Health officials in Washington State said on Friday that three people had died and two had been hospitalized in the Puget Sound area after contracting food-borne listeria infections in what appeared to be an outbreak.
Testing indicated that all five patients, three men and two women, became ill between Feb. 27 and June 30 and probably had the same source of infection, officials said, though an investigation had not yet identified a common food source.
Each infected person was in their 60s or 70s and had a compromised immune system, officials said.
Four of the cases were in Pierce County, and one was in Thurston County.
The Washington State Department of Health said it was working with “local health jurisdictions to gather information from interviews with patients and their families to help identify any common exposures.”
While it was still unclear where the cases originated, officials said the bacteria were commonly found in unheated cheeses and deli meats, unpasteurized dairy products, and premade deli salads, such as potato or tuna salads.
Officials added that the microorganism would die at temperatures above 165 degrees Fahrenheit.
The illness listeriosis, caused by the bacteria listeria, is of greatest threat to older adults, people with weakened immune systems and those who are pregnant.
Listeriosis typically manifests within two weeks of consuming contaminated food and can cause flulike symptoms, according to the Centers for Disease Control and Prevention. In pregnant people, severe cases can lead to miscarriage and other complications.
Washington State records 10 to 25 cases of the infection each year, according to the Tacoma-Pierce County Health Department.
From 2009 to 2021, the latest year for which data is available, the state logged 18 listeria outbreaks that resulted in 238 hospitalizations and 47 deaths, according to the C.D.C.