An announcement by local health officials that they have identified at least 60 people who became sick after eating at a Chipotle Mexican Grill location in Virginia this past weekend combined with a viral video of rodents in a Dallas location Thursday to drive the company’s stock to a four-year low.

At least one of the customers of the Sterling, VA, Chipotle restaurant has tested positive for norovirus, according to David Goodfriend, director of the Loudoun County Public Health Department. The investigation is ongoing, but the restaurant reopened Wednesday. Chipotle voluntarily closed the location for cleaning on Monday.

“This provides additional information but is not sufficient to determine the cause of the outbreak. The health department is awaiting further test results, which should be available early next week,” Goodfriend said in a news release posted Thursday.

Anyone who ate at the restaurant and became ill are encouraged to contact the Health Department at 703-771-5411. Additional questions or concerns can be addressed by contacting the Health Department at health@loudoun.gov.

The news from the health department came as a video shot by a Chipotle patron at a restaurant in Dallas was burning through cyberspace. It shows three rodents, one of them crawling up the wall, in the dining area of the restaurant. Local media reported customers said the animals began falling from the ceiling while they were eating.

Denver-based Chipotle issued a statement, explaining that a small breach in the building had allowed the rodents an entry point. The company reported the breach was repaired, the rodents were removed and customers were contacted.

The corporate reassurances did little to boost investors’ confidence, with Chipotle’s stock dropping another 4.5 percent through the day to close at $356.05. That’s less than 50 percent of its all-time closing high of $757.77, which Chipotle recorded on Aug. 5, 2015.

As the price was peaking, a string of foodborne illness outbreaks was linked to Chipotle restaurants from coast to coast during the second half of 2015. The chain struggled to recover through 2016, but closed just under $380 at the end of December this past year.

Public relations and advertising campaigns have failed to work the magic promised by founder and CEO Steve Ells. The company is scheduled to report second-quarter financial information on July 25.

The string of outbreaks traced to Chipotle restaurants during the last half of 2015 included:

  • Seattle — E. coli O157:H7, July 2015, five people, source unknown;
  • Simi Valley, CA — Norovirus, August 2015, 234 people, source was sick employee;
  • Minnesota — Salmonella Newport, August and September 2015, 64 sick people, source was tomatoes but it is not known at what point in the field-to-fork chain the pathogen was introduced;
  • Nine states — E. coli O26, began October 2015 and declared over on Feb. 1, 2016, 55 people, source unknown, states involved were California, Delaware, Illinois, Kentucky, Maryland, Minnesota, New York, Ohio, Oregon, Pennsylvania and Washington;
  • Boston — Norovirus, December 2015, 151 sick people, source was sick employee; and,
  • Three states — E. coli O26, began December 2015, declared over Feb. 1, 2016, five sickened people, source unknown, states involved are Kansas, Oklahoma and Nebraska.

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