2027 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 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

A21.3 is a billable ICD-10-CM diagnosis code for gastrointestinal tularemia. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 371 through 373. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 1 closely related codes. 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

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to A21.3: its own notes plus those printed at A21 and Chapter 1. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From A21 Tularemia applies to 7 codes
  • deer-fly fever
  • infection due to Francisella tularensis
  • rabbit fever
From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • diseases generally recognized as communicable or transmissible

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Abdominal tularemia

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • carrier or suspected carrier of infectious disease (Z22.-)
  • certain localized infections - see body system-related chapters
  • infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
  • infectious and parasitic diseases specific to the perinatal period (P35-P39)
  • influenza and other acute respiratory infections (J00-J22)

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • code to identify resistance to antimicrobial drugs (Z16.-)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

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.

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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About A21.3Overview

What is the ICD-10 code for gastrointestinal tularemia?

The ICD-10-CM code for gastrointestinal tularemia is A21.3 (sometimes written as A213). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

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, 2026 through September 30, 2027.

What MS-DRG does A21.3 group to?

When gastrointestinal tularemia is the principal diagnosis on an inpatient stay, it groups to MS-DRG 372, 371, 373, with relative weights from 0.6945 to 1.7087 depending on complications. Higher weights mean higher Medicare reimbursement.

Is A21.3 a CC or MCC?

CMS lists A21.3 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 1 closely related codes in its exclusion list.

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.