Mexican restaurant chain Chipotle has closed several restaurants in the Oregon and Washington area due to possible E. coli contamination, according to an article on usatoday.com.

Twenty-two cases of the infection have been traced back to Chipotle restaurants in the area, which led to the voluntary closing of the eating establishments.  Three people in the Portland area have been stricken since October 14, and an additional 19 in the Vancouver and Seattle areas of Washington.

No one has yet died from the poisoning, but about one third of those reporting the disease have been hospitalized.  The Shiga toxin producing E.coli bacteria is the most common  food-borne outbreak.  Victims in these cases have ranged in age from 11 to 64 years old.

Hundreds of strains of bacteria are present in the human intestine, but most are harmless or even beneficial.  A few can cause serious health issues.

Jonathan Modie, Oregon Health Authority spokesman commented, “Many people affected with Shiga toxin E. coli may not seek health care, so the number of people made ill by this outbreak is likely more than identified.”

Six restaurants have been identified in this case, but the company has decided to close 43 of its facilities in the two states as a precautionary measure.  Chipotle operates more than 1,700 restaurants across the United States and other locations.

Chris Arnold of Chipotle Mexican Grill said in a statement, “The vast majority of these restaurants have no reported problems.  We are working with health department officials to determine the cause of this issue. We offer our deepest sympathies to those who have been affected by this situation.”

State health officials have not said which ingredient in the restaurant’s food line is causing the infections, but Chipoltle restaurants in other parts of the country have had other food safety problems as well.

At least 45 cases of salmonella poisoning were reported in Minnesota last August, and officials identified tomatoes as the cause  of the outbreak, that led to diarrehea, fever and abdominal cramps for its victims.

Later the same month, 82 customers and 17 employees were stricken with a norovirus infection at a Chipotle location in Simi Valley, California.  The restaurant was closed for a day to clean up the health code violations.

The company is now facing lawsuits arising from the incidents at both locations.