Tacoma-Pierce County Department of Health reports that it is working with Washington State Department of Health (DOH) and Thurston County Public Health and Social Services to investigate 5 cases of the foodborne illness listeriosis in Western Washington. 

Four of the cases are in Pierce County. One is in Thurston County. All 5 patients were hospitalized and 3 died. All the cases were in patients with weakened immune systems in their 60s or 70s.

Genetic fingerprinting results (whole genome sequencing) indicate that these patients likely have the same source of infection. Patients became ill between February 27 and June 30, 2023.

Investigators are interviewing patients or their proxies to help identify any common exposures.