Most of those who are infected with West Nile virus do not develop symptoms. The elderly develop symptoms more often than children and young adults.

The most common initial symptoms of West Nile virus is fever.

Initial symptoms of West Nile virus may include:

• Body aches
• Fatigue
• Fever
• Lymph gland swelling
• Headache
• Nausea
• Rash
• Vomiting

Symptoms of a severe West Nile virus infection include:

• Confusion
• Neck pain
• Neck stiffness
• Seizure
• Severe headache
• Sudden weakness in one arm or leg:
• Arm weakness (unilateral)
• Leg weakness (unilateral)