A21.3 ICD-10-CM Code: Gastrointestinal tularemia
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FY 2026 Apr update / Certain infectious and parasitic diseases (A00-B99) / Certain zoonotic bacterial diseases (A20-A28)
A21.3
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceGastrointestinal tularemia
Tularemia is a serious bacterial infection caused by Francisella tularensis, and this code specifically indicates the infection has affected the gastrointestinal system, causing symptoms like abdominal pain, diarrhea, and nausea. This form of tularemia typically results from eating contaminated food or water.
CMS-HCC V28
00
RAF 0
CMS-HCC V24
00
RAF 0
ACA/HHS
00
RAF 0
ESRD/PACE
00
RAF 0
RXHCC
00
RAF 0
Code Trumping
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Code Book Path
Inclusion Terms
Official- Abdominal tularemia
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for A21.3 in this effective period.
Related Child Codes
Includes
Official- deer-fly fever
- infection due to Francisella tularensis
- rabbit fever
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for A21.3 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for A21.3 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for A21.3 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for A21.3 in this effective period.
Buddy Documentation Tip
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is A21.3 an HCC code?
No. A21.3 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
Coder workflow notes
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This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
A21.3 is the ICD-10-CM diagnosis code for gastrointestinal tularemia. Tularemia is a serious bacterial infection caused by Francisella tularensis, and this code specifically indicates the infection has affected the gastrointestinal system, causing symptoms like abdominal pain, diarrhea, and nausea. This form of tularemia typically results from eating contaminated food or water. A21.3 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering certain zoonotic bacterial diseases (a20-a28).
A21.3 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
Verify documentation specifies gastrointestinal involvement rather than other forms of tularemia (typhoidal, ulceroglandular, pneumonic, etc.) before assigning this code.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for A21.3 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify documentation specifies gastrointestinal involvement rather than other forms of tularemia (typhoidal, ulceroglandular, pneumonic, etc.) before assigning this code
- •This is a reportable disease in most jurisdictions; ensure proper reporting requirements are met and consider adding a code for the source of infection if documented