“There is no confirmed source and no causal relationship among the cases,” said David Hass, a health department spokesman.

Such outbreaks are extremely common and have many possible causes including environmental factors, food or food handling, he said. Health department personnel have taken food histories from those affected.

Five people initially complained of vomiting and diarrhea, including two who were hospitalized at Good Samaritan Hospital. One of those reported his illness to the Daily Herald, where the story first appeared.  All have since recovered, Hass said.

Another four people reported becoming ill in recent days. “A person may not report it for a couple of days and, in many situations, people don’t report it at all,” he said.

Health Department sanitarians have investigated food safety practices of the area restaurants and food service establishments in question. They also have run tests for common food-borne illnesses, all of which came back negative, Hass said.

“As time passes it gets harder to establish causal relationships,” he said.