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

Compare with another code for A77.1Check this code on a claim

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
6 inclusion terms

Billable · FY2027A valid, specific ICD-10-CM code, reportable for dates of service in FY2027.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too, and is marked with where it comes from.

IncludesWhat this code covers
  • African tick typhus
  • Boutonneuse fever
  • India tick typhus
  • Kenya tick typhus

+2 more in Instructions

Where it sits Source: CMS/NCHS

Under:Chapter 1: Certain Infectious and Parasitic DiseasesA75-A79 RickettsiosesA77 Spotted fever [tick-borne rickettsioses]

CompareCheck ClaimView Related Codes

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v44, Appendix B.

  • MS-DRG 867 — OTHER INFECTIOUS AND PARASITIC DISEASES DIAGNOSES WITH MCC (MDC 18)
  • MS-DRG 868 — OTHER INFECTIOUS AND PARASITIC DISEASES DIAGNOSES WITH CC (MDC 18)
  • MS-DRG 869 — OTHER INFECTIOUS AND PARASITIC DISEASES DIAGNOSES WITHOUT CC/MCC (MDC 18)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for A77.1 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Inclusion Terms

Alternative terms the tabular list files under this code.

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

Coder workflow for A77.1

MedCoder structured workflow — derived from this code’s own official record

Before you code A77.1

  1. A77.1’s title joins a condition with an associated condition or complication. Confirm each component is documented. Where the classification presumes the link through the “with” convention, only a provider statement that the conditions are unrelated defeats it. A combination code is assigned only when it fully identifies the documented conditions; a required second code for the stage, type or manifestation is still reported when the notes ask for it (Guidelines I.B.9, I.A.15).

    Guide: Combination codes →

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
The associated condition or complication
Whether the associated condition the title names is documented; the “with” convention presumes some links, and a provider statement that the conditions are unrelated defeats it (Guidelines I.A.15).

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: Only one of the components this code’s title joins is documented.

Coding question: Is A77.1 supported?

Path: Review the code for the documented component on its own.

Reason: A combination code is assigned only when it fully identifies the documented conditions; otherwise the documented component takes its own code (Guidelines I.B.9).

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Don’t confuse A77.1 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of A77.1 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

  • A77.9— Specificity relationship (Review)

    Overlapping diagnoses in the same category.

    Overlapping codes in the same category — the documentation decides which is the more specific fit.

    What moves you there: A record that documents no more than “Spotted fever, unspecified” takes A77.9; specificity in the record moves it back here.

    Full comparison: A77.1 vs A77.9 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Spotted fever due to Rickettsia conorii is a billable ICD-10-CM diagnosis code (A77.1).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Verify Before Coding

  • CC as a secondary diagnosis (FY2027). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder-derived relationships — computed from published CMS and AHRQ datasets

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 56 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 3 MS-DRGs: DRG 867 (MDC 18), DRG 868 (MDC 18), DRG 869 (MDC 18).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):INF009 — Parasitic, other specified and unspecified infections (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

A69.21 — Meningitis due to Lyme disease, A69.22 — Other neurologic disorders in Lyme disease, A69.23 — Arthritis due to Lyme disease, A69.29 — Other conditions associated with Lyme disease, A75.0 — Epidemic louse-borne typhus fever due to Rickettsia prowazekii, A75.1 — Recrudescent typhus [Brill's disease], A75.2 — Typhus fever due to Rickettsia typhi, A75.3 — Typhus fever due to Rickettsia tsutsugamushi, A75.9 — Typhus fever, unspecified, A77.0 — Spotted fever due to Rickettsia rickettsii, A77.2 — Spotted fever due to Rickettsia siberica, A77.3 — Spotted fever due to Rickettsia australis, A77.40 — Ehrlichiosis, unspecified, A77.41 — Ehrlichiosis chaffeensis [E. chaffeensis], A77.49 — Other ehrlichiosis, A77.8 — Other spotted fevers, A77.9 — Spotted fever, unspecified, A78 — Q fever, A79.0 — Trench fever, A79.1 — Rickettsialpox due to Rickettsia akari, +35 more

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Parasitic, other specified and unspecified infections).

