An unprecedented Salmonella outbreak at a poultry farm in Belgium has sickened at least 306 people after they consumed eggs, the country’s food safety agency announced today.

The agency said those who developed symptoms were infected with a strain identified at the farm. However, many more people may have fallen ill without being tested because their symptoms were mild or because they experienced no symptoms at all, a spokesperson for Belgium’s food safety agency, known as AFSCA, said.

“Salmonella is relatively common in Belgium, but we have never had such a large outbreak, with so many people becoming ill,” the official said, adding that there have been no deaths.

AFSCA initially detected the contamination in May, issued a recall and shut down a goose-breeding unit at a farm in Flanders, in northern Belgium. As more cases were identified, the entire farm was closed and the birds were culled following a second recall on August 10.

The company that marketed the eggs was identified as Laerco BV. The company has not yet responded to a Reuters request for comment.

As many as 2 million eggs potentially contaminated with the bacterium were sold in Belgium and neighboring Luxembourg, where the local health authority also issued a recall order.

Some of these eggs may still be in people’s kitchens and could lead to additional cases despite the recall, the AFSCA spokesperson warned.

Cooking eggs reduces the risk of contracting the disease.