2027 ICD-10-CM Diagnosis Code A85Other viral encephalitis, not elsewhere classified

ICD-10-CM Codes›A00–B99›A80-A89›A85

ICD-10-CM A85
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

A85 is a non-billable ICD-10-CM category code for other viral encephalitis, not elsewhere classified, so it cannot be submitted on claims. Use a more specific code from this category instead, such as A85.0, A85.1, A85.2, and A85.8.

Code Identity

ICD-10-CM Code
A85
Billable Status
No — Non-Billable Category
Code Describes
Other viral encephalitis, not elsewhere classified
Short Description
Other viral encephalitis, not elsewhere classified
Same as the full description in the CMS dataset.
Chapter
A80-A89
Viral and prion infections of the central nervous system

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA80-A89Viral and prion infections of the central nervous system
CategoryA85Other viral encephalitis, not elsewhere classified
This CodeA85Other viral encephalitis, not elsewhere classified

Specific Coding for Other viral encephalitis, not elsewhere classifiedOverview

Non-specific codes like A85 require more characters. Use one of these billable codes instead:

  • Use A85.0 for Enteroviral encephalitis

  • Use A85.1 for Adenoviral encephalitis

  • Use A85.2 for Arthropod-borne viral encephalitis, unspecified

  • Use A85.8 for Other specified viral encephalitis

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to A85: its own notes plus those printed at block A80-A89 and Chapter 1. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

On A85 itself
  • specified viral encephalomyelitis NEC
  • specified viral meningoencephalitis NEC
From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • diseases generally recognized as communicable or transmissible

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

On A85 itself
  • encephalitis due to cytomegalovirus (B25.8)
  • encephalitis due to herpesvirus NEC (B10.0-)
  • encephalitis due to herpesvirus [herpes simplex] (B00.4)
  • encephalitis due to measles virus (B05.0)
  • encephalitis due to mumps virus (B26.2)
  • encephalitis due to poliomyelitis virus (A80.-)
  • encephalitis due to zoster (B02.0)
  • lymphocytic choriomeningitis (A87.2)
  • myalgic encephalomyelitis (G93.32)
From Block A80-A89 Viral and prion infections of the central nervous system applies to 48 codes
  • postpolio syndrome (G14)
  • sequelae of poliomyelitis (B91)
  • sequelae of viral encephalitis (B94.1)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • 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)

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • code to identify resistance to antimicrobial drugs (Z16.-)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Patient EducationClinical

Encephalitis

Encephalitis is inflammation (swelling) of the brain. It can happen when an infection or medical condition that affects the brain activates your immune system. The inflammation can cause a wide range of symptoms. In extreme cases, it can lead to brain damage, stroke, or even death.

The full article covers:

  • What is encephalitis?
  • What causes encephalitis?
  • Who is more likely to get encephalitis?
  • What are the symptoms of encephalitis?
  • How is encephalitis diagnosed?
  • What are the treatments for encephalitis?
  • Can encephalitis be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About A85Overview

What is the ICD-10 code for other viral encephalitis, not elsewhere classified?

A85 is the ICD-10-CM category for other viral encephalitis, not elsewhere classified, but it is a non-billable header: claims need a more specific code from this category, listed on this page.

Is A85 (Other viral encephalitis, not elsewhere classified) a billable code?

No. This is a category header that groups the codes for other viral encephalitis, not elsewhere classified, and headers cannot be submitted on claims. Claims for other viral encephalitis, not elsewhere classified need a more specific code from this category, such as A85.0, A85.1, and A85.2.

Can A85 be reported with B25.8?

Not as a rule. The Excludes1 note on A85 lists "encephalitis due to cytomegalovirus (B25.8)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).