Kajsa Eriksson at the Environmental Administration tells the radio station that the infection has also been searched for in the raw materials from the suppliers of the truffle mixture where listeria has been found, but that it has not been possible to find the source.
In mid-October, the environmental administration declared that all six different truffle samples from the restaurant contained higher levels of listeria.
Over 150 people sought care at hospitals in the Stockholm region after the outbreak.
