B66.0 ICD-10-CM Code: Opisthorchiasis
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) / Helminthiases (B65-B83)
B66.0
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceOpisthorchiasis
An infection caused by the Opisthorchis parasitic worm, typically acquired by eating raw or undercooked freshwater fish, affecting the bile ducts and liver.
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
N/A—
Not mapped
ACA/HHS
N/A—
Not mapped
ESRD/PACE
N/A—
Not mapped
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
Official- Infection due to cat liver fluke
- Infection due to Opisthorchis (felineus)(viverrini)
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for B66.0 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for B66.0 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for B66.0 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for B66.0 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for B66.0 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for B66.0 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 B66.0 an HCC code?
No. B66.0 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
Coder workflow notes
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This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
B66.0 is the ICD-10-CM diagnosis code for opisthorchiasis. An infection caused by the Opisthorchis parasitic worm, typically acquired by eating raw or undercooked freshwater fish, affecting the bile ducts and liver. B66.0 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering helminthiases (b65-b83).
B66.0 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.
Document the geographic origin or travel history, as this infection is endemic to Southeast Asia and Eastern Europe.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for B66.0 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document the geographic origin or travel history, as this infection is endemic to Southeast Asia and Eastern Europe
- •Note any complications such as cholangitis or liver dysfunction for complete coding