VANCOUVER (CBC) - Danish health officials are continuing to hunt for the cause of a salmonella outbreak that may have sickened as many as 4,000 people.

A total of 330 cases have been confirmed but Denmark's Center for Prevention and Control of Infectious Diseases says the true number of cases is likely around 4,000. No deaths have been reported.

Common symptoms of salmonella infection include nausea, vomiting, abdominal pain and diarrhea, although more serious consequences are possible, especially in children, the elderly and those with weakened immune systems.

Kare Moelbak of the Ministry of Health said investigators suspect a Danish food product, most likely a meat product, caused the outbreak. Similar outbreaks have not been reported among neighbouring countries.

"Food control units are out to visit patients and see what they have in their refrigerators. We have even had access to electronic files to get an overview of what people have bought using their credit cards," he said.

In the U.S., 869 people have been sickened with salmonella. U.S. Food and Drug Administration investigators initially suspected tomatoes as the cause but said Wednesday they were looking at other possible causes, including vegetables commonly served with tomatoes.

With files from the Associated Press

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