A79.1
BillableRickettsialpox due to Rickettsia akari
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is A79.1 an HCC code?
No. A79.1 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
A79.1 is the ICD-10-CM diagnosis code for rickettsialpox due to rickettsia akari. Rickettsialpox is a rare infectious disease caused by the bacterium Rickettsia akari, typically transmitted through mite bites. It causes fever, rash, and other flu-like symptoms. A79.1 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering rickettsioses (a75-a79).
A79.1 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
Verify the causative organism is specifically Rickettsia akari, as other rickettsial infections have different codes (e.g., A79.0 for Q fever).
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for A79.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify the causative organism is specifically Rickettsia akari, as other rickettsial infections have different codes (e.g., A79.0 for Q fever)
- •Document the source of infection (mite exposure) when available, as this may support medical necessity and help with epidemiological tracking