164: West Nile Virus

An estimated 70% to 80% of people infected with West Nile virus (WNV) are asymptomatic. Most symptomatic people experience an acute systemic febrile illness that often includes headache, myalgia, arthralgia, vomiting, diarrhea, or a transient maculopapular rash. Less than 1% of infected people develop neuroinvasive disease, which typically manifests as meningitis, encephalitis, or acute flaccid myelitis. WNV meningitis is indistinguishable clinically from aseptic meningitis caused by other viruses. Patients with WNV encephalitis usually present with fever, headache, seizures, mental status changes, focal neurological deficits, or movement disorders. WNV acute flaccid myelitis is often clinically and pathologically identical to poliovirus-associated poliomyelitis,...