A85.1 Adenoviral encephalitis

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.

Applicable to

• Adenoviral meningoencephalitis

Applies from A85 Other viral encephalitis, not elsewhere classified

Includes

• specified viral encephalomyelitis NEC
• specified viral meningoencephalitis NEC

Excludes1 (never code together)

• 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)

MS-DRG index

Defines the logic of DRG(s) 097-099 in MDC 01.

Approximate ICD-9-CM (GEMs)

• 049.8 Other specified non-arthropod-borne viral diseases of central nervous system (approximate)

Code annotations containing back-references to A85.1

Back-references to A85.1

• Type 1 Excludes: G05 Encephalitis, myelitis and encephalomyelitis in diseases classified elsewhere ("adenoviral encephalitis, myelitis and encephalomyelitis (A85.1)")

Diagnosis Index entries for A85.1

• Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute) › in (due to) › adenovirus

Nearby codes

• A85 Other viral encephalitis, not elsewhere classified
• A85.0 Enteroviral encephalitis
• A85.1 Adenoviral encephalitis (this code)
• A85.2 Arthropod-borne viral encephalitis, unspecified
• A85.8 Other specified viral encephalitis