ICD-10 Code A77.41 – Ehrlichiosis chaffeensis [E. chaffeensis] (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code A77.41 – Ehrlichiosis chaffeensis [E. chaffeensis]
What it is
A77.41 identifies infection caused by Ehrlichia chaffeensis, a tick-borne bacterial illness. Use it when the record specifically names E. chaffeensis ehrlichiosis.
Clinical signs
Clinical features vary; refer to documentation. Typical findings may include fever, headache, myalgia, and a history of tick exposure, but the diagnosis should be documented by the clinician.
When to use this code
Use A77.41 when the provider documents Ehrlichiosis chaffeensis, human monocytic ehrlichiosis, or E. chaffeensis infection. Code it from confirmed diagnoses or clear assessment statements in the chart. Check documentation if the note only says “ehrlichiosis” without the organism.
Do not use for
Do not use this code for other tick-borne infections, nonspecific febrile illness, or suspected ehrlichiosis without documentation. If the organism is not identified, check documentation for a more general code.
Coding tip
Match the organism name exactly; if the chart says E. chaffeensis, A77.41 is the specific code you should select.