A79.0 ICD-10-CM Code: Trench fever
HCC Buddy Code Card
Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.
FY 2026 Apr update / Certain infectious and parasitic diseases (A00-B99) / Rickettsioses (A75-A79)
A79.0
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceTrench fever
Trench fever is a bacterial infection transmitted by body lice that causes recurring episodes of fever, headache, and body aches. It was historically common among soldiers in trenches but can still occur in crowded, unsanitary living conditions.
CMS-HCC V28
00
RAF 0
CMS-HCC V24
00
RAF 0
ACA/HHS
00
RAF 0
ESRD/PACE
00
RAF 0
RXHCC
00
RAF 0
Code Trumping
Basket needed
Code Book Path
Inclusion Terms
Official- Quintan fever
- Wolhynian fever
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for A79.0 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for A79.0 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for A79.0 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for A79.0 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for A79.0 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for A79.0 in this effective period.
Buddy Documentation Tip
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is A79.0 an HCC code?
No. A79.0 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
A79.0 is the ICD-10-CM diagnosis code for trench fever. Trench fever is a bacterial infection transmitted by body lice that causes recurring episodes of fever, headache, and body aches. It was historically common among soldiers in trenches but can still occur in crowded, unsanitary living conditions. A79.0 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering rickettsioses (a75-a79).
A79.0 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 diagnosis is confirmed by clinical presentation and/or serological testing for Bartonella quintana before coding.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for A79.0 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify the diagnosis is confirmed by clinical presentation and/or serological testing for Bartonella quintana before coding
- •Document the patient's living conditions or exposure history (homelessness, crowded shelters, poor hygiene) as this supports medical necessity and helps explain the diagnosis