Public health officials in Seattle are investigating an outbreak of three people infected with Shiga toxin-producing E. coli O157:H7. Three people from three separate households reported becoming ill. Cases have been among people ranging in age from 18 to 36 years old.

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 other sources cannot by ruled out 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.

All three people developed one or more symptoms consistent with E. coli infection, including diarrhea (often bloody), abdominal cramping, nausea, and vomiting. Patients had illness onset dates from Sept. 21 and Oct. 12. All the patients are from separate households.

Public health officials are conducting interviews with sick people to identify any common exposures and provide guidance to help prevent further spread. 

On Nov. 2, 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 E. coli 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 and the 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.

All of the patients 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.

about E. coli infections

Anyone who has developed symptoms of E. coli infection should seek medical attention and tell their doctor about their possible exposure to the bacteria. Specific tests are required to diagnose the infections, which can mimic other illnesses.

The symptoms of E. coli infections vary for each person but often include severe stomach cramps and diarrhea, which is often bloody. Some patients may also have a fever. Most patients recover within five to seven days. Others can develop severe or life-threatening symptoms and complications, according to the Centers for Disease Control and Prevention (CDC).

about 5 to 10 percent of those diagnosed with E. coli infections develop a potentially life-threatening kidney failure complication, known as a hemolytic uremic syndrome (HUS). Symptoms of HUS include fever, abdominal pain, feeling very tired, decreased frequency of urination, small unexplained bruises or bleeding, and pallor. 

Many people with HUS recover within a few weeks, but some suffer permanent injuries or death. This condition can occur among people of any age but is most common in children younger than five years old because of their immature immune systems, older adults because of deteriorating immune systems, and people with compromised immune systems such as cancer patients. 

People who experience HUS symptoms should immediately seek emergency medical care. People with HUS will likely be hospitalized because the condition can cause other serious and ongoing problems such as hypertension, chronic kidney disease, brain damage, and neurologic problems.