A resident of Washington state filed a lawsuit Tuesday against Chipotle Mexican Grill Inc., alleging that she contracted an E. coli infection after eating a burrito bowl at a Chipotle restaurant in Vancouver, Washington, last month. The lawsuit comes as the 1,700-outlet chain closed 43 of its restaurants in the Pacific Northwest after a reported outbreak of E. coli bacteria that is being investigated by the company and health authorities.

The woman -- identified as Charmaine Mode from Kelso, Washington -- said in court documents that she sought treatment for the infection last week after falling ill on Oct. 25 with nausea, severe diarrhea and other symptoms, the Associated Press (AP) reported.

Three people in the Portland area in Oregon  and 19 people in western Washington had reported sick with E. coli as of Friday. According to reports, 17 of them had eaten at a Chipotle restaurant during the past few weeks. Those affected by the E. coli outbreak reportedly range in age from 11 to 61. No deaths have so far been reported in the outbreak, which is the chain's third foodborne illness this year.

On Monday, authorities said that more people are being tested for E. coli as health officials are investigating the source of the outbreak linked to Chipotle restaurants. "We actually would expect there might be a jump in cases," Marisa D'Angeli, medical epidemiologist with the Washington State Department of Health, said, according to NBC News.

The official count of people reporting sick from the infection remained at 22 Monday afternoon, while Dr. Scott Lindquist, state epidemiologist for communicable diseases for the Washington State Department of Health, reportedly said about a dozen more people were being tested for the illness in Washington.

Chipotle opened in 1993 with a single location and gained prominence by promoting its use of healthy and high-quality ingredients. However, in recent months, the chain has faced other foodborne outbreaks. 

A salmonella outbreak linked to tomatoes sickened dozens of people in Minnesota in August, AP reported, citing state health officials. The company has since switched tomato suppliers. In August, public health officials in California confirmed that the norovirus affected nearly 100 customers and employees at a Chipotle restaurant in Simi Valley.

"Having three problems in a couple of months means that Chipotle is not paying attention to food safety like it should," Bill Marler, a Seattle food safety lawyer, told AP Monday.

Chipotle shares closed down nearly 3 percent Monday.