Last reviewed: November 2017
Last updated: December  2016

Summary

Definition

History and exam

Key diagnostic factors

  • presence of risk factors
  • fever (≥37.5°C)
  • headache
  • seizures

Other diagnostic factors

  • nausea/vomiting
  • myalgias/arthralgias
  • neck stiffness (nuchal rigidity)
  • focal weakness (decreased motor function)
  • photophobia
  • abdominal pain
  • altered mental status
  • cranial nerve palsy
  • tremors
  • drowsiness
  • meningismus
  • diarrhoea
  • cerebral oedema
  • intracranial hypertension
  • aseptic meningitis
  • haemophagocytic lymphohistiocytosis
  • hemiparesis

Risk factors

  • travel/residence in endemic areas (e.g., swamp/wetlands along the east coast of North America, or rural/tropical areas of Central and South America)
  • working in endemic areas (e.g., swamp/wetlands along the east coast of North America, or rural/tropical areas of Central and South America)
  • outdoor recreational activities in endemic areas (e.g., swamps/wooded wetlands along the east coast of North America, or rural/tropical areas of Central and South America)
  • seasonal factors favouring breeding of mosquitoes
  • age <15 years or >50 years
  • occupational exposure (laboratory)
  • short length of prodrome (<3 days)
  • bioterrorism

Diagnostic investigations

1st investigations to order

  • enzyme-linked immunosorbent assay (ELISA)
  • MRI
  • plaque reduction neutralisation test (PRNT)
  • FBC
  • basic metabolic panel
Full details

Investigations to consider

  • CSF cell count, chemistries (e.g., glucose, protein), and viral detection
  • CT
  • EEG
Full details

Treatment algorithm

Contributors

Authors VIEW ALL

Assistant Professor

Division of Infectious Disease and Global Medicine

University of Florida

Gainesville

FL

Disclosures

AV is the author of a reference cited in this monograph.

Peer reviewers VIEW ALL

Infectious Diseases Consultant

Naples Community Hospital

Naples

FL

Disclosures

MGM declares that he has no competing interests.

Research Physician

US Naval Medical Research Unit 6 (NAMRU-6)

Iquitos

Peru

Disclosures

SV declares that he has no competing interests.

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