On September 26, 2018 officials at Public Health Seattle King County (PHSKC) announced an investigation of Salmonella I,4,[5],12:i: infections spanning an 11 month period associated with food prepared in the service deli at the Costco Wholesale Warehouse located in Issaquah, Washington. Seven case patients experienced illness onset between August 28, 2017 and July 13, 2018. One person was hospitalized. There were no deaths.

All 7 who got sick shopped at Costco in Issaquah; five bought ready-to-eat food from the service deli. Food purchase history could not be verified for one person and one was an employee at the deli. There is no evidence to indicate the service deli employee was the source of this outbreak.