A25.9 ICD-10-CM Code: Rat-bite fever, unspecified
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FY 2026 Apr update / Certain infectious and parasitic diseases (A00-B99) / Certain zoonotic bacterial diseases (A20-A28)
A25.9
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceRat-bite fever, unspecified
Rat-bite fever is an infection transmitted through the bite or scratch of an infected rat, causing fever and other systemic symptoms. This code is used when the specific type of rat-bite fever (spirillary or streptobacillary) has not been determined.
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
N/A—
Not mapped
ACA/HHS
N/A—
Not mapped
ESRD/PACE
N/A—
Not mapped
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for A25.9 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for A25.9 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for A25.9 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for A25.9 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for A25.9 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for A25.9 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for A25.9 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 A25.9 an HCC code?
No. A25.9 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
A25.9 is the ICD-10-CM diagnosis code for rat-bite fever, unspecified. Rat-bite fever is an infection transmitted through the bite or scratch of an infected rat, causing fever and other systemic symptoms. This code is used when the specific type of rat-bite fever (spirillary or streptobacillary) has not been determined. A25.9 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).
A25.9 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.
Query the provider if the specific type of rat-bite fever can be determined, as A25.0 (spirillary) and A25.1 (streptobacillary) are more specific and preferred codes.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for A25.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.