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ICD-10-CM category A81: Atypical virus infections of central nervous system

Category A81 is a heading in chapter 1 (Certain infectious and parasitic diseases (A00-B99)), section Viral and prion infections of the central nervous system (A80-A89). It is not billable; report one of the 10 complete codes below.

Notes that apply to every A81 code

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-)

Billable codes in A81

Billable FY2027 ICD-10-CM codes in category A81
CodeDescription
A81.00Creutzfeldt-Jakob disease, unspecified
A81.01Variant Creutzfeldt-Jakob disease
A81.09Other Creutzfeldt-Jakob disease
A81.1Subacute sclerosing panencephalitis
A81.2Progressive multifocal leukoencephalopathy
A81.81Kuru
A81.82Gerstmann-Straussler-Scheinker syndrome
A81.83Fatal familial insomnia
A81.89Other atypical virus infections of central nervous system
A81.9Atypical virus infection of central nervous system, unspecified

Sources

Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-10. Verify against the primary file before billing or contracting decisions. The reference methodology explains how each figure is computed from these files.

Codes from the FY2027 ICD-10-CM files (all chapters). Report the code that matches the documentation and the Official Guidelines; this list is not coding advice.