More than 215 holidaymakers have launched legal action against Butlins over alleged undercooked food and slimy swimming pools that they claim left them violently ill.
Families claim they were left with severe sickness, stomach cramps and diarrhoea after just days at the holiday park in Bognor Regis, Essex.
Many raised concerns about food hygiene, including being served undercooked meals, hot food being mixed with existing trays and constant bombardment by flies and pigeons.
They also claim the water in the swimming pool was dirty and cloudy, with slime building up around the edge.
As a result of the illness families were told to leave early, while others say they were completely ignored by staff members.
Now the disgusted families have instructed law firm Irwin Mitchell to start court proceedings after Butlin’s parent company Bourne Leisure Ltd denied any liability for the outbreak between May and July 2011.
Alison Hill, 55, a group leader of Mencap Hillingdon North, visited the site for five days in June 2011 with seven other volunteers and the group’s 21 members.
The carer, from Middlesex, said: “When one of our group members became ill I complained to the resort staff, but was then seen privately by a manager who asked me not to tell other guests about the illness and also asked if the party could leave early.
“We were stunned.
“Having to return earlier than planned caused major disruption, as day-to-day carers for some of our members were on holiday themselves and did not expect us to be returning early.
“Over two years on, we have still not been on another overnight visit as a group simply because we all do not want to go through the emotional and physical distress again.
“It is really worrying that other people have also suffered illness since our time there.
“We know all too well how falling ill can ruin your holiday.”
Amy Denny, 24, from Northampton, also returned home early from her break at the resort with her partner Philip and sons Bailey and Finley.
The healthcare assistant said: “My youngest son Bailey was only 18 months at the time and we had to take him to hospital as we were so scared about the effect that the illness had on him.
“It is so upsetting that it was our first holiday together as a family and it has scarred them for life.”
Elizabeth Tetzner, of Irwin Mitchell, said: “Our clients have given us worrying accounts of their stays, including concerns regarding cleanliness, standards of food preparation and service as well as their treatment by staff at the site.
“Bourne Leisure Ltd has denied liability and as such our clients have been left with no other option than to issue court proceedings as they seek justice for their ruined holidays.
“Unless an out of court settlement can be achieved on satisfactory terms, these clients’ claims will be determined at trial in court.
“Gastric illness can have a devastating impact on people’s health and the effects of it cannot be underestimated.
“We have acted in numerous cases where our clients have been left with long term health problems.”