The Kansas City News reports that some test results came back on people who became mysteriously ill earlier this week while staying at The Elms Resort in Excelsior Springs.
At least 19 people became sick Monday and Tuesday with symptoms of nausea, vomiting, diarrhea and abdominal pain. Others had become ill over the weekend.
Thursday, Clay County health officials said four bacterial infections, including salmonella and E. coli, have been ruled out as the cause.
More tests will be done to determine if viral agents are to blame.
Clay County health officials want to talk to people who were at The Elms over the weekend, whether or not they became ill.