Japanese encephalitis virus infections cause a mild illness within 2 weeks after the mosquito bite.

The most common symptoms of Japanese encephalitis include:

• Body aches
• Fatigue
• Fever
• Headache:
• May be mild to moderate
• Nausea
• Rash
• Sensitivity to bright light
• Vomiting

Rarely, the infection worsens, causing severe symptoms.

Symptoms of severe Japanese encephalitis include:

• Severe headache
• Neck pain
• Neck stiffness
• Arm weakness (unilateral)
• Leg weakness (unilateral)
• Arm and leg weakness (unilateral)
• Confusion
• Lethargy:
• Excessive sleepiness or drowsiness
• Seizure