The CDC investigated the outbreak in 2019, 2020 and it was again reopened in Nov. 2021.
The CDC says the investigation showed that packaged salads produced by Dole made people sick.
Deaths were also reported in Michigan and Wisconsin.
Listeria symptoms can start anywhere from the same day up to four weeks after eating contaminated food. Symptoms include diarrhea, fever, muscle aches, nausea and vomiting.
Illness onset dates ranged from Aug. 16, 2014, to Jan. 15, 2022.
Data showed that bacteria from sick people’s samples over the course of more than 7 years were closely related genetically.