Ohio authorities are trying to find out what has sickened hundreds of tourists and residents of a popular island getaway.

Most people say they became sick within two or three days of visiting Lake Erie (search)'s South Bass Island (search), popular for its nightlife and laid-back lifestyle. The island draws about 15-thousand people a weekend.

Symptoms that include nausea, chills, fever, abdominal cramps, diarrhea and vomiting have generally lasted about 24 hours.

An Ohio Department of Health (search) spokesman says health officials have documented 378 cases and are investigating 150 other claims of illnesses.

The department has confirmed one case of salmonella, three of norovirus -- a gastrointestinal virus -- and ten cases of campylobacter -- a common infectious disease usually coming from contaminated food or water.