At least 90 people contracted an infectious bacterial disease after eating at a Provo restaurant during the Labor Day weekend, according to Dr. Joseph Miner, director of the Utah County Health Department.

The outbreak of shigellosis contamination, commonly referred to as shigella, appears limited to people who ate at Garcia's Mexican Restaurant during that weekend, Miner said."People eating there since Labor Day have not gotten sick," Miner said. "We don't think we are getting new cases."

Garcia's managers and employees are cooperating fully with the Health Department's investigation of the problem, Miner said. Because the outbreak appears limited to the Labor Day weekend, the restaurant has not been closed.

Wally Schwab, regional manager for Garcia's, also said the restaurant is working closely with the Health Department to identify the cause of the outbreak. "Our food-preparation process has been approved by the Board of Health and we are working with them to determine the cause of the isolated incident," Schwab said.

The Health Department has tested numerous employees to see if they are carriers of the disease. So far tests results have been negative, although additional employees will be tested.

Shigella is picked up through contact with infected human feces and is passed by human contact to food or other people. The incubation period for the disease ranges from one to seven days, but symptoms usually appear within four days.

Symptoms, which range from mild to severe, include abdominal cramps, fever, chills, diarrhea, headache, exhaustion, nausea and dehydration.

Utah Valley Regional Medical Center contacted Miner after identifying as many as two dozen people with confirmed cases of shigella the weekend of Sept. 7-8. Two to three people who contracted the disease required hospitalization.

"In talking to these people we found the weekend before - Labor Day - they had eaten at Garcia's Restaurant," Miner said.

Miner suspects the disease was spread during preparation of a cold food, such as lettuce or salsa. "By the time we were notified of what was happening, the food served was no longer available and we didn't get food samples," Miner said.

Shigella is highly infectious.

"Only 10 to 100 organisms can cause an infection," Miner said. In comparison, it takes 10,000 to 20,000 salmonella organisms to cause an infection.

Individuals with shigella are contagious for up to three weeks after being infected, according to Clark Caras, spokesman for the medical center.

One case has been reported where parents contracted shigella and then passed it on to a child, Miner said.

"Patients are considered infectious unless treated for 72 hours with an antibiotic," Caras said. The antibiotics effective in treating shigella are Bactrim/Sepra and Ciprofloxan.

However, people with mild symptoms may not require medical treatment and will fight off the infection naturally in three weeks, Miner said. But there is a possibility that some individuals may become chronic carriers of shigella.

"Even though they are no longer ill they may carry the bacteria for months," Miner said.

Infected people should not prepare or serve food at home or in a restaurant, Miner said. Carefully washing hands before preparing or handling food and using utensils when serving food can help limit the spread of shigella.

This is the first widespread outbreak of an infectious disease in the eight years Miner has directed the Health Department.