St Louis encephalitis

This code represents an acute viral infection of the central nervous system caused by the St. Louis encephalitis virus, transmitted by mosquitoes. It typically manifests as a febrile illness, headache, nausea, and vomiting, potentially progressing to encephalitis with altered mental status, seizures, and neurological deficits.

Use this code when documentation confirms a diagnosis of St. Louis encephalitis, often based on serological testing (e.g., IgM antibodies in CSF or serum) or viral isolation. This diagnosis is typically made in patients presenting with symptoms consistent with viral encephalitis, especially in endemic regions during mosquito season.

• Differentiate from other arboviral encephalitides; ensure documentation specifically states "St. Louis."
• Code any associated neurological manifestations or sequelae separately, if applicable and documented.
• Confirm the definitive diagnosis; avoid coding based solely on suspected or rule-out diagnoses.