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Eastern equine encephalitis

Eastern equine encephalitis is a rare but often severe mosquito-borne alphavirus infection that can progress from a nonspecific febrile illness to fulminant encephalitis with high morbidity and mortality

Prevalence

< 1 / 100 000

5 - 10

US Estimated

0 - 1

Europe Estimated

Age of Onset

All ages

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ICD-10

A83.2

Inheritance Pattern

Autosomal dominant

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Autosomal recessive

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Mitochondrial/Multigenic

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X-linked dominant

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X-linked recessive

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5 Facts you should know

FACT

1

EEE is a mosquito-borne alphavirus causing severe encephalitis with high mortality and neurologic sequelae

FACT

2

Seasonal outbreaks occur in endemic regions; birds/horses are amplifying hosts and humans are dead-end hosts

FACT

3

Diagnosis relies on IgM serology and PCR in CSF/serum; imaging may show thalamic/basal ganglia involvement

FACT

4

There is no specific antiviral therapy; management is supportive with seizure control and ICP management

FACT

5

Prevention focuses on vector control, repellents, protective clothing, and community abatement programs

Eastern equine encephalitis is also known as...

Eastern equine encephalitis is also known as:

  • EEE
  • EEEV infection
  • Eastern equine encephalitis virus disease

What’s your Rare IQ?

What is the primary vector for Eastern equine encephalitis virus?

Common signs & symptoms

Systemic phase

  • Fever, chills, malaise, myalgias, headache, vomiting

Neuroinvasive disease

  • Altered mental status, seizures, focal neurologic deficits

Meningoencephalitis signs

  • Nuchal rigidity, photophobia, decreased consciousness

CSF

  • Lymphocytic pleocytosis often; imaging may show encephalitic changes

Rapid progression possible; high ICU need in severe cases

Current treatments

No antiviral shown effective; treatment is supportive care (often ICU-level)

Airway/ventilation support as needed; seizure management; ICP monitoring/management in severe encephalitis

Public health prevention

  • Mosquito avoidance, vector control; exposure counseling

References:

  1. Banda C, et al. Eastern Equine Encephalitis. StatPearls. 2023.