Officials have been unable to confirm exactly how about 175 people fell sick with norovirus at a camp in Belgium at the end of August.
An investigation into the outbreak at Breda University of Applied Sciences (BUas) involved the regional health service (GGD) West-Brabant, the Netherlands Food and Consumer Product Safety Authority (NVWA), and the Federal Agency for the Safety of the Food Chain (FASFC) in Belgium.
The introductory event organized by the higher education institution was at a campsite in Poppel, Belgium. About 900 people took part.
Symptoms appeared from Aug. 27 to 28 in young people and supervisors and included nausea, abdominal pain, diarrhea, and vomiting. A few students required brief hospitalization. Most of those affected recovered within a few days.
Stools of four sick participants were examined and were positive for norovirus.
In the week following the event, 347 participants completed a GGD survey. Although questioning revealed that certain food items were mentioned more frequently by those who fell ill, people who had not consumed these products also became ill, while others who had consumed them did not.
Investigations into the caterers and the available food also found no evidence of shortcomings or contamination.
Possible explanations for the incident include transmission from one or a few already infected individuals, food contamination by an infected person at the introductory camp, or a combination of several factors.
BUas has implemented additional hygiene and cleaning measures with extra staff and has increased the frequency of cleaning.
Recommendations for future events covered hand hygiene, cleaning, and the management of cases of illness within large groups. It is important that people wash their hands well with soap and water, especially after visiting the toilet and before preparing food. Those who are ill should stay at home and limit contact with vulnerable people.