ICDwise
A81 ⚠ Non-billable

Atypical virus infections of central nervous system

ICD-10-CM · FY2026 · Certain Infectious and Parasitic Diseases

Code
A81
System
ICD-10-CM
Billable
No — use specific code
Effective
FY2026
Chapter
Certain Infectious and Parasitic Diseases
Source
CMS / CDC NCHS
⚠ Verify before billing. Confirm against the current CMS/NCHS ICD-10-CM files and your payer's rules before claims submission.

Official coding notes

From CMS's ICD-10-CM Tabular List.

Includes
  • diseases of the central nervous system caused by prions
Use additional code
  • 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-)

Frequently asked questions

What is ICD-10 code A81?
ICD-10-CM code A81 represents Atypical virus infections of central nervous system. It is a non-billable header code requiring a more specific subcategory in the Certain Infectious and Parasitic Diseases chapter, effective October 1, 2025 – September 30, 2026.
Is A81 billable?
No. A81 is a non-billable header. Select a more specific subcategory for claims submission.
What chapter is A81 in?
A81 belongs to the Certain Infectious and Parasitic Diseases chapter (A00–B99) of ICD-10-CM.

Related codes in the A81 category

A81.0 Creutzfeldt-Jakob disease Non-billable A81.1 Subacute sclerosing panencephalitis Billable A81.2 Progressive multifocal leukoencephalopathy Billable A81.8 Other atypical virus infections of central nervous system Non-billable A81.9 Atypical virus infection of central nervous system, unspecified Billable A81.00 Creutzfeldt-Jakob disease, unspecified Billable A81.01 Variant Creutzfeldt-Jakob disease Billable A81.09 Other Creutzfeldt-Jakob disease Billable

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