Ehrlichiosis chaffeensis [E. chaffeensis]

This code represents an infection caused by the bacterium Ehrlichia chaffeensis, a tick-borne pathogen. It is a form of human monocytic ehrlichiosis (HME), characterized by fever, headache, malaise, and often a rash, with laboratory findings typically showing leukopenia, thrombocytopenia, and elevated liver enzymes.

Use this code when documentation explicitly states a confirmed diagnosis of ehrlichiosis due to E. chaffeensis. This typically follows positive serological tests (e.g., IFA, ELISA) or molecular tests (e.g., PCR) identifying the specific pathogen. It is appropriate for both acute and resolving cases where E. chaffeensis is the causative agent.

• Ensure the documentation specifies E. chaffeensis as the causative organism; do not use for unspecified ehrlichiosis or other Ehrlichia species.
• Consider co-occurring tick-borne infections (e.g., Lyme disease, anaplasmosis) and code them separately if documented.
• Review laboratory results and physician notes for definitive identification of the pathogen to support this specific code.