Chipotle in Billerica, Mass., closed its doors for a second day after one of its employees tested positive for the highly contagious norovirus that is going around the U.S. right now.  As many as four employees are suspected to be sick with the stomach bug. According to the CDC:

“Norovirus is a very contagious virus. You can get norovirus from an infected person, contaminated food or water, or by touching contaminated surfaces. The virus causes your stomach or intestines or both to get inflamed (acute gastroenteritis). This leads you to have stomach pain, nausea, and diarrhea and to throw up.

Anyone can be infected with norovirus and get sick. Also, you can have norovirus illness many times in your life. Norovirus illness can be serious, especially for young children and older adults.

Norovirus is the most common cause of acute gastroenteritis in the United States. Each year, it causes 19-21 million illnesses and contributes to 56,000-71,000 hospitalizations and 570-800 deaths. Norovirus is also the most common cause of foodborne-disease outbreaks in the United States.”

The Chipotle location, which is just northwest of Boston, shut its doors Tuesday after word emerged that at least one employee had tested positive for the norovirus.

The store is expected to reopen Thursday if the employees who come to work test negative for the virus, Richard Berube, director of the Billerica Board of Health told USA TODAY this week.

Chipotle will test the employees for the virus via stool sample and symptom questionnaire, Berube said.

The stock fell more than 5% early Wednesday but recovered somewhat in late-afternoon trading to $505.11, which represents a loss of 3.7%.