2026 ICD-10-CM Diagnosis Code G05.3Encephalitis and encephalomyelitis in diseases classified elsewhere

ICD-10-CM Codes›G00–G99›G00-G09›G05

ICD-10-CM G05.3
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

G05.3 is a billable ICD-10-CM diagnosis code for encephalitis and encephalomyelitis in diseases classified elsewhere. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). The code is a manifestation code that cannot be reported as the principal diagnosis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Encephalitis.

Code Identity

ICD-10-CM Code
G05.3
Billable Status
Yes — Valid for Submission
Code Describes
Encephalitis and encephalomyelitis in diseases classified elsewhere
Short Description
Encephalitis and encephalomyelitis in diseases classd elswhr
Parent Code
G05
Encephalitis, myelitis and encephalomyelitis in diseases classified elsewhere

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG00-G09Inflammatory diseases of the central nervous system
CategoryG05Encephalitis, myelitis and encephalomyelitis in diseases classified elsewhere
This CodeG05.3Encephalitis and encephalomyelitis in diseases classified elsewhere

Code EditsBilling

Medicare Code Editor checks that affect claim validity for G05.3.

Manifestation diagnoses
Manifestation codes describe the manifestation of an underlying disease, not the disease itself, and therefore should not be used as a principal diagnosis.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • African trypanosomiasis
  • Amebic encephalitis
  • Amebic infection of central nervous system
  • Arenavirus encephalitis
  • Bacterial encephalitis
  • Bacterial infectious disease of brain
  • Borrelia infection of central nervous system
  • Brainstem encephalitis
  • Coenurosis
  • Cysticercosis of brain
  • Cysticercosis of central nervous system
  • Dementia due to paraneoplastic encephalitis
  • Disease caused by Hantavirus
  • Disorder of spinal cord co-occurrent with human immunodeficiency virus infection
  • Echinococcus granulosus infection
  • Encephalitic tic disorder
  • Encephalitis caused by Borrelia
  • Encephalitis caused by Coenurus cerebralis
  • Encephalitis caused by Echinococcus granulosus
  • Encephalitis caused by human immunodeficiency virus type 1
  • Encephalitis caused by Leptospira
  • Encephalitis caused by Nocardia
  • Encephalitis caused by protozoa
  • Encephalitis caused by Schistosoma
  • Encephalitis caused by Schistosoma haematobium
  • Encephalitis caused by Schistosoma japonicum
  • Encephalitis caused by Schistosoma mansoni
  • Encephalitis caused by Taenia solium
  • Encephalitis caused by Trypanosoma brucei
  • Encephalitis caused by Trypanosoma brucei gambiense
  • Encephalitis caused by Trypanosoma brucei rhodesiense
  • Encephalitis with AIDS
  • Encephalomyelitis caused by bacterium
  • Encephalomyelitis caused by Coxiella burnetii
  • Encephalomyelitis caused by Neisseria meningitidis
  • Encephalomyelitis with AIDS
  • Encephalopathy with AIDS
  • Fungal encephalitis
  • Fungal infection of brain
  • Fungal infection of cerebrum
  • Fungal ventriculitis
  • Human immunodeficiency virus encephalitis
  • Human immunodeficiency virus I infection
  • Infection by Coenurosis cerebralis
  • Infection by Multiceps multiceps
  • Infection by Trypanosoma gambiense
  • Infection caused by Junin virus
  • Infection caused by Lassa virus
  • Infection caused by Machupo virus
  • Infection caused by Tropheryma
  • Infection causing encephalomyelitis
  • Infection of brain caused by Form Dematiaceae
  • Infection of central nervous system caused by Echinococcus
  • Infective ventriculitis
  • Junin virus encephalitis
  • Lassa virus encephalitis
  • Limbic encephalitis
  • Machupo virus encephalitis
  • Malabsorption caused by infective agent
  • Meningococcal encephalitis
  • Mycobacterial encephalomyelitis
  • Myelitis caused by bacterium
  • Myelitis co-occurrent with human immunodeficiency virus infection
  • Myelitis with AIDS
  • Myelopathy with AIDS
  • Neuro - Whipple's disease
  • Paraneoplastic encephalitis
  • Paraneoplastic encephalomyelitis
  • Paraneoplastic isolated brainstem encephalitis
  • Paraneoplastic limbic encephalitis
  • Phaeohyphomycosis
  • Primary amebic encephalitis
  • Primary encephalitis
  • Retroviridae encephalitis
  • Schistosoma encephalomyelitis
  • Schistosoma haematobium infection
  • Schistosoma japonicum infection
  • Schistosoma mansoni infection
  • Sin Nombre virus encephalitis
  • Trypanosomiasis with encephalitis
  • Ventriculitis of the brain
  • Whipple's disease

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Meningoencephalitis in diseases classified elsewhere

Code First

  • underlying disease

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Encephalomyelitis
      • in diseases classified elsewhere
    • Meningoencephalitis
      • in (due to)
        • diseases classified elsewhere

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NVS002
Encephalitis
Default principal diagnosis: inpatient No · outpatient No

Clinical InformationClinical

  • Limbic Encephalitis

    a paraneoplastic syndrome marked by degeneration of neurons in the limbic system. clinical features include hallucinations, loss of episodic memory; anosmia; ageusia; temporal lobe epilepsy; dementia; and affective disturbance (depression). circulating anti-neuronal antibodies (e.g., anti-hu; anti-yo; anti-ri; and anti-ma2) and small cell lung carcinomas or testicular carcinoma are frequently associated with this syndrome.

  • Cerebral Phaeohyphomycosis

    cns infections caused by neurotropic dematiaceous fungi that contain melanin in their cell walls. the infections often result in brain abscess; encephalitis; and meningitis in patients who are often immunocompetent. the common causative fungi include members cladophialophora bantiana, exophiala dermatitidis, rhinocladiella mackenziei, and ochroconis gallopavum. r. mackenziei infection is seen almost exclusively in patients from the middle east.

  • Phaeohyphomycosis

    opportunistic infections caused by the dematiaceous (darkly pigmented) mitosporic fungi of alternaria, bipolaris, cladosporium, curvularia, and exophiala. these fungi have pigmented hyphae due to melanin in the cell wall. the initial subcutaneous cyst from the infection can become systemic and spread rapidly to renal, pulmonary and cerebral systems (see cerebral phaeohyphomycosis) in an immunocompromised host.

  • Limbic Encephalitis

    a rare disorder characterized by degenerative changes in the limbic area of the brain. causes include infections and autoimmune conditions; it may also manifest as a paraneoplastic syndrome, most often caused by small cell lung carcinoma. signs and symptoms include behavioral changes, hallucinations and dementia.

  • Schistosoma Japonicum Infection

    an infection that is caused by schistosoma japonicum.

  • Schistosoma Mansoni Infection

    an infection that is caused by schistosoma mansoni.

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.

Convert G05.3 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
323.41 Ot encph/mye ot inf else
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About G05.3Overview

Is G05.3 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report encephalitis and encephalomyelitis in diseases classified elsewhere on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Can G05.3 be a principal diagnosis?

No. This is a manifestation code: encephalitis and encephalomyelitis in diseases classified elsewhere describes the manifestation of an underlying disease rather than the disease itself, so the underlying condition is sequenced first.

What is the ICD-9 equivalent of G05.3?

Under the General Equivalence Mappings, encephalitis and encephalomyelitis in diseases classified elsewhere converts to ICD-9-CM 323.41 (ot encph/mye ot inf else). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.