B00.4 Herpesviral encephalitis

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

Applicable to

• Herpesviral meningoencephalitis
• Simian B disease

Excludes1 (never code together)

• herpesviral encephalitis due to herpesvirus 6 and 7 (B10.01, B10.09)
• non-simplex herpesviral encephalitis (B10.0-)

Applies from B00 Herpesviral [herpes simplex] infections

Excludes1 (never code together)

• congenital herpesviral infections (P35.2)

Excludes2 (not included here)

• anogenital herpesviral infection (A60.-)
• gammaherpesviral mononucleosis (B27.0-)
• herpangina (B08.5)

MS-DRG index

Defines the logic of DRG(s) 023-024 in MDC 01.

Approximate ICD-9-CM (GEMs)

• 054.3 Herpetic meningoencephalitis (approximate)

Code annotations containing back-references to B00.4

Back-references to B00.4

• Type 1 Excludes: A85 Other viral encephalitis, not elsewhere classified ("encephalitis due to herpesvirus [herpes simplex] (B00.4)")
• Type 2 Excludes: B10.0 Other human herpesvirus encephalitis ("herpes encephalitis NOS (B00.4)")
• Type 2 Excludes: B10.0 Other human herpesvirus encephalitis ("herpes simplex encephalitis (B00.4)")
• Type 2 Excludes: B10.0 Other human herpesvirus encephalitis ("human herpesvirus encephalitis (B00.4)")
• Type 2 Excludes: B10.0 Other human herpesvirus encephalitis ("simian B herpes virus encephalitis (B00.4)")
• Type 1 Excludes: G05 Encephalitis, myelitis and encephalomyelitis in diseases classified elsewhere ("herpesviral [herpes simplex] encephalitis, myelitis and encephalomyelitis (B00.4)")

Back-references to B00

• Type 2 Excludes: B10 Other human herpesviruses ("herpes simplex (B00.-)")
• Type 2 Excludes: B10 Other human herpesviruses ("human herpesvirus NOS (B00.-)")
• Type 2 Excludes: B10 Other human herpesviruses ("human herpesvirus 1 and 2 (B00.-)")
• Code Also: D81.82 Activated Phosphoinositide 3-kinase Delta Syndrome [APDS] ("herpes virus infections (B00.-)")
• Code First: H67 Otitis media in diseases classified elsewhere ("viral disease NEC (B00-B34)")

Diagnosis Index entries for B00.4

• Disease, diseased › simian B
• Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute) › herpesviral
• Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute) › in (due to) › herpes (simplex) virus
• Herpes, herpesvirus, herpetic › encephalitis
• Meningoencephalitis › herpesviral, herpetic
• Meningoencephalitis › in (due to) › herpes

Nearby codes

• B00 Herpesviral [herpes simplex] infections
• B00.0 Eczema herpeticum
• B00.1 Herpesviral vesicular dermatitis
• B00.2 Herpesviral gingivostomatitis and pharyngotonsillitis
• B00.3 Herpesviral meningitis
• B00.4 Herpesviral encephalitis (this code)
• B00.5 Herpesviral ocular disease
• B00.50 Herpesviral ocular disease, unspecified
• B00.51 Herpesviral iridocyclitis
• B00.52 Herpesviral keratitis
• B00.53 Herpesviral conjunctivitis