Overview

• More than 90% of seven popular game fish species sampled in San Diego County carried two trematode flatworms, Haplorchis pumilio and Centrocestus formosanus.
• Infected trematodes can trigger gastrointestinal distress, weight loss and lethargy, with rare cases escalating to strokes or heart attacks.
• The parasites rely on invasive red-rimmed melania snails, which have spread to at least 17 U.S. states and Puerto Rico after introduction from Southeast Asia.
• Fully cooking freshwater fish or freezing it for at least one week neutralizes the trematodes, yet a review of social-media videos showed 65% omitted guidance on these precautions.
• Authors plan to share their findings with county officials and recommend adding fish-borne trematode infections to the list of diseases doctors must report.