ICD-10 Code B66.3 – Fascioliasis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B66.3 – Fascioliasis
What it is
B66.3 identifies fascioliasis, a parasitic infection caused by Fasciola liver flukes. It usually affects the biliary system and liver, and you should code it when the diagnosis is documented.
Clinical signs
Clinical features vary; refer to documentation. Commonly reported findings include abdominal pain, fever, malaise, eosinophilia, and signs of hepatobiliary involvement.
When to use this code
Use B66.3 when the provider documents fascioliasis, liver fluke infection, or Fasciola infestation. Apply it for confirmed infection and for encounters focused on evaluation or follow-up of the documented condition. If the record only suggests exposure, check documentation before coding.
Do not use for
Do not use this code for nonspecific abdominal symptoms or liver disease without a documented parasitic cause. Do not assume fascioliasis from travel history, eosinophilia, or imaging alone.
Coding tip
Code the confirmed parasitic diagnosis exactly as documented and query if the record does not clearly identify Fasciola infection.