Public health authorities are investigating 47 illnesses from scombrotoxin fish poisoning linked to yellowfin tuna that may have been sold fresh or frozen.

The FDA recommends throwing out the tuna, also called ahi tuna, imported from Truong Phu Xanh Co. of Vietnam. The investigation with state health officials identified the company as the common supplier of tuna likely eaten by most of the ill people. The fish might have come as ground tuna meat, poke cubes, steaks or loins, and some products may not have expired yet.

The FDA asked the business to recall the tuna associated with most of the illnesses, which happened in late summer through mid-October. But the company hasn’t recalled any, the agency says.

The situation prevented the FDA from using its authority to mandate a recall because the illness is temporary and can go away with treatment. Scombrotoxin poisoning occurs when fish begins to spoil, increasing histamine levels. Histamine, which can’t be destroyed by freezing or cooking, can cause symptoms similar to an allergic reaction, including face flushing, itching and diarrhea.

The FDA has told field staff that they may hold the firm’s yellowfin tuna without examining it.  “Detained product will not enter the United States unless the importer proves that it meets U.S. food safety standards,” the agency’s announcement says.

As part of the investigation, FDA evaluated the firm’s HACCP plan and identified deficiencies. The agency asked the Truong Phu Xanh Co. to recall all imported yellowfin tuna produced in 2019.

The FDA has collected samples of the fish for testing throughout its investigation. Products imported from Truong Phu Xanh Co. had positive results for decomposition or high histamine levels.

Officials used traceback information to work with companies throughout the supply chain to recall products. Despite those recalls at various points in the chain, additional fish may be on the market that could make people sick, the agency says.

Importers, suppliers and distributors should discard or destroy any tuna from the company, and restaurants and retailers should contact suppliers to confirm the source their yellowfin tuna, the FDA says. Not all the fish was distributed in packaging that indicates it’s from Truong Phu Xanh Co.

One of the ill people needed to go to the hospital. Here are the number of illnesses by state:

Delaware, 6

Massachusetts, 2

Maryland, 4

New Jersey, 2

New York, 5

Ohio, 11

Pennsylvania, 6

Rhode Island, 3

Vermont, 7

West Virginia, 1

Visit the FDA’s industry and consumer assistance page for more information.