ICD-10 Code B66.4 – Paragonimiasis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B66.4 – Paragonimiasis
What it is
Paragonimiasis is an infection caused by Paragonimus lung flukes, usually acquired by eating raw or undercooked freshwater crustaceans. It primarily affects the lungs, but other organs can be involved.
Clinical signs
Common findings include chronic cough, chest discomfort, and blood-tinged sputum. Clinical features vary; refer to documentation for pulmonary or extrapulmonary involvement.
When to use this code
Use B66.4 when the provider documents paragonimiasis, paragonimus infection, or lung fluke disease. Apply it for confirmed cases or when the diagnosis is clearly established in the record. Check documentation if the note only describes exposure or suspected infection.
Do not use for
Do not use this code for nonspecific parasitic infection, pneumonia of unknown cause, or abdominal complaints without documented paragonimiasis. Do not code suspected disease unless the provider confirms it.
Coding tip
Match the code to the provider’s stated organism or diagnosis wording, and verify whether the infection is pulmonary or extrapulmonary in the chart.