Clinical presentation

presentation

Japanese Encephalitis (JE) is primarily a disease of children (although all age groups can be affected)

• most adults in endemic countries have natural immunity after childhood infection (1)

The incubation period is from 5 to 15 days:

• in survivors, the illness may range from asymptomatic infection to severe encephalitis with a high mortality and a high rate of permanent neurological sequelae (2)
  • most infections are asymptomatic (about one in 250 infections is estimated to become clinically apparent)
  • acute encephalitis is the most commonly recognized clinical manifestation of the disease (4)
  • in symptomatic cases the severity of the disease varies
    • mild disease is characterized by febrile headache or aseptic meningitis
    • illness usually begins with rapid onset and progression of fever, headache, and vomiting
    • over the next few days mental status of the patient changes and may develop focal neurologic deficits, generalized weakness, and movement disorders
    • Parkinson's-like syndrome with mask-like facies, tremor, cogwheel rigidity, and choreoathetoid movements are often seen
    • acute flaccid paralysis, with clinical and pathological features similar to those of poliomyelitis, has also been associated with JEV infection
    • seizures are common, especially among children.

Reference:

• (1) Campbell GL et al. Estimated global incidence of Japanese encephalitis: a systematic review. Bull World Health Organ. 2011;89(10):766-74
• (2) Immunisation Against Infectious Disease - "The Green Book". Chapter 20 Japanese encephalitis (January 2013)
• (3) World Health Organization (WHO). International Travel and Health. Chapter 5 Infectious diseases of potential risk for travelers
• (4) Centers for Disease Control and Prevention (CDC) 2011. Chapter 3 Infectious Diseases Related To Travel