West Nile virus infection with encephalitis

This code signifies a confirmed infection with the West Nile virus that has progressed to involve inflammation of the brain tissue. Patients typically present with neurological symptoms such as altered mental status, seizures, focal neurological deficits, or movement disorders, in addition to systemic viral symptoms.

Apply this code when documentation clearly indicates a diagnosis of West Nile virus infection with associated encephalitis, confirmed by laboratory testing (e.g., positive WNV IgM antibodies in CSF or serum, or WNV RNA detection). This code is appropriate for both initial and subsequent encounters for this specific condition.

• Ensure physician documentation explicitly states "encephalitis" in conjunction with West Nile virus infection.
• Do not use this code if the West Nile virus infection is without neurological manifestations or if it causes other neurological conditions like meningitis or poliomyelitis-like syndrome.
• Confirm laboratory evidence of West Nile virus infection is present in the medical record to support the diagnosis.