A69.23 — Arthritis due to Lyme disease, A69.29 — Other conditions associated with Lyme disease, A69.8 — Other specified spirochetal infections, A69.9 — Spirochetal infection, unspecified, A75.0 — Epidemic louse-borne typhus fever due to Rickettsia prowazekii, A75.1 — Recrudescent typhus [Brill's disease], A75.2 — Typhus fever due to Rickettsia typhi, A75.3 — Typhus fever due to Rickettsia tsutsugamushi, A75.9 — Typhus fever, unspecified, A77.0 — Spotted fever due to Rickettsia rickettsii, A77.2 — Spotted fever due to Rickettsia siberica, A77.3 — Spotted fever due to Rickettsia australis, A77.40 — Ehrlichiosis, unspecified, A77.41 — Ehrlichiosis chaffeensis [E. chaffeensis], A77.49 — Other ehrlichiosis, A77.8 — Other spotted fevers, A77.9 — Spotted fever, unspecified, A79.0 — Trench fever, A79.1 — Rickettsialpox due to Rickettsia akari, A79.81 — Rickettsiosis due to Ehrlichia sennetsu, +235 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Fever”, “Typhus”; these codes share that main term but sit in a different category of the Tabular List.

A48.4 — Brazilian purpuric fever (Brazilian purpuric), A68.0 — Louse-borne relapsing fever (relapsing, louse-borne), A68.1 — Tick-borne relapsing fever (mianeh), A68.9 — Relapsing fever, unspecified (relapsing), A70 — Chlamydia psittaci infections (parrot), A75.0 — Epidemic louse-borne typhus fever due to Rickettsia prowazekii (famine), A75.1 — Recrudescent typhus [Brill's disease] (recrudescent), A75.2 — Typhus fever due to Rickettsia typhi (rat), A75.3 — Typhus fever due to Rickettsia tsutsugamushi (kedani), A75.9 — Typhus fever, unspecified, A78 — Q fever (Q), A79.0 — Trench fever (Meuse), A79.1 — Rickettsialpox due to Rickettsia akari (Kew Garden), A80.4 — Acute nonparalytic poliomyelitis (polioviral), A88.0 — Enteroviral exanthematous fever [Boston exanthem] (enteroviral exanthematous), A90 — Dengue fever [classical dengue] (sun), A91 — Dengue hemorrhagic fever (dengue, hemorrhagic), A92.0 — Chikungunya virus disease (Chikungunya), A92.1 — O'nyong-nyong fever (O'nyong-nyong), A92.2 — Venezuelan equine fever (Venezuelan equine), +102 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Gamma-glutamyl Transferase (GGT) Test

Contextual Map

Every relationship of A77.1 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Hierarchy

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • MDC 18 — Infectious and Parasitic Diseases, Systemic or Unspecified Sites[MDC crossing]: “Infectious and Parasitic Diseases, Systemic or Unspecified Sites — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 1 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027

Index entries (15)

  • Disease, diseased, Conor and Bruch's (boutonneuse fever)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor), boutonneuse[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor), Kenya (tick)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor), Marseilles[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor), Mediterranean, tick[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor), spotted, due to Rickettsia, conorii[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor), tick, Mediterranean[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Infection, infected, infective (opportunistic), typhus, tick-borne, African[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • and 7 more

Nearest codes (10)

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Reference

Index terms and tables, published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Indexed Clinical Terms (15)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v44 Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder-derived relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder editorial explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "A77.1 — Spotted fever due to Rickettsia conorii." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/a77.1-spotted-fever-due-to-rickettsia-conorii

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Spotted fever due to Rickettsia conorii

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to A77.1 in its code family, with their registry titles.

View all codes in the A77 family