Dozens of people suffer from Norovirus-like symptoms after attending a major Lego event in Bristol over the weekend.
The organizers of the show at Bristol Brick say they are "devastated" and the city authorities have launched an investigation.
Almost 4,000 people visited the Action indoor sports center on the occasion of Lego, but after the event over 40 participants began to feel sick and diarrhea.
One Lego fan who wants to remain anonymous said he is not happy with the cleanliness of the place.
He said: "The condition of this place leaves much to be desired."
"The food was not great and over the weekend, the toilets were not well maintained, the sinks did not work well and there was no hand disinfection etc."
"It has affected at least 40 people I know about."
The Bristol Brick exhibition published a post on its Facebook page on Wednesday afternoon, which read: "Thank you all for coming to our concert, enjoying it and helping to raise money for two very worthy charities.
"We have been made aware that many people who have participated in our event have since been affected by the virus.
"Unfortunately, no diseases were reported during the program, so we had no way of warning anyone or identifying the source at that time.
"Many of you know that Bristol has recently seen many cases of Norovirus attacking schools, hospitals and other businesses in the area, and the combination of this plus nearly 4,000 people through our door over the weekend contributed to the outbreak.
"Last year we had the same event in the same place without any known problems, so we're sure it's an unfortunate and isolated incident.
"As organizers, we are devastated that this hindered a successful performance, of course we all wish you a speedy recovery.
"Thanks for your continued support and we hope that your memories of the show are not contaminated by these events!"