A81 ICD-10-CA category: Atypical virus infections of central nervous system
A81 isn’t a code on its own. Choose one of the 5 codes beneath it, the one the documentation supports.
Official description
A81Atypical virus infections of central nervous system
ICD-10-CA · Canada
Codes in A81
A81 isn’t a code on its own. Open the code that matches what the note documents.
Notes for A81
As CIHI prints them, with any note A81 takes from the headings above it.
Includes
- Prion diseases of the central nervous system
- Diseases generally recognized as communicable or transmissibleFrom Chapter 1: Certain infectious and parasitic diseases (A00-B99)
Use additional code
Add a code for this detail when the note documents it.
- Use additional code (U82-U84) to identify resistance to antimicrobial drugsFrom Chapter 1: Certain infectious and parasitic diseases (A00-B99)
Excludes
Conditions classified elsewhere.
- Sequelae of:• poliomyelitis (B91)• viral encephalitis (B94.1)From A80-A89 Viral infections of the central nervous system
- Carrier or suspected carrier of infectious disease (Z22.-)certain localized infections - see body system-related chaptersinfectious and parasitic diseases:• complicating pregnancy, childbirth and the puerperium [except obstetrical tetanus] (O98.-)• specific to the perinatal period [except tetanus neonatorum, whooping cough, congenital syphilis, perinatal gonococcal infection and perinatal human immunodeficiency virus [HIV] disease] (P35-P39)influenza and other acute respiratory infections (J00-J22)From Chapter 1: Certain infectious and parasitic diseases (A00-B99)
Where A81 sits
- 1ChapterChapter 1: Certain infectious and parasitic diseases (A00-B99)
- 2Block A80-A89Viral infections of the central nervous system
- 3Category A81Atypical virus infections of central nervous system
Source and release
- Data release
- ICD-10-CA · FY 2026–2027
- Effective date
- Apr 1, 2026
- Publisher
- CIHI
This page is built from the ICD-10-CA catalog that Vero Codes reads when it suggests codes: Canadian Institute for Health Information’s FY 2026–2027 release, imported from the publisher’s file and checked against it. The description, notes and structured data come from the same record.
Frequently asked questions
Is A81 a valid ICD-10-CA code?
No. A81 (Atypical virus infections of central nervous system) is a category heading in CIHI’s ICD-10-CA FY 2026–2027 release. It holds 5 codes; record the one the documentation supports.
Where is A81 in ICD-10-CA?
A81 sits under A80-A89 Viral infections of the central nervous system, within Chapter 1: Certain infectious and parasitic diseases (A00-B99).
What coding notes apply to A81?
ICD-10-CA lists Includes, Excludes, Use additional code notes for A81, including those from the headings it sits under. They are listed on this page with where each one comes from.
Which ICD-10-CA release does this page use?
It uses CIHI’s FY 2026–2027 release, in effect from Apr 1, 2026 to Mar 31, 2027. It is a reference: confirm the code against the current list and the payer’s rules before you submit it.
Codes beside A81
View A80-A89A80Acute poliomyelitisA82RabiesA83Mosquito-borne viral encephalitisA84Tick-borne viral encephalitisA85Other viral encephalitis, not elsewhere classifiedA86Unspecified viral encephalitisA87Viral meningitisA88Other viral infections of central nervous system, not elsewhere classifiedA89Unspecified viral infection of central nervous system