Rickettsioses (A75-A79)

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.