At least 306 people have been infected with salmonella in Belgium after they ate eggs, according to figures released by the Belgian Federal Agency for the Safety of the Food Chain (FASFC).The outbreak has been linked to eggs produced by Laerco, a company based in Geel in northern Belgium. Salmonella was first detected at the facility at the end of April. The following month, a large-scale recall saw all eggs from the site withdrawn from the market.Contamination spreadsAt first, the contamination appeared to be confined to one of the company’s four henhouses, but the number of new cases did not fall as expected.New laboratory tests subsequently detected the bacteria in a second henhouse, before FASFC decided to halt operations at the farm and launch another recall of potentially contaminated eggs.The products concerned were distributed throughout several major supermarket chains, including Colruyt, Delhaize, Aldi and Carrefour.The precautionary recall has also been extended to Luxembourg, while FASFC has notified several other European countries that may have received the eggs, including the Netherlands, France, Italy and Portugal.What is salmonella?Salmonella are a group of bacteria that can cause a gastrointestinal illness called salmonellosis. Symptoms of infection often include diarrhoea, a fever, and abdominal cramps, while more serious cases can lead to a high fever and aches. It can also be fatal in some cases.The bacteria, which live in the guts of many farm animals, can be passed to food products such as eggs during rearing, slaughtering, or processing.