2027 ICD-10-CM Diagnosis Code A25.9Rat-bite fever, unspecified

ICD-10-CM Codes›A00–B99›A20-A28›A25

ICD-10-CM A25.9
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

A25.9 is a billable ICD-10-CM diagnosis code for rat-bite fever, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 867 through 869. 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 3 closely related codes. Coders also document this condition as rat bite fever. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bacterial infections.

Code Identity

ICD-10-CM Code
A25.9
Billable Status
Yes — Valid for Submission
Code Describes
Rat-bite fever, unspecified
Short Description
Rat-bite fever, unspecified
Same as the full description in the CMS dataset.
Parent Code
A25
Rat-bite fevers

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA20-A28Certain zoonotic bacterial diseases
CategoryA25Rat-bite fevers
This CodeA25.9Rat-bite fever, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Rat bite fever

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to A25.9: its own notes plus those printed at 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 Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • diseases generally recognized as communicable or transmissible

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 Yes · outpatient Yes

Clinical InformationClinical

  • Rat-Bite Fever

    a syndrome characterized by recurring fever, rash, and arthralgias occurring days to weeks after a rat bite. the causative agents are either streptobacillus moniliformis or spirillum minus.

Patient EducationClinical

Animal Bites

Wild animals usually avoid people. They might attack, however, if they feel threatened, are sick, or are protecting their young or territory. Attacks by pets are more common. Animal bites rarely are life-threatening, but if they become infected, you can develop serious medical problems.

Read the full article at MedlinePlus

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

Convert A25.9 to ICD-9-CMHistory

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

ICD-9-CM
026.9 Rat-bite fever NOS
Exact Match The mapping is direct, with no qualifiers.

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 A25.9Overview

What is the ICD-10 code for rat-bite fever, unspecified?

The ICD-10-CM code for rat-bite fever, unspecified is A25.9 (sometimes written as A259). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is A25.9 (Rat-bite fevers) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report rat-bite fever, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does A25.9 group to?

When rat-bite fever, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 867, 869, 868, with relative weights from 0.6784 to 2.1855 depending on complications. Higher weights mean higher Medicare reimbursement.

Is A25.9 a CC or MCC?

CMS lists A25.9 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 3 closely related codes in its exclusion list.

What is the ICD-9 equivalent of A25.9?

Under the General Equivalence Mappings, rat-bite fever, unspecified converts to ICD-9-CM 026.9 (rat-bite fever NOS). The mapping is a direct match.