A81.9 – Atypical virus infection of central nervous system, unspecified
ICD-10-CM 2027 diagnosis code · Viral and prion infections of the central nervous system
- Code
A81.9(claims format:A819)- Description
- Atypical virus infection of central nervous system, unspecified
- Short description
- Atypical virus infection of central nervous system, unsp
- Billable
- Yes – valid for HIPAA-covered transactions
- 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
- Parent codes
- A81
Notes for A81.9
- Prion diseases of the central nervous system NOS
Notes inherited from parent codes
Instructional notes at a category or block level apply to every code below it.
A81 – Atypical virus infections of central nervous system
- diseases of the central nervous system caused by prions
- 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-)
Block A80-A89
Index terms for A81.9
Entries in the ICD-10-CM alphabetic index that lead to this code:
- Infection, infected, infective, slow virus
- Infection, infected, infective, atypical, virus
- Disease, diseased, prion, central nervous system
- Infection, infected, infective, virus, viral NOS, slow
- Infection, infected, infective, virus, viral NOS, central nervous system, atypical
- Infection, infected, infective, virus, viral NOS, central nervous system, slow virus
Related codes in A81
Frequently asked questions
What is ICD-10 code A81.9?
A81.9 is the ICD-10-CM code for atypical virus infection of central nervous system, unspecified, in the block A80-A89 (Viral and prion infections of the central nervous system).
Is A81.9 a billable code?
Yes. A81.9 is a billable/specific code that can be used to indicate a diagnosis for reimbursement purposes.
What category does A81.9 belong to?
It belongs to category A81 – Atypical virus infections of central nervous system.
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.