Abstract
INTRODUCTION: In Spring 2024, Oregon experienced an outbreak of paralytic shellfish poisoning following ingestion of locally harvested mussels containing elevated saxitoxin concentrations. Prior outbreak reports either do not specify clinical timelines or document variable clinical courses making it difficult to risk stratify patients or determine appropriate clinical monitoring times. We examined cases from this outbreak for symptom progression information that might help guide Poison Center recommendations on management. METHODS: This was a retrospective chart review of cases of paralytic shellfish poisoning reported to the Oregon Poison Center during the outbreak timeframe. Cases were reviewed for time of symptom onset, duration of symptoms, timeline of symptom progression, symptom severity, disposition from the emergency department, need for ventilator support, and number of shellfish ingested. RESULTS: Of eighteen cases reported to the Oregon Poison Center that met the case definition, one was excluded due to insufficient clinical data. Of the seventeen remaining cases, symptom onset occurred as late as 3.5 hours after exposure. Nine cases demonstrated progression of symptoms after initial healthcare contact. All progression to severe symptoms occurred within 6 hours of ingestion. No case demonstrated symptomatic progression beyond 13 hours. There were no deaths. Thirteen cases had a documented number of shellfish ingested, and most had“moderate” symptoms. CONCLUSION: This case series demonstrated symptom onset up to 3.5 hours after exposure and significant symptom progression within 6 hours with no symptomatic progression beyond 13 hours. These data may be useful when considering monitoring and risk-assessment of future cases.