A75.1 ICD-10-CM Code: Recrudescent typhus [Brill's disease]
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FY 2026 Apr update / Certain infectious and parasitic diseases (A00-B99) / Rickettsioses (A75-A79)
A75.1
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceRecrudescent typhus [Brill's disease]
Recrudescent typhus, also known as Brill's disease, is a reactivation of a previous typhus infection that occurs months or years after the initial illness. The disease is caused by the same bacteria (Rickettsia prowazekii) that causes epidemic typhus and presents with fever, headache, and rash.
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
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Code Book Path
Inclusion Terms
Official- Brill-Zinsser disease
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for A75.1 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for A75.1 in this effective period.
Excludes 1
Official- rickettsiosis due to Ehrlichia sennetsu (A79.81)
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for A75.1 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for A75.1 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for A75.1 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 A75.1 an HCC code?
No. A75.1 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
A75.1 is the ICD-10-CM diagnosis code for recrudescent typhus [brill's disease]. Recrudescent typhus, also known as Brill's disease, is a reactivation of a previous typhus infection that occurs months or years after the initial illness. The disease is caused by the same bacteria (Rickettsia prowazekii) that causes epidemic typhus and presents with fever, headache, and rash. A75.1 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering rickettsioses (a75-a79).
A75.1 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.
This code is used when a patient has a recurrence or reactivation of typhus from a previous infection, not a new primary infection—ensure documentation clearly indicates this is a recurrence.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for A75.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This code is used when a patient has a recurrence or reactivation of typhus from a previous infection, not a new primary infection—ensure documentation clearly indicates this is a recurrence
- •Brill's disease typically occurs in patients with a history of epidemic typhus; review patient history and medical records to confirm prior typhus infection before assigning this code