Public health officials in King County, Washington have completed their investigation into a Salmonella outbreak linked to an IHOP restaurant in Bellevue, Washington. The outbreak resulted in 33 confirmed cases, 6 hospitalizations, and no deaths over a period spanning from October 2023 to September 2024.
Outbreak Origins and Contamination Source
The outbreak began with contaminated diced onions that were part of a nationwide Salmonella contamination incident in 2023. These onions were delivered to the Bellevue IHOP location and subsequently caused illness among customers. The contaminated onions were recalled and disposed of in October 2023 following the national recall notice.
Despite the removal of the original contaminated onions, people continued to become ill with the same strain of Salmonella until June 2024. This extended timeline indicated that the bacteria had established a presence within the restaurant environment and persisted on various surfaces. National Salmonella law firm Ron Simon & Associates says that Salmonella can survive for extended periods on multiple materials.
Case Details and Demographics
Of the 33 confirmed cases, 23 individuals became sick after eating at the IHOP location, including one restaurant employee who consumed food at the restaurant. The connection between the restaurant and the remaining 10 cases could not be definitively established. The affected individuals ranged in age from 1 to 78 years old, with illness onset dates spanning from October 23, 2023, to September 9, 2024. The meals associated with illness were consumed between October 16, 2023, and June 27, 2024.
Public Health Response and Restaurant Actions
Public health officials initiated their investigation in January 2024 after identifying three Salmonella cases linked to the contaminated onions. During their initial restaurant visit, investigators confirmed that all recalled onions had been properly removed in October 2023 and found no additional food safety concerns at that time. The restaurant conducted deep cleaning procedures and provided food safety training for workers.
The investigation was reopened in March 2024 when another individual became ill after dining at the location. Environmental testing conducted on April 2, 2024, detected Salmonella on restaurant surfaces, confirming ongoing contamination. This discovery led to the restaurant’s closure on April 10, 2024, for comprehensive cleaning and disinfection. The establishment reopened on April 12, 2024, after officials verified that thorough cleaning had been completed.
Additional illnesses in May and July 2024 prompted further closures and more intensive remediation efforts. The restaurant closed again on May 24, 2024, reopening on June 7, and experienced a final outbreak-related closure on June 27, with reopening occurring on July 6, 2024.
During this period, officials implemented enhanced measures including deeper cleaning procedures, surface and equipment refurbishing to improve cleanability, and mandatory quarterly environmental testing. All restaurant workers underwent voluntary testing, which identified one asymptomatic employee who tested positive for Salmonella. This worker was required to produce two negative test results before returning to work, and the restaurant implemented additional protocols to prevent sick employees from working.
Laboratory Confirmation and Current Status
Laboratory analysis using DNA fingerprinting through whole genome sequencing confirmed that most affected individuals had the same strain of Salmonella Thompson. Environmental testing on April 2, 2024, detected the identical strain on restaurant surfaces, confirming the ongoing contamination at that time.
The last known case involved an individual who became ill after eating at the restaurant before the June 27, 2024, closure, with this case identified in October 2024. No new Salmonella cases have been reported since that time. The restaurant currently maintains a “Good” inspection rating, and public health officials have declared the investigation complete, noting that IHOP staff and management cooperated throughout the investigation process.
