ICD-10 Code A84.1 – Central European tick-borne encephalitis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code A84.1 – Central European tick-borne encephalitis
What it is
A84.1 identifies Central European tick-borne encephalitis, a viral infection of the central nervous system spread by infected ticks. Use it when documentation specifies this encephalitis form rather than another tick-borne illness.
Clinical signs
Clinical features vary; refer to documentation. Standard references describe fever, headache, neurologic symptoms, and signs of meningitis or encephalitis, sometimes after an initial flu-like illness.
When to use this code
Use A84.1 when the provider documents Central European tick-borne encephalitis, tick-borne encephalitis, or a confirmed equivalent diagnosis. Apply it for inpatient or outpatient encounters where the condition is the reason for care or an active diagnosis. Check documentation if the record only states viral encephalitis without a specific cause.
Do not use for
Do not use this code for other viral encephalitides, meningitis without encephalitis, or nonspecific tick exposure. If the chart does not clearly identify Central European tick-borne encephalitis, check documentation.
Coding tip
Code the documented encephalitis type exactly; if the organism or regional subtype is unclear, query before assigning A84.1.