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. 2025 Sep 24;88(10):100590.
doi: 10.1016/j.jfp.2025.100590. Epub 2025 Jul 31.

Paralytic Shellfish Poisoning Outbreak-Oregon, United States, 2024

Rosalie T Trevejo  1 , Matthew Hunter  2 , Terran Gilbreath  3 , Madison Walton  4 , June E Bancroft  4 , Emilio E DeBess  4 , Dat Tran  4 , Paul R Cieslak  4
Affiliations
Free article

Paralytic Shellfish Poisoning Outbreak-Oregon, United States, 2024

Rosalie T Trevejo et al. J Food Prot. .
Free article

Abstract

In May 2024, the Oregon Poison Center notified the Oregon Health Authority of multiple people with suspected paralytic shellfish poisoning (PSP) who had consumed self-harvested mussels. Two days before this report, part of the Oregon Coast was closed to mussel harvesting after detection of paralytic shellfish toxins (PST) above the closure threshold (≥80 µg PST/100 g shellfish tissue) in mussels at one site. Following these illness reports, the closure was expanded northward to the Oregon-Washington border to include harvest areas reported by ill persons. An outbreak investigation was initiated to describe the clinical characteristics and exposures, identify unreported cases, and prevent additional illnesses. Forty-two cases were identified (had paresthesia onset within 5 h of consuming shellfish), with illness onset dates during May 23-June 6, 2024, leading to 7 hospitalizations and no deaths. Persons with PSP reported exposure to mussels (35 [83%]), clams (7 [17%]), and oysters (1 [2%]) harvested from the Oregon Coast. One week after the initial PST detection, marked increases in PST levels were detected in multiple sites and shellfish types, prompting closure of the entire Oregon Coast to mussel harvesting and partial closures for clams and oysters. Leftover mussels were obtained from 3 persons with PSP; all had PST levels above the closure threshold, with one yielding the highest level (5,500 µg/100 g shellfish tissue) ever detected in Oregon shellfish. This was Oregon's largest recorded PSP outbreak. A rapid increase in PST levels over a short time presented challenges for the timely detection and closure of harvest areas. Rapid PST detection methods to supplement routine shellfish biotoxin monitoring could increase the timeliness of risk detection. Collaboration among public health officials, poison control centers, health care professionals, and shellfish program staff is essential to illness prevention and outbreak response.

Keywords: Bivalvia; Disease outbreaks; Harmful algal bloom; Marine toxins; Shellfish poisoning.

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Conflict of interest statement

Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: ‘Oregon Health Authority receives funding for programmatic activities from the Epidemiology and Laboratory Capacity Program (Centers for Disease Control and Prevention). Oregon Department of Fish and Wildlife receives funding for phytoplankton monitoring program from the National Oceanic and Atmospheric Administration (during 2007–2012, 2017–2022, and 2023–present); Northwest Association of Networked Ocean Observing Systems; and University of Washington.). The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.’.

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