A81 — Atypical virus infections of central nervous system
Is A81 billable?
No — A81 is a non-billable header code. A81 groups more specific codes and cannot be submitted on a claim. A valid ICD-10-CM code must be reported at the highest level of specificity available in its branch. Select one of the 10 billable codes beneath A81.
Billable codes under this header
- A81.1Subacute sclerosing panencephalitis
- A81.2Progressive multifocal leukoencephalopathy
- A81.9Atypical virus infection of central nervous system, unspecified
- A81.00Creutzfeldt-Jakob disease, unspecified
- A81.01Variant Creutzfeldt-Jakob disease
- A81.09Other Creutzfeldt-Jakob disease
- A81.81Kuru
- A81.82Gerstmann-Straussler-Scheinker syndrome
- A81.83Fatal familial insomnia
- A81.89Other atypical virus infections of central nervous system
A81 at a glance
| Code | A81 |
|---|---|
| Description | Atypical virus infections of central nervous system |
| Billable | No — header code |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
Use additional code
Report an additional code alongside A81 to fully describe the condition. A81 is sequenced first.
- code, if applicable, to identify:
- dementia with anxiety (F02.84, F02.A4, F02.B4, F02.C4)
- dementia with behavioral disturbance (F02.81-, F02.A1-, F02.B1-, F02.C1-)
- dementia with mood disturbance (F02.83, F02.A3, F02.B3, F02.C3)
- dementia with psychotic disturbance (F02.82, F02.A2, F02.B2, F02.C2)
- dementia without behavioral disturbance (F02.80, F02.A0, F02.B0, F02.C0)
- mild neurocognitive disorder due to known physiological condition (F06.7-)
Includes
Conditions classified to A81.
- diseases of the central nervous system caused by prions
Excludes1 — never code together — inherited from A80-A89
The conditions below can never be reported together with A81 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
Use additional code — inherited from Chapter 1
Report an additional code alongside A81 to fully describe the condition. A81 is sequenced first.
- code to identify resistance to antimicrobial drugs (Z16.-)
Excludes2 — not included here — inherited from Chapter 1
The conditions below are not part of A81, but a patient may have both at the same time. When documentation supports it, A81 and the excluded code may both be reported.
- carrier or suspected carrier of infectious disease (Z22.-)
- certain localized infections - see body system-related chapters
- infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
- infectious and parasitic diseases specific to the perinatal period (P35-P39)
- influenza and other acute respiratory infections (J00-J22)
What codes fall under A81? (5)
How long has A81 existed?
A81 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.