The number of people who reported that they became ill after eating at the Chipotle Mexican Grill in Kent is up to 180, and health officials are continuing their investigation to determine the cause.

The restaurant at 429 E. Main St. was allowed to reopen at noon Saturday after it replaced all of its food stock and sanitized all of its equipment.

The restaurant also replaced all of its staff at the restaurant with employees from other stores.

Kent Health Commissioner John Ferlito said Saturday the health department and Denver-based restaurant chain agreed to switch employees out of concern that the outbreak might be caused by a sick employee. Several of the restaurant's employees had been ill, but they also had eaten the restaurant's food.

Ferlito said the cause of the illnesses could be something foodborne such as salmonella or could be a norovirus that started with a sick employee who contaminated the food.

It will be five days before test results of food samples and stool samples from sick customers are known, which should indicate the exact cause of the illnesses.

About 10 p.m. Thursday, people began showing up at the emergency room of Robinson Memorial Hospital with symptoms that included vomiting, diarrhea, abdominal cramps and nausea.

Over Thursday and Friday, about 50 people sought treatment at Robinson Memorial Hospital, three of whom were required to stay overnight because their symptoms were so severe.

Others were treated at Kent State's DeWeese Health Center, and others simply called the health department to report they had become ill and had treated themselves at home or saw their personal physicians.

Many of those who got ill were KSU students. The restaurant is directly across from the campus, and students who took part in a recent American Red Cross blood drive received a coupon for free food at Chipotle.

Norovirus gastroenteritis

Ferlito said Chipotle restaurants haven't had any problems at other stores and all of the food for the chain comes from the same source, which indicates the illness was specific to Kent.

Outbreaks of norovirus gastroenteritis have been traced to restaurants, cruise ships, nursing homes and other places where large numbers of people are served meals, according to the Centers for Disease Control and Prevention.

''People working with food who are sick with norovirus gastroenteritis are a particular risk to others, because they handle the food and drink many other people will consume. Since the virus is so small, a sick food handler can easily — without meaning to — contaminate the food he or she is handling. Many of those eating the contaminated food may become ill, causing an outbreak,'' according to the CDC Web site. The CDC estimates as many as half of all food-related outbreaks might be caused by norovirus.

Chipotle statement

Chipotle spokesman Chris Arnold issued the following statement Saturday: ''Local health department officials have found no violations in inspections of our Kent State restaurant conducted after this incident was first reported, and again in an inspection this morning. We have reopened our restaurant with their full support. We have taken preventative steps that meet or exceed health department requirements, and will continue to assist them in their investigation.''

Anyone who thinks they might have gotten ill from food at the restaurant is asked to call the Kent Health Department at 330-678-8109 and to seek medical attention.

Robinson Memorial Hospital also offers a 24-hour emergency line at 330-297-2850.