A Chipotle restaurant near Boston was closed March 8, after four workers fell sick. (Reuters)

A Chipotle Mexican Grill restaurant in the Boston area closed Tuesday after employees fell ill and one tested positive for norovirus, local health officials said.

One employee of the restaurant came down with norovirus, Billerica Board of Health Director Richard Berube told USA Today.

Four Chipotle employees reported feeling sick, Chipotle spokesman Chris Arnold told the Boston Globe. Additional employees who feel ill will be tested, he added.

"After learning that four of our employees were not feeling well — none of whom worked while sick — our restaurant in Billerica, Mass., was closed for a full sanitization," Arnold said, USA Today reported.

Richard Berube, Billerica's public health director, speaks toe reporters outside the temporarily closed Chipotle restaurant. (Brian Snyder/Reuters)

The store has been cleaned, and Berube told WHDH that he expects it will reopen on Thursday

Health inspectors who visited the store on Wednesday found it to be clean, which "was consistent with the perfect health inspection score of 100 percent this restaurant received less than a week ago, on March 3," Arnold, the Chipotle spokesman, told The Post via email.

"There are no confirmed customer illnesses connected to this incident," Arnold added.

Recent food safety issues at Chipotle have put its reputation at stake. Here's a look back at which restaurants have survived food scandals in the past. (Monica Akhtar/The Washington Post)

This is the latest incident in a string of bad health-safety news for the Mexican fast-casual chain, including in December when more than 100 Boston College students became sick after eating at Chipotle. Health officials said norovirus was the cause.

In the fall, an E. coli outbreak linked to Chipotle prompted the company to temporarily shutter more than 40 restaurants in Washington and Oregon. Then another seven states reported cases of E. coli linked to the chain.

Shares of the company's stock fell more than 6 percent by Wednesday, Reuters reported.

"We suspect that investors and consumers will be sensitive to this announcement, particularly in light of the adverse news flow over the last six months at Chipotle," CRT Capital analyst Lynne Collier said in a client note, the wire service reported. "The publicity around this news announcement will be another negative data-point that may affect consumer demand."

All Chipotle stores closed on Feb. 8 for a national food safety meeting, during which company officials talked about norovirus.

"If you're feeling sick, especially if you've vomited, whether at work or at home, you need to let your manager or your field leader know right away," co-Chief Executive Officer Monty Moran said during the webcast, the Associated Press reported.

Most foodborne-disease outbreaks in the United States are caused by norovirus, according to the Centers for Disease Control and Prevention.

The highly-contagious virus can be spread through contact with an infected person or contaminated surfaces, or consuming contaminated food or water. Symptoms include stomach pain, nausea and diarrhea, and about 570 to 800 people die each year from it, according to the CDC.

[This post has been updated.]

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