2026 ICD-10-CM Diagnosis Code A21.3Gastrointestinal tularemia

ICD-10-CM Codes›A00–B99›A20-A28›A21

ICD-10-CM A21.3
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

A21.3 is a billable ICD-10-CM diagnosis code for gastrointestinal tularemia. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 371 through 373. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bacterial infections and Intestinal infection.

Code Identity

ICD-10-CM Code
A21.3
Billable Status
Yes — Valid for Submission
Code Describes
Gastrointestinal tularemia
Short Description
Gastrointestinal tularemia
Same as the full description in the CMS dataset.
Parent Code
A21
Tularemia

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA20-A28Certain zoonotic bacterial diseases
CategoryA21Tularemia
This CodeA21.3Gastrointestinal tularemia

Tabular List NotesGuidance

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

Inclusion Terms

  • Abdominal tularemia

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.

    • Ingestion
      • tularemia
    • Tularemia
      • abdominal
    • Tularemia
      • cryptogenic
    • Tularemia
      • enteric
    • Tularemia
      • gastrointestinal
    • Tularemia
      • ingestion
    • Tularemia
      • intestinal

Clinical ClassificationClinical

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

CCSR INF003
Bacterial infections
Default principal diagnosis: inpatient No · outpatient No
CCSR DIG001
Intestinal infection
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Tularemia

    a plague-like disease of rodents, transmissible to man. it is caused by francisella tularensis and is characterized by fever, chills, headache, backache, and weakness.

  • Francisella tularensis

    the etiologic agent of tularemia in man and other warm-blooded animals.

  • Tularemia

    a serious gram-negative bacterial infection caused by francisella tularensis. it is transmitted to humans through bites from infected insects, inhaling airborne bacteria, handling infected animals, or consuming contaminated food or water. signs and symptoms include skin ulcers, mouth sores, lymphadenopathy, sore throat, fever and pneumonia.

Patient EducationClinical

Bacterial Infections

Bacteria are tiny organisms (living things) that have only one cell. Under a microscope, they look like balls, rods, or spirals. They can be found almost everywhere on Earth. There are lots of bacteria in and on your body. In fact, your body has about 10 times more bacteria cells than human cells.

The full article covers:

  • What are bacteria?
  • How do bacterial infections spread?
  • What are the treatments for bacterial infections?
  • Can bacterial infections be prevented?

Read the full article at MedlinePlus

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

Convert A21.3 to ICD-9-CMHistory

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

ICD-9-CM
021.1 Enteric tularemia
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 A21.3Overview

Is A21.3 (Tularemia) a billable code?

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

What MS-DRG does A21.3 group to?

When gastrointestinal tularemia is the principal diagnosis on an inpatient stay, it groups to MS-DRG 371, 372, 373, with relative weights from 0.7274 to 1.7731 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of A21.3?

Under the General Equivalence Mappings, gastrointestinal tularemia converts to ICD-9-CM 021.1 (enteric tularemia). 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.