93 Sick After Shigella Outbreak at California Restaurant

— -- California health officials are investigating a bacterial outbreak after at least 93 people were sickened.

An outbreak of shigella occurred at the Mariscos San Juan Restaurant on 4th Street in San Jose, California, the Santa Clara County Public Health Department said. Individuals started to report symptoms including fever, abdominal pain and diarrhea last Saturday, health officials said. Currently, at least 24 of those sickened have been diagnosed with shigella, according to the health department.

The restaurant was closed on Sunday and health department officials are asking anyone who has eaten at the restaurant and developed symptoms, including fever or sudden onset of diarrhea, to see a doctor immediately. No specific source of contamination has been identified, according to the health department.

Health department officials said many of those who had been in the intensive care unit had been discharged, but they were warning anyone with symptoms to stop working to curb the infection.

Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center, said officials would be especially concerned about improper food handling or if the produce was contaminated with polluted water.

"If produce comes in from the developing world, on occasion fresh produce has been irrigated or freshened with polluted water," he explained.

The bacteria shigella can cause an infection called shigellosis, and symptoms usually appear one to two days after a person has been exposed to the bacteria, according to the U.S. Centers for Disease Control and Prevention. Symptoms including diarrhea, fever and abdominal pain, and it usually resolves itself between five to seven days, though in rare cases the disease can be so dehydrating it can lead to dangerous complications. Young children, the elderly and those with compromised immune systems are at heightened risk for complications.

"This is serious business. It is a highly infectious agent," Schaffner said. "It usually takes very little [bacteria] to make people sick. ... That may account in part for the large number of [patients in] the outbreak."

Every year, 500,000 Americans are sickened with shigella, according to the CDC.

Mariscos San Juan Restaurant did not immediately respond to ABC News' calls seeking comment.