A cluster of E. coli cases led to the voluntary closure of many Chipotle restaurants this week. The restaurants under investigation are linked to 19 cases of E. coli illnesses in Washington. Three more cases were reported from Oregon, also associated with Chipotle restaurants. Seven of the Washington patients and one Oregon patient were hospitalized; there have been no deaths.

Four cases were reported in King County, nine in Clark County, one in Cowlitz County, and five in Skagit County. Three cases were reported in Oregon residents. While the outbreak appears to be linked to food served at Chipotle restaurants, the food or other source of contamination hasn’t yet been determined and remains under investigation. Restaurants in Washington state have voluntarily closed until further information on the cause of the outbreak is available.

Some types of E. coli can cause bloody diarrhea, abdominal cramps, fever, and vomiting. Those illnesses can sometimes result in severe, life-threatening illness and may be fatal.

“Anyone who thinks they may have become ill from eating at a Chipotle restaurant in the past three weeks should consult their healthcare provider,” said State Epidemiologist Dr. Scott Lindquist. “The elderly and very young children are more likely to become severely ill from this kind of E. coli infection.”

Local and state health officials in Washington and Oregon are investigating, working with the U.S. Food and Drug Administration, Washington State Department of Agriculture and the U.S. Centers for Disease Control and Prevention.

It is important to handle food safely. Thorough cooking will kill the bacteria and prevent illness.