An Outbreak Investigation of Scombrotoxin Fish Poisoning Illnesses in the United States Linked to Yellowfin Tuna Imported from Vietnam-2019.

Abstract: Scombrotoxin fish poisoning (SFP) is caused by the ingestion of certain fish species with elevated concentrations of histamine due to decomposition. In fall 2019, the U.S. Food and Drug Administration (FDA) was notified of 51 SFP cases including two hospitalizations from 11 states through the FDA consumer complaint system or directly from state partners. A case patient was defined as an individual who experienced a histamine-type reaction after consumption of tuna imported from Vietnam and an illness onset between 14 August and 24 November 2019. A traceback investigation was initiated at 19 points of service to identify a common tuna source. The FDA and state partners collected 34 product samples throughout the distribution chain, including from a case patient's home, points of service, distributors, and the port of entry. Samples were analyzed for histamine by sensory evaluation and/or chemical testing. Case patients reported exposure to tuna imported from Vietnam. The traceback investigation identified two Vietnamese manufacturers as the sources of the tuna. Twenty-nine samples were confirmed as decomposed by sensory evaluation and/or were positive for elevated histamine concentrations by chemical testing. Both Vietnamese companies were placed on an import alert. Seven U.S. companies and one Vietnamese company initiated voluntary recalls. The FDA released public communication naming the U.S. importers to help suppliers and distributors identify the product and effectuate the foreign company's recall. This SFP outbreak investigation highlights the complexities of the federal outbreak response, specifically related to imported food. Cultural considerations regarding imported foods should be addressed during outbreak responses when timing is critical. Collaboration with countries where confidentiality agreements are not in place can limit information sharing and the speed of public health responses.