In October 2023, three customers of the IHOP located at 14747 NE Street, Bellevue, Washington, were infected with Salmonella after eating at the restaurant. Meal dates ranged from October 16, 2023 to December 21, 2023. Two cases were hospitalized. No one died. All three cases had the same strain of Salmonella based on whole genome sequencing at the Washington State Public Health laboratory.

Public Health Seattle King County (PHSKC) conducted interviews with the people who became sick to identify potential common exposures. They all became sick after eating at IHOP. No specific food was identified. PHSKC Environmental Health investigators visited the restaurant on January 16, 2024. Investigators reviewed the restaurant's food preparation processes and did not identify factors that may have contributed to the outbreak.

In February 2024, a fourth person was diagnosed with the same strain of Salmonella as those who became ill in 2023. On April 2, 2024, PHSKC visited the restaurant to take environmental samples. One of the samples came back positive for the outbreak strain of Salmonella. On April 12, 2024, PHSKC visited the restaurant to confirm that deep cleaning was performed. On May 24, 2024, PHSKC learned of another person with the outbreak strain of Salmonella, bringing the total number of outbreak cases to 5. The restaurant was closed as the investigation continued.

On June 27, 2024, PHSKC ordered the restaurant closed again after learning of another person who became sick after eating at the location on June 8.

On August 8, 2024, PHSKC's investigation suggested that Salmonella was introduced into this IHOP by Salmonella-contaminated diced onions that made people sick across the United States in 2024. The contaminated onions were recalled and thrown away in October 2023 at this IHOP. However, on April 2, 2024, this Salmonella strain was identified in the restaurant through environmental testing and people have continued to get sick from the same strain of Salmonella since then. This suggests Salmonella bacteria, which is known to live on surfaces like plastic and steel for a long time, is still in the restaurant, even after multiple closures, deep cleanings, and throwing away potentially contaminated food and equipment.

As of August 8, 2024, the number of outbreak associated cases was 32. Six people had been hospitalized. No one died.