2026 ICD-10-CM Diagnosis Code A77.1Spotted fever due to Rickettsia conorii

ICD-10-CM Codes›A00–B99›A75-A79›A77

ICD-10-CM A77.1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

A77.1 is a billable ICD-10-CM diagnosis code for spotted fever due to Rickettsia conorii. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 867 through 869. Coders also document this condition as african tick bite fever. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Parasitic, other specified and unspecified infections.

Code Identity

ICD-10-CM Code
A77.1
Billable Status
Yes — Valid for Submission
Code Describes
Spotted fever due to Rickettsia conorii
Short Description
Spotted fever due to Rickettsia conorii
Same as the full description in the CMS dataset.
Parent Code
A77
Spotted fever [tick-borne rickettsioses]

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA75-A79Rickettsioses
CategoryA77Spotted fever [tick-borne rickettsioses]
This CodeA77.1Spotted fever due to Rickettsia conorii

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • African tick bite fever
  • Boutonneuse fever
  • Old World tick typhus

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • African tick typhus
  • Boutonneuse fever
  • India tick typhus
  • Kenya tick typhus
  • Marseilles fever
  • Mediterranean tick fever

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Disease, diseased
      • Conor and Bruch's (boutonneuse fever)
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • boutonneuse
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • Kenya (tick)
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • Marseilles
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • Mediterranean
        • tick
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • spotted
        • due to Rickettsia
          • conorii
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • tick
        • Mediterranean
    • Infection, infected, infective(opportunistic)
      • typhus
        • tick-borne
          • African
    • Kenya fever
    • Marseilles fever
    • Mediterranean
      • fever
        • tick
    • Mediterranean
      • tick fever
    • Typhus(fever)
      • African tick
    • Typhus(fever)
      • India tick
    • Typhus(fever)
      • Kenya (tick)

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

Clinical InformationClinical

  • Boutonneuse Fever

    a febrile disease of the mediterranean area, the crimea, africa, and india, caused by infection with rickettsia conorii.

  • Rickettsia conorii

    a species of gram-negative, aerobic bacteria that is the etiologic agent of boutonneuse fever. it resembles rickettsia rickettsii but is antigenically distinct and less virulent for animals and man. (from bergey's manual of systematic bacteriology, vol 1)

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 A77.1 to ICD-9-CMHistory

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

ICD-9-CM
082.1 Boutonneuse fever
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 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About A77.1Overview

Is A77.1 (Spotted fever [tick-borne rickettsioses]) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report spotted fever due to Rickettsia conorii on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does A77.1 group to?

When spotted fever due to Rickettsia conorii is the principal diagnosis on an inpatient stay, it groups to MS-DRG 867, 868, 869, with relative weights from 0.7297 to 2.0932 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of A77.1?

Under the General Equivalence Mappings, spotted fever due to Rickettsia conorii converts to ICD-9-CM 082.1 (boutonneuse fever). The mapping is a direct match.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.