(Adds Chipotle comment, context on food safety lapses)
BOSTON, July 20 (Reuters) - Testing has confirmed Norovirus in a customer who ate at the Virginia Chipotle Mexican Grill Inc restaurant that was briefly closed earlier this week following multiple reports of diners falling ill, a county health department official said on Thursday.
Shares of the burrito chain, which has been under a microscope since it was linked to a string of food safety lapses in 2015, were down 2.7 percent at $362.75 at midday on Thursday.
Chipotle has worked to win back customers and rebuild the reputation of the once-high flying chain, whose stock traded well above $700 before it was connected to E. coli, Salmonella and Norovirus outbreaks in 2015.
Stool sample tests from the diner who ate at the Chipotle in Sterling, Virginia, late last week were positive for Norovirus, said Victor Avitto, environmental health supervisor for the Loudoun County Public Health Department, which has jurisdiction over the restaurant on Tripleseven Road in Sterling.
Chipotle closed the restaurant on Monday and reopened it on Wednesday, following a deep cleaning. News of the outbreak came after diners reported symptoms on iwaspoisoned.com, a crowd-sourced website.
Chipotle expected the confirmation, since the symptoms described by customers of the Sterling restaurant were consistent with Norovirus, spokesman Chris Arnold said.
Norovirus is the No. 1 cause of illness from contaminated food in the United States, resulting in an estimated 19 million to 21 million illnesses annually, according to the Centers for Disease Control and Prevention. It is highly contagious and can spread from person to person, as well as through food prepared by an infected person. Symptoms include cramping, nausea, vomiting, and diarrhea.
(Reporting by Lisa Baertlein in Boston; Editing by Matthew Lewis and Chris Reese)