A Salmonella outbreak that sickened almost 200 people at a Belgian school was likely caused by eggs used to make a tartar sauce, according to authorities.

The Agency for Care and Health (Zorg en Gezondheid) and Federal Agency for the Safety of the Food Chain (FASFC) investigation detected Salmonella in the freshly prepared tartar sauce. Findings from an online survey of students and teachers also reached the same conclusion on the source.

The Agency for Care and Health had previously received information about a number of students from the school complaining of gastrointestinal illness.

Since Sept. 14, no new cases of illness have been reported so the Spermalie Hotel and Tourism School in Bruges has been allowed to resume normal operation.

About 200 students and teachers from the school became ill from Sept. 6 onward. Laboratory analyses of stool samples revealed students and teachers had been affected by Salmonella.

Online survey, sampling part of investigation

The Agency for Care and Health handled the online survey part of the investigation, FASFC took samples of meals served on Tuesdays, Wednesdays and Thursdays at the school restaurant. The samples were sent to the lab of Sciensano, the Belgian Institute for Health.

The online survey showed the tartar sauce was the most likely source of the outbreak.

A total of 65 samples were sent to Sciensano and after analysis of the different dishes, Salmonella was detected in the freshly prepared tartar sauce. Bacteria present in the food appeared to be the same as in the stool samples from patients.

Staff and students were asked to pay particular attention to hand hygiene and those sick were encouraged to stay at home.

The kitchen of the school restaurant and all kitchens and related equipment have been cleaned and disinfected. The sale of any raw food was also suspended. Control measures have been verified by environmental sampling and no Salmonella has been detected in lab analysis of these samples.

Belgium reported 2,698 confirmed salmonellosis cases in 2016 compared to 3,050 the year before.

Symptoms of Salmonella infection can include diarrhea, abdominal cramps, and fever within 12 to 72 hours after eating contaminated food.

Otherwise healthy adults are usually sick for four to seven days. Older adults, children, pregnant women and people with weakened immune systems, such as cancer patients, are more likely to develop a severe illness and serious, sometimes life-threatening conditions.

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