E. coli outbreak 2015: Chipotle suffers four-month low sales after closing 43 restaurants

As of Nov. 2, Monday, there have been 22 cases of people who have fallen ill because of a reported E. coli outbreak in the Pacific Northwest, as per epidemiologists from the Washington state.

The outbreak is linked to Chipotle restaurants within the area, with three people from Portland and 19 people in western Washington reported sick as of Friday. Seventeen of those affected said they have been to the Mexican fast food chain within the past few weeks, eight of whom were taken to the hospital for treatment, the ABC News reported.

In light of this food safety issue the food company is faced with, the shares of Chipotle Mexican Grill Inc. has plummeted to its lowest level since July. They had to close down 43 of their branches from the states of Washington and Oregon to comply with an ongoing investigation involving the E. coli food poisoning outbreak.

According to a Reuters report, shares were at a low of $608.52 in early trading on Monday and closed down 2.5 percent at $624. There have been concerns from investors and analysts who believe that this food safety issue could take a toll in the number of customers from 1,900 restaurants in the country.

Meanwhile, an Oregon Public Health Division official said Monday that the outbreak's likely source could be a contaminated produce.

"We are looking at everything but our epidemiology investigation is guiding us toward produce," Oregon Public Health Division spokesperson Jonathan Modie said. "Chipotle has meat products, but based on things we heard from people who got sick, it seems like the most common denominator is some kind of vegetable course."

On the one hand, Chipotle spokesman Chris Arnold said that it is best not to make any assumptions that could pre-empt the investigation, the USA Today wrote. "Produce is certainly a possibility, but we are not going to speculate on what the cause may be while the investigation is going on," he said. "Right now, getting through the investigation is the priority and we continue to offer our full cooperation as that moves forward."

The Washington state Department of Health said that they have yet to confirm the cause of the E. coli outbreak. The agency also admitted that it would be hard to give an accurate number of infected people because some of them may opt not to seek medical help.

In the latest tally of affected people from E. coli, one woman has also been reported to have filed a lawsuit Tuesday against the company after eating a bowl of burrito at Chipotle in Vancouver.