NPI Atlas

A84 – Tick-borne viral encephalitis

ICD-10-CM 2027 diagnosis code · Viral and prion infections of the central nervous system

Non-billable header

ICD-10-CM code A84

Code: A84 (claims format: A84)
Description: Tick-borne viral encephalitis
Billable: No – use a more specific code below
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 1. Certain infectious and parasitic diseases (A00-B99)
Block: A80-A89 Viral and prion infections of the central nervous system

Billable codes under A84

A84 is a header code and cannot be used on claims. Choose the most specific code:

A84.0 – Far Eastern tick-borne encephalitis [Russian spring-summer encephalitis]Billable
A84.1 – Central European tick-borne encephalitisBillable
A84.8 – Other tick-borne viral encephalitisHeader (more codes below)
A84.9 – Tick-borne viral encephalitis, unspecifiedBillable

Notes for A84

Includes:

tick-borne viral meningoencephalitis

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

Block A80-A89

Excludes1 (not coded here):

postpolio syndrome (G14)
sequelae of poliomyelitis (B91)
sequelae of viral encephalitis (B94.1)

Frequently asked questions

What is ICD-10 code A84?

A84 is the ICD-10-CM code for tick-borne viral encephalitis, in the block A80-A89 (Viral and prion infections of the central nervous system).

Is A84 a billable code?

No. A84 is a header code with more specific child codes; report one of the billable codes listed above.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.