ICD-10 Code A83.4 – Australian encephalitis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code A83.4 – Australian encephalitis
What it is
A83.4 identifies Australian encephalitis, a rare viral encephalitis associated with infection in Australia. Use it when documentation specifically names this diagnosis.
Clinical signs
Clinical features vary; refer to documentation. Encephalitis may present with fever, headache, altered mental status, seizures, or neurologic deficits, but you should code only when the record supports Australian encephalitis.
When to use this code
Use A83.4 when the provider documents Australian encephalitis, including confirmed or suspected cases recorded as the final diagnosis. It may also apply when the chart clearly links encephalitis to this specific viral illness. Check documentation if the cause is not stated.
Do not use for
Do not use this code for encephalitis of another known cause, unspecified viral encephalitis, or encephalopathy without documentation of encephalitis. If the record only says “viral infection” or “neurologic symptoms,” check documentation.
Coding tip
Code A83.4 only when the provider names Australian encephalitis; otherwise, select a more specific or unspecified encephalitis code based on the record.