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A39.81 ICD-10-CM Code: Meningococcal encephalitis

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43, Appendix B.

  • MS-DRG 023 — CRANIOTOMY WITH MAJOR DEVICE IMPLANT OR ACUTE COMPLEX CNS PRINCIPAL DIAGNOSIS WITH MCC OR ANTINEOPLASTIC IMPLANT OR EPILEPSY WITH NEUROSTIMULATOR (MDC 01)
  • MS-DRG 024 — CRANIOTOMY WITH MAJOR DEVICE IMPLANT OR ACUTE COMPLEX CNS PRINCIPAL DIAGNOSIS WITHOUT MCC (MDC 01)
  • MS-DRG 094 — BACTERIAL AND TUBERCULOUS INFECTIONS OF NERVOUS SYSTEM WITH MCC (MDC 01)
  • MS-DRG 095 — BACTERIAL AND TUBERCULOUS INFECTIONS OF NERVOUS SYSTEM WITH CC (MDC 01)
  • MS-DRG 096 — BACTERIAL AND TUBERCULOUS INFECTIONS OF NERVOUS SYSTEM WITHOUT CC/MCC (MDC 01)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Code Overview

Meningococcal encephalitis is a billable ICD-10-CM diagnosis code (A39.81).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Indexed Clinical Terms (4)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

Verify Before Coding

  • MCC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name A39.81 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes1 note: G05 — Encephalitis, myelitis and encephalomyelitis in diseases classified elsewhere.

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: MCC — Major Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 10 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 5 MS-DRGs: DRG 023 (MDC 01), DRG 024 (MDC 01), DRG 094 (MDC 01), DRG 095 (MDC 01), DRG 096 (MDC 01).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):NVS002 — Encephalitis (default); INF003 — Bacterial infections.

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as MCC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

A39.89 — Other meningococcal infections, A39.9 — Meningococcal infection, unspecified, A49.3 — Mycoplasma infection, unspecified site, A49.8 — Other bacterial infections of unspecified site, A49.9 — Bacterial infection, unspecified, B92 — Sequelae of leprosy, B94.2 — Sequelae of viral hepatitis, B94.8 — Sequelae of other specified infectious and parasitic diseases, B94.9 — Sequelae of unspecified infectious and parasitic disease

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical categories (Encephalitis, Bacterial infections).

A17.82 — Tuberculous meningoencephalitis, A32.12 — Listerial meningoencephalitis, A42.82 — Actinomycotic encephalitis, A50.42 — Late congenital syphilitic encephalitis, A52.14 — Late syphilitic encephalitis, A81.1 — Subacute sclerosing panencephalitis, A83.0 — Japanese encephalitis, A83.1 — Western equine encephalitis, A83.2 — Eastern equine encephalitis, A83.3 — St Louis encephalitis, A83.4 — Australian encephalitis, A83.5 — California encephalitis, A83.6 — Rocio virus disease, A83.8 — Other mosquito-borne viral encephalitis, A83.9 — Mosquito-borne viral encephalitis, unspecified, A84.0 — Far Eastern tick-borne encephalitis [Russian spring-summer encephalitis], A84.1 — Central European tick-borne encephalitis, A84.8 — Other tick-borne viral encephalitis, A84.81 — Powassan virus disease, A84.89 — Other tick-borne viral encephalitis, +431 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Encephalitis”, “Meningomyelitis”, “Meningoencephalitis”; these codes share that main term but sit in a different category of the Tabular List.

A17.82 — Tuberculous meningoencephalitis (tuberculous), A28.1 — Cat-scratch disease (due to, cat scratch disease), A32.12 — Listerial meningoencephalitis (in, listeriosis), A42.82 — Actinomycotic encephalitis (in, actinomycosis), A50.42 — Late congenital syphilitic encephalitis (in, syphilis, congenital), A52.14 — Late syphilitic encephalitis (syphilitic), A69.22 — Other neurologic disorders in Lyme disease (in, Lyme disease), A80.9 — Acute poliomyelitis, unspecified (in, poliovirus), A81.1 — Subacute sclerosing panencephalitis (Dawson's), A83.0 — Japanese encephalitis (summer), A83.1 — Western equine encephalitis (Western equine), A83.2 — Eastern equine encephalitis (Eastern equine), A83.3 — St Louis encephalitis (type, C), A83.4 — Australian encephalitis (Australian), A83.5 — California encephalitis (La Crosse), A83.8 — Other mosquito-borne viral encephalitis (Ilheus), A83.9 — Mosquito-borne viral encephalitis, unspecified (equine), A84.0 — Far Eastern tick-borne encephalitis [Russian spring-summer encephalitis] (Far Eastern), A84.1 — Central European tick-borne encephalitis (Czechoslovakian), A84.81 — Powassan virus disease (Powassan), +50 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Gamma-glutamyl Transferase (GGT) Test

Contextual Map

Every relationship of A39.81 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run A39.81 with this related code in Claim Check

Hierarchy

Referenced by Excludes1 notes

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • MDC 01 — Diseases and Disorders of the Nervous System[MDC crossing]: “Diseases and Disorders of the Nervous System — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 8,892 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

  • Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute), meningococcal[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Infection, infected, infective (opportunistic), meningococcal, brain[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Meningoencephalitis, epidemic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Meningomyelitis, meningococcal[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (17)

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder structured relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "A39.81 — Meningococcal encephalitis." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/a39.81-meningococcal-encephalitis

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Meningococcal encephalitis

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027 (effective October 1, 2026), and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to A39.81 in its code family, with their registry titles.

View all codes in the A39 family