Rickettsioses (A75-A79) ICD-10-CM
The A75–A79 section covers rickettsioses with 26 ICD-10-CM diagnosis codes, of which 21 are billable in fiscal year 2026. The section is organized into the 4 code ranges listed below.
Code Ranges in This Section 4 ranges · 26 codes
| Code Range | Title | Codes | Billable |
|---|---|---|---|
| A75 | Typhus fever (A75) | 6 | 5 |
| A77 | Spotted fever [tick-borne rickettsioses] (A77) | 11 | 9 |
| A78 | Q fever (A78) | 1 | 1 |
| A79 | Other rickettsioses (A79) | 8 | 6 |
The info icon previews the code ranges inside each row and its instructional notations from the official Tabular List.
About the A75–A79 Code Range
ICD-10 codes A75 through A79 classify various rickettsial infections, which include several types of typhus, spotted fevers, ehrlichiosis, Q fever, and other less common rickettsioses. These codes help identify infections caused by bacteria from the Rickettsia genus and related organisms transmitted primarily by arthropods like ticks and lice.
This range covers typhus fevers such as epidemic louse-borne typhus (A75.0), murine typhus (A75.2), and scrub typhus (A75.3). It includes spotted fevers like Rocky Mountain spotted fever (A77.0), African tick bite fever (A77.1), and other tick-borne illnesses. Ehrlichiosis, a bacterial infection spread by ticks affecting white blood cells, is coded under A77.4 and its variations like ehrlichiosis chaffeensis (A77.41). The chapter also incorporates Q fever (A78), a disease caused by Coxiella burnetii, which can lead to pneumonia, hepatitis, and endocarditis.
Additionally, other rickettsial diseases such as trench fever (A79.0) and rickettsialpox (A79.1) are covered, along with specific infections like anaplasmosis (A79.82) and Sennetsu fever (A79.81). These codes are critical for accurately documenting infections caused by various rickettsiae, facilitating appropriate diagnosis and treatment. Common synonyms like Rocky Mountain spotted fever, Brill-Zinsser disease, and Q fever myocarditis align with specific codes, aiding coders interpreting clinical notes mentioning these alternate names.
Questions About This Page
How many codes are in the A75-A79 range?
The A75-A79 range contains 26 ICD-10-CM diagnosis codes in FY 2026. 21 of them are billable, and the rest are category headers that organize the section.
What conditions does A75-A79 cover?
The range covers rickettsioses. The code ranges listed above break it into groups of related conditions, and each one links to its own page with the full code list.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
