ICD-10 Code B66.5 – Fasciolopsiasis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B66.5 – Fasciolopsiasis
What it is
B66.5 identifies fasciolopsiasis, an intestinal infection caused by the giant intestinal fluke Fasciolopsis buski. Use it when documentation confirms this specific parasitic disease.
Clinical signs
Clinical features vary; refer to documentation. Reported findings may include abdominal pain, diarrhea, nausea, malabsorption, or signs of intestinal irritation in confirmed cases.
When to use this code
Use B66.5 when the provider documents fasciolopsiasis, fasciolopsis infection, or giant intestinal fluke infestation. It applies to confirmed diagnosis, not merely exposure or suspected parasitic disease. If the record only says “intestinal parasite,” check documentation for the exact organism.
Do not use for
Do not use this code for other helminth infections, nonspecific intestinal parasitosis, or symptoms without a confirmed diagnosis. Check documentation if the parasite species is not identified.
Coding tip
Code B66.5 only when the organism is specifically documented as Fasciolopsis buski or fasciolopsiasis.