Spotted fever [tick-borne rickettsioses] (A77) ICD-10-CM
The A77 code range covers spotted fever [tick-borne rickettsioses] with 11 ICD-10-CM diagnosis codes. 9 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Codes in the A77 Range 11 codes · 9 billable
- A77 Spotted fever [tick-borne rickettsioses]Non-billable
- A77.0 Spotted fever due to Rickettsia rickettsii
- A77.1 Spotted fever due to Rickettsia conorii
- A77.2 Spotted fever due to Rickettsia siberica
- A77.3 Spotted fever due to Rickettsia australis
- A77.4 EhrlichiosisNon-billable
- A77.40 Ehrlichiosis, unspecified
- A77.41 Ehrlichiosis chaffeensis [E. chaffeensis]
- A77.49 Other ehrlichiosis
- A77.8 Other spotted fevers
- A77.9 Spotted fever, unspecified
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the A77 range.
Anaplasma
A genus of gram-negative bacteria whose organisms are obligate parasites of vertebrates. Species are transmitted by arthropod vectors with the host range limited to ruminants. Anaplasma marginale is the most pathogenic species and is the causative agent of severe bovine anaplasmosis.
Anaplasmosis
A disease usually in cattle caused by parasitization of the red blood cells by bacteria of the genus ANAPLASMA.
Boutonneuse Fever
A febrile disease of the Mediterranean area, the Crimea, Africa, and India, caused by infection with RICKETTSIA CONORII.
Ehrlichiosis
A tick-borne disease characterized by FEVER; HEADACHE; myalgias; ANOREXIA; and occasionally RASH. It is caused by several bacterial species and can produce disease in DOGS; CATTLE; SHEEP; GOATS; HORSES; and humans. The primary species causing human disease are EHRLICHIA CHAFFEENSIS; ANAPLASMA PHAGOCYTOPHILUM; and Ehrlichia ewingii.
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)
Rickettsia rickettsii
A species of gram-negative, aerobic bacteria that is the etiologic agent of ROCKY MOUNTAIN SPOTTED FEVER. Its cells are slightly smaller and more uniform in size than those of RICKETTSIA PROWAZEKII.
Rocky Mountain Spotted Fever
An acute febrile illness caused by RICKETTSIA RICKETTSII. It is transmitted to humans by bites of infected ticks and occurs only in North and South America. Characteristics include a sudden onset with headache and chills and fever lasting about two to three weeks. A cutaneous rash commonly appears on the extremities and trunk about the fourth day of illness.
About the A77 Code Range
The ICD-10 code A77 and its subcodes classify various types of spotted fever caused by different species of Rickettsia bacteria and related ehrlichiosis infections. These codes are used to specify tick-borne rickettsioses, which include well-known conditions like Rocky Mountain spotted fever.
This section includes specific codes such as A77.0 for spotted fever due to Rickettsia rickettsii, commonly known as Rocky Mountain spotted fever or Western/Eastern Rocky Mountain spotted fever. Other variants include A77.1 for Rickettsia conorii infections (Boutonneuse fever, Old World tick typhus, African tick bite fever), A77.2 for North Asian tick typhus caused by Rickettsia siberica, and A77.3 for Queensland tick typhus caused by Rickettsia australis. The codes also cover ehrlichiosis, such as A77.40 for unspecified ehrlichiosis, A77.41 for human ehrlichiosis due to Ehrlichia chaffeensis, and A77.49 for other types including anaplasmosis. For less specific diagnoses, A77.8 includes other spotted fevers like Far Eastern spotted fever, while A77.9 covers unspecified spotted fever. These codes help healthcare providers accurately document and report tick-borne rickettsial infections for clinical and billing purposes.
Questions About This Page
How many billable codes are in the A77 range?
Of the 11 codes in this range, 9 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the A77 range classify?
The range classifies spotted fever [tick-borne rickettsioses]. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
