Summary
Public Health is investigating an outbreak of three people infected with Shiga toxin-producing E. coli O157:H7 (also known as STEC). Between October 4 – 16, 2022, 3 people from 3 separate households reported becoming ill. Cases have been among people ranging in age from 18 to 36 years old. Symptoms reported include diarrhea and abdominal pain.
The investigation is ongoing, and no source has been identified. Two of the three ill people report eating dishes that were prepared with raw or undercooked beef but we cannot rule out other possible sources at this time.
Confirmed cases have been linked through genetic fingerprinting results (whole genome sequencing) which indicate that they have the same genetic strain, meaning they likely have a common source of infection.
Illnesses
All three people developed one or more symptoms consistent with STEC, including diarrhea (often bloody), abdominal cramping, nausea, and vomiting. Cases had illness onset dates from September 21 – October 12, 2022. All the cases are from separate households.
Public Health actions
Public Health is conducting interviews with the people ill with STEC to identify any common exposures and provide guidance to help prevent further spread.
On November 2, 2022, Environmental Health Investigators visited two locations listed by some of the ill people as places they ate during their likely exposure period. Environmental Health Investigators took environmental samples (i.e. swabs) during their inspections and STEC has not been detected in the environmental samples tested so far. Additional test results are pending.
Public Health is working with the United States Department of Agriculture (USDA) and Washington State Department of Health to complete further testing, to identify related cases in other counties, and to begin traceback of products in common. Traceback is used to identify points of contamination in the food supply chain.
Laboratory testing
All of the cases have confirmatory testing indicating infections with Shiga toxin-producing E. coli O157:H7 via culture. All confirmed cases have the same strain of Shiga toxin-producing E. coli O157:H7, based on genetic fingerprinting (whole genome sequencing or WGS) at the Washington State Public Health Laboratory.