What is ICD-10 code A03.1?

A03.1 is the ICD-10-CM diagnosis code for Shigellosis due to Shigella flexneri. It belongs to the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99). A03.1 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. A03.1 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. A03.1 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. A03.1 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does A03.1 map to under V28?

A03.1 has no payable CMS-HCC V28 mapping in the final FY2026 CMS file.

What RAF reference is published for A03.1?

A03.1 has no V28 reference coefficient because the final FY2026 source verifies no payable V28 mapping.

What is the V28 vs V24 difference for A03.1?

A03.1 has verified no payable V28 mapping in the final FY2026 source. Select a historical effective period before making any V24 comparison.

2026 ICD-10-CM A03.1: Shigellosis due to Shigella flexneri

A03.1 is not a CMS-HCC payment code. MEAT criteria · RAF Calculator · HCC coding software

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Code lookupA03.1

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Certain infectious and parasitic diseases (A00-B99) / Intestinal infectious diseases (A00-A09)

A03.1

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Shigellosis due to Shigella flexneri

A bacterial infection of the intestines caused by Shigella flexneri bacteria, which spreads through contaminated food or water and causes severe diarrhea, abdominal cramps, and fever. This is a contagious disease that primarily affects the digestive system.

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

N/A

—

Not risk-adjusted for this model/period.

Not mapped

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

N/A

—

Not risk-adjusted for this model/period.

Not mapped

ESRD/PACE

N/A

—

Not risk-adjusted for this model/period.

Not mapped

RXHCC

N/A

—

Not risk-adjusted for this model/period.

Not mapped

Code Book Path

Official

A03Shigellosis A03.1Shigellosis due to Shigella flexneri

Inclusion Terms

Official

Group B shigellosis

Excludes 2

Official

carrier or suspected carrier of infectious disease (Z22.-)Inherited from A00-B99
infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)Inherited from A00-B99
infectious and parasitic diseases specific to the perinatal period (P35-P39)Inherited from A00-B99
influenza and other acute respiratory infections (J00-J22)Inherited from A00-B99

Related Codes

Official

A03.0Shigellosis due to Shigella dysenteriae A03.2Shigellosis due to Shigella boydii A03.3Shigellosis due to Shigella sonnei A03.8Other shigellosis A03.9Shigellosis, unspecified

Includes

Official

diseases generally recognized as communicable or transmissibleInherited from A00-B99

Excludes 1

Official

certain localized infections - see body system-related chaptersInherited from A00-B99

Code First

Official

No Code First sequencing instructions are included in this display for A03.1. Check the code and parent instructions in the Code Book.

Use Additional

Official

code to identify resistance to antimicrobial drugs (Z16.-)Inherited from A00-B99

Code Also

Official

No Code Also instructions are included in this display for A03.1. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Verify the specific Shigella species (flexneri) is documented in the medical record before assigning this code, as different species have different codes (A03.0, A03.1, A03.2, A03.3, A03.9)

Document any complications such as dehydration, electrolyte imbalances, or systemic manifestations separately, as these may require additional codes

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is A03.1 an HCC code?

No. A03.1 is a billable ICD-10-CM code with no mapping under the CMS-HCC V28 or V24 community payment models, and none under the ESRD, Part D RxHCC, or HHS-HCC models.

Code: A03.1
Description: Shigellosis due to Shigella flexneri
HCC (V28): No CMS-HCC V28 mapping
RAF reference coefficient: —
Billable: Yes
Payment year: 2026

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

A03.1 is the ICD-10-CM diagnosis code for shigellosis due to shigella flexneri. A bacterial infection of the intestines caused by Shigella flexneri bacteria, which spreads through contaminated food or water and causes severe diarrhea, abdominal cramps, and fever. This is a contagious disease that primarily affects the digestive system. A03.1 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering intestinal infectious diseases (a00-a09).

A03.1 is a billable ICD-10-CM code, but the current payload does not show a mapping under the CMS-HCC V28 or V24 community payment models, and none under the ESRD, Part D RxHCC, or HHS-HCC models. Do not assign risk adjustment value from this page when no source-backed mapping is shown; verify the applicable model and payment year.

Verify the specific Shigella species (flexneri) is documented in the medical record before assigning this code, as different species have different codes (A03.0, A03.1, A03.2, A03.3, A03.9).

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for A03.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Verify the specific Shigella species (flexneri) is documented in the medical record before assigning this code, as different species have different codes (A03.0, A03.1, A03.2, A03.3, A03.9)
•Document any complications such as dehydration, electrolyte imbalances, or systemic manifestations separately, as these may require additional codes