

Further Inpatient Care

  • The patient must be transferred to the ICU when appropriate.
  • Many issues are also secondary to the high mortality rate of the disease.
  • Social work services and other appropriate hospital services should be available to the patients' families.

Further Outpatient Care

  • Because of the potential for high neurologic morbidity, coordinated care and quality follow-up care must be arranged. Patients often require speech therapy, physical therapy, neurodiagnostic follow-up, and potential audiology testing. The primary care physician must also be aware of subtle changes in behavior, intelligence, and motor skills.

Deterrence/Prevention

  • Environmental animal control
    • The potential exists for monitoring the sources of infection by assessing serology of antibodies to western equine encephalitis (WEE) in certain wild birds or sentinel birds.
    • The virus may also be recovered from adult mosquitoes and may provide an opportunity for screening in possible vector habitats. Current screening is ongoing for other arthropod-borne illnesses, such as West Nile encephalitis and EEE.
    • Areas where the disease is endemic, where the virus has been isolated, or areas at high risk should have the vector mosquito population controlled.
    • An early outbreak of WEE should cause potential assessment for and deterrence of an epidemic. This should become easier for environmental screening agencies in the future with newly developed techniques, such as an indirect enzyme immunoassay, which has been developed to screen wild birds for antibodies against WEE.5
  • Global environmental factors: Global factors also play a role in prevention and spread. As noted above, the transmission rate increases during warm seasons, and an increase in global temperature may increase the duration of infectivity in the future.
  • Public information
    • Warn individuals who are at high risk in high-risk areas to take the necessary precautions. This includes appropriate clothing (eg, long pants, long-sleeved shirts), mosquito repellant, and avoidance of areas with high mosquito activity (especially during times of day when mosquitoes are most active).
    • Mosquito netting at nighttime also can be used if appropriate.
    • Having air conditioning in the home has been found to decrease the transmission of the disease. Behavioral patterns such as these have reduced the incidence of disease, even in peak mosquito seasons.6
  • Permethrin 5% cream (marketed for scabies prevention) has been found to deter arthropod bites for up to a week. Treated skin is not an effective repellant, but it often causes the insect to die before biting. A permethrin rinse has also been used on clothing and has been proven effective for prevention.7
  • Surveillance: WEE can be reported electronically to a CDC-run site called ArboNet, which assists states in tracking mosquito-borne viruses.
  • Future prevention: Currently, a vaccine for WEE is available, but it is not in widespread use and may not be effective against certain antigenic variants. The current use for the vaccine is for environmental workers with high exposure risk.

Complications

  • The primary complications other than death are variable levels of CNS impairment. Numerous factors, including location and specific inflammatory cell response, may determine the resulting impairment.
  • Demyelination is a known byproduct of this disease, and it can be detected radiologically. Often, these areas heal quite well, unless overlying fibrosis or cell death occurs.
  • Additional complications include mental retardation, behavioral changes, paralysis, permanent focal neurologic deficits, seizure disorders, cerebellar damage, and choreoathetosis. Cases of Parkinson syndrome have been reported in adults after WEE infection.

Prognosis

  • Patients infected with WEE who do not develop neurologic signs or symptoms have an excellent prognosis.
  • Patients with mild neurologic symptoms often rapidly recover.
  • Once adults recover, they often have very few residual effects.
  • Children who develop neurologic symptoms have a poorer prognosis.
  • In addition, patients who develop seizures are more likely to develop a subsequent lifetime seizure disorder.
  • Reported neurologic sequelae include developmental delay, motor impairments (both pyramidal and extrapyramidal), and residual behavioral problems.

Patient Education

Miscellaneous

Medicolegal Pitfalls

  • As with all critically ill patients, take care to stabilize the patient first. As mentioned above, because of the similarity in presentation between encephalitis and meningitis, implement broad-spectrum antibiotics and an antiviral agent in these patients until more definitive tests are available.
 


More on Western Equine Encephalitis

Overview: Western Equine Encephalitis
Differential Diagnoses & Workup: Western Equine Encephalitis
Treatment & Medication: Western Equine Encephalitis
Follow-up: Western Equine Encephalitis
References
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Further Reading

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Keywords

western equine encephalitis, WEE, inflammation of the brain parenchyma, meninges, herpes simplex virus, arbovirus, Culex tarsalis, C tarsalis, Aedes species, eastern equine encephalitis, EEE, Venezuelan equine encephalitis, VEE, Sindbis virus, neurotropic alphavirus, diffuse CNS involvement, meningitis, meningoencephalitis, St. Louis encephalitis, Aedes albifasciatus, A albifasciatus, encephalitides

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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
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.

Medical Editor

Kenneth C Earhart, MD, FACP, Deputy Head, Disease Surveillance Program, United States Naval Medical Research Unit #3
Kenneth C Earhart, MD, FACP is a member of the following medical societies: American College of Physicians, American Society of Tropical Medicine and Hygiene, Infectious Diseases Society of America, and Undersea and Hyperbaric Medical Society
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

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.

CME Editor

Eleftherios Mylonakis, MD, Clinical and Research Fellow, Department of Internal Medicine, Division of Infectious Diseases, Massachusetts General Hospital
Eleftherios Mylonakis, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Physicians, American Society for Microbiology, 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.

 
 
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