27 new cases have been confirmed in a cryptosporidium outbreak linked to a farm shop in Cowbridge.
Public health officials say at least 16 people were taken to hospital for at least one night as a result.
A total of 74 cases have been confirmed - and the number of hospital patients is expected to grow in the next week due to the incubation period.
A specialist outbreak control team met on Thursday to discuss the outbreak, linked to feeding and petting activities with young calves and lambs at Marlborough Grange Farm, which have since been stopped voluntarily.
Su Mably, a health protection consultant at Public Health Wales (PHW), said: “Although cryptosporidium infection is usually mild and clears up on its own, it can cause more serious illness in young children and people with weakened immune systems.”
"If you visited the farm and feel unwell, please contact your GP or call NHS 111. It is possible for this infection to be passed on from one person to another. It is important to protect yourