Chipotle closes dozens of stores in Washington and Oregon in E. coli scare

(CNN) Chipotle has temporarily closed dozens of its restaurants in Washington and Oregon out of an abundance of caution after an E. coli scare.

No one has died in the reported cases of infection, the Washington State Department of Health said. Seven of the Washington patients and one Oregon patient were hospitalized.

The source of contamination has yet to be exactly determined, the department said, but 19 cases in Washington and three cases in Oregon have been linked to a handful of locations of the Mexican-themed restaurant chain.

Although cases are being investigated in connection with six locations in the Seattle and Portland areas, Chipotle has temporarily closed 43 stores.

"We immediately closed all of our restaurants in the area out of an abundance of caution, even though the vast majority of these restaurants have no reported problems," said Chipotle spokesman Chris Arnold in a statement. Chipotle is working with health departments to help determine the cause of the cases.

CDC on E. coli

Infections with Escherichia coli can cause severe stomach cramps, vomiting and diarrhea which is often bloody. Fever is usually low, if at all present, according to the Centers for Disease Control and Prevention. Infections can range from mild to life-threatening.

E. coli bacteria are commonly found in human and animal intestines and are a key component of healthy digestion. Most strains are harmless but some are not, according to the CDC. "Infections start...when you get tiny (usually invisible) amounts of human or animal feces in your mouth," it says.

This happens surprisingly often, the CDC says, and many times no infection results.

Common sources of infection are human and animal contact in the farming industry. In April, at least 25 people took ill with E. coli infections after visiting a dairy fair in Washington state.

But harmful E. coli can also make its way into food ingredients. Food handlers carrying harmful E. coli can also pass it on by not thoroughly washing their hands before performing their work.

The CDC has investigated more than 20 major E. coli outbreaks since 2007. Other common food-borne ailments are caused by Listeria and Salmonella bacteria.