2027 ICD-10-CM Diagnosis Code A79.89Other specified rickettsioses

ICD-10-CM Codes›A00–B99›A75-A79›A79

ICD-10-CM A79.89
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

A79.89 is a billable ICD-10-CM diagnosis code for other specified rickettsioses. 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 15 closely related codes. Coders also document this condition as bacillary angiomatosis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Parasitic, other specified and unspecified infections.

Code Identity

ICD-10-CM Code
A79.89
Billable Status
Yes — Valid for Submission
Code Describes
Other specified rickettsioses
Short Description
Other specified rickettsioses
Same as the full description in the CMS dataset.
Parent Code
A79.8
Other specified rickettsioses

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA75-A79Rickettsioses
CategoryA79Other rickettsioses
This CodeA79.89Other specified rickettsioses

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Bacillary angiomatosis
  • Cutaneous and mucocutaneous bartonellosis
  • Infection caused by Orientia
  • Neorickettsiosis
  • Pseudotyphus of California
  • Salmon poisoning disease

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to A79.89: 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 INF009
Parasitic, other specified and unspecified infections
Default principal diagnosis: inpatient Yes · outpatient Yes

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 A79.89 to ICD-9-CMHistory

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

ICD-9-CM
083.8 Rickettsioses NEC
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 A79.89Overview

What is the ICD-10 code for other specified rickettsioses?

The ICD-10-CM code for other specified rickettsioses is A79.89 (sometimes written as A7989). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is A79.89 (Other specified rickettsioses) a billable code?

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

What MS-DRG does A79.89 group to?

When other specified rickettsioses 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 A79.89 a CC or MCC?

CMS lists A79.89 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 15 closely related codes in its exclusion list.

What is the ICD-9 equivalent of A79.89?

Under the General Equivalence Mappings, other specified rickettsioses converts to ICD-9-CM 083.8 (rickettsioses NEC). The mapping is approximate, so confirm the match fits the documentation.