ICD-10 Code A77.0 – Spotted fever due to Rickettsia rickettsii (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code A77.0 – Spotted fever due to Rickettsia rickettsii
What it is
A77.0 identifies spotted fever caused by Rickettsia rickettsii, the agent of Rocky Mountain spotted fever. Use it when the diagnosis is documented as this specific rickettsial infection.
Clinical signs
Clinical features vary; refer to documentation. Typical findings include acute fever, headache, rash, and a history of tick exposure, but the rash may be absent early.
When to use this code
Use this code when the provider documents spotted fever due to Rickettsia rickettsii, Rocky Mountain spotted fever, or an equivalent confirmed diagnosis. It is also appropriate when the record clearly links the illness to this organism. If the chart only says “suspected” or “rule out,” check documentation before coding.
Do not use for
Do not use this code for nonspecific fever, other rickettsial illnesses, or tick-borne disease without documentation of Rickettsia rickettsii. Check documentation if the organism is not identified.
Coding tip
Code the specific documented organism name, not just the rash or tick exposure, to avoid using an unspecified infection code.