The victims, which included employees of the association, its members, and other guests, all suffered from the illness caused by the Shigella dysenteriae bacteria after eating in the office’s cafeteria several weeks ago, reports the Veckans Affärer magazine.
Five suffered symptoms so severe they were admitted to hospital.
The bacteria are most often spread via contaminated water and food, but an examination of the restaurant cafeteria failed to uncover the source of the outbreak.
So far no traces of the bacteria have uncovered from any of the several tests performed in the cafeteria’s kitchen.
According to Veckans Affärer, Säpo is leading the investigation in cooperation with Swedish police.
“The reason that the police want to investigate the case is that neither the department of infectious diseases nor the environmental department could ascertain the source of the infection and a group has also taken responsibility for the Shigella-outbreak on its website,” said the Confederation of Swedish Enterprise’s Marie Rudberg to the magazine.
According to the Metro newspaper, the group claiming responsibility for the attack is a left-leaning, internet-based forum which had previously staged demonstrations outside of the association’s headquarters.
Security has been stepped at the restaurant and health authorities continue working to localize the sources of the outbreak through continued interviews with around 300 people who visited the eatery over several days.