2026 ICD-10-CM Diagnosis Code A39.9Meningococcal infection, unspecified

ICD-10-CM Codes›A00–B99›A30-A49›A39

ICD-10-CM A39.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

A39.9 is a billable ICD-10-CM diagnosis code for meningococcal infection, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 870 through 872. Coders also document this condition as invasive meningococcal disease. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bacterial infections.

Code Identity

ICD-10-CM Code
A39.9
Billable Status
Yes — Valid for Submission
Code Describes
Meningococcal infection, unspecified
Short Description
Meningococcal infection, unspecified
Same as the full description in the CMS dataset.
Parent Code
A39
Meningococcal infection

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA30-A49Other bacterial diseases
CategoryA39Meningococcal infection
This CodeA39.9Meningococcal infection, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Invasive meningococcal disease
  • Meningococcal infectious disease
  • Meningococcal infectious disease caused by Neisseria meningitidis serogroup B
  • Sepsis caused by Meningococcus

Tabular List NotesGuidance

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

Inclusion Terms

  • Meningococcal disease NOS

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.

    • Infection, infected, infective(opportunistic)
      • meningococcal
    • Infection, infected, infective(opportunistic)
      • parameningococcus NOS
    • Meningococcus, meningococcal

Clinical ClassificationClinical

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

CCSR INF003
Bacterial infections
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Meningococcal Disease

Meningococcal disease is the name for any illness that is caused by Neisseria meningitidis bacteria (also called meningococcal bacteria). These illnesses are often severe and can sometimes be deadly. They include infections of the lining of the brain and spinal cord (meningitis) and in the bloodstream (sepsis).

The full article covers:

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

Read the full article at MedlinePlus

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

Convert A39.9 to ICD-9-CMHistory

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

ICD-9-CM
036.9 Meningococcal infect NOS
Exact Match The mapping is direct, with no qualifiers.

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 A39.9Overview

Is A39.9 (Meningococcal infection) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report meningococcal infection, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does A39.9 group to?

When meningococcal infection, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 870, 871, 872, with relative weights from 1.0233 to 6.9118 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of A39.9?

Under the General Equivalence Mappings, meningococcal infection, unspecified converts to ICD-9-CM 036.9 (meningococcal infect NOS). The mapping is a direct match.

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.