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Eastern Equine Encephalitis

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Eastern Equine Encephalitis, Eastern Equine Encephalomyelitis, Triple E

  • See Also
  1. Encephalitis
  • Epidemiology
  1. Incidence human cases in U.S.: 6 cases per year (rare)
    1. However, increased outbreak seen in 2024 on U.S. East Coast
  • Background
  1. First described in an epidemic Encephalitis affecting horses in 1931, Massachusetts
  • Pathophysiology
  1. Arbovirus (Togavirus) primarily causing Encephalitis in horses (as well as donkeys, zebras)
    1. Similar Arboviruses include Western Equine Encephalitis and Venezuelan Encephalitis
    2. Mosquito-bird cycle maintain virus between mammalian infections
    3. Mammals (horses, humans) do not transmit the virus back to Mosquitos
  2. Found in eastern north america (esp. coastal plains of the eastern U.S. and gulf coast)
    1. Most common in Florida, Georgia, Maryland, Wisconsin, and New Jersey
    2. Seasonal: May to October
  3. Transmitted to humans via aedes Mosquito Bite (zoonotic infection)
    1. Incubation 4 to 10 days
  • Findings
  1. See Encephalitis
  2. Initial
    1. Fever
    2. Headache
    3. Photophobia
    4. Myalgias
    5. Nuchal Rigidity
  3. Later
    1. Altered Mental Status to coma
    2. Seizures
  • Diagnostics
  1. See Encephalitis
  • Management
  1. See Encephalitis
  2. Supportive care (including airway protection)
  3. Additional measures
    1. Corticosteroids
    2. Intravenous Immunoglobulin (IVIg) has been used in Western Equine Encephalitis
    3. Anticonvulsants
  • Prognosis
  1. Mortality >33 to 50%
  2. High risk fo residual neurologic deficits (including paralysis) and Epilepsy in survivors
  • Prevention
  1. See Prevention of Vector-borne Infection
  2. Eastern Equine Encephalitis Vaccine is only available for horses (not for use in humans)
  3. Insect Repellent
  4. Long sleeve shirts and pants
  5. Avoid outdoors at dusk and evening hours
  6. Avoid areas of standing water
  • Resources
  1. Eastern Equine Encephalitis (CDC)
    1. https://www.cdc.gov/eastern-equine-encephalitis/site.html
  2. Eastern Equine Encephalitis (Stat Pearls)
    1. https://www.ncbi.nlm.nih.gov/books/NBK557692/
  • References
  1. Herbert and Talan (2024) EM: Rap, 9/16/2024