2026 ICD-10-CM Diagnosis Code A77.9Spotted fever, unspecified
ICD-10-CM Codes›A00–B99›A75-A79›A77
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Not Chronic
A77.9 is a billable ICD-10-CM diagnosis code for spotted fever, unspecified. 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. 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 56 closely related codes. Coders also document this condition as spotted fevers. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Parasitic, other specified and unspecified infections.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Spotted fevers
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
- Tick-borne typhus NOS
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
tick-borne A77.9
Spotted fever See: Fever, spotted; A77.9
tick-borne A77.9
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
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 A77.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About A77.9Overview
What is the ICD-10 code for spotted fever, unspecified?
The ICD-10-CM code for spotted fever, unspecified is A77.9 (sometimes written as A779). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is A77.9 (Spotted fever [tick-borne rickettsioses]) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report spotted fever, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does A77.9 group to?
When spotted fever, unspecified 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.
Is A77.9 a CC or MCC?
CMS lists A77.9 as a CC (complication or comorbidity) for FY 2026. 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 56 closely related codes in its exclusion list.
What is the ICD-9 equivalent of A77.9?
Under the General Equivalence Mappings, spotted fever, unspecified converts to ICD-9-CM 082.0 (spotted fevers). The mapping is approximate, so confirm the match fits the documentation.
