ICD-10 Code A77.4 – Ehrlichiosis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code A77.4 – Ehrlichiosis
What it is
A77.4 identifies ehrlichiosis, a tick-borne bacterial infection caused by Ehrlichia species. It is used when the record documents this specific diagnosis.
Clinical signs
Clinical features vary; refer to documentation. Commonly reported findings include fever, headache, malaise, myalgia, and sometimes rash or laboratory evidence of infection.
When to use this code
Use A77.4 when the provider documents ehrlichiosis by name, or when the final assessment clearly states an Ehrlichia infection. It is appropriate for confirmed cases and for encounters managed as ehrlichiosis after evaluation. If the chart only says “tick-borne illness” or the species is not specified, check documentation.
Do not use for
Do not use A77.4 for Lyme disease, Rocky Mountain spotted fever, or other tick-borne infections unless ehrlichiosis is documented. Do not code it for exposure to ticks alone.
Coding tip
Capture the provider’s exact organism or disease wording; if the record is nonspecific, query before assigning A77.4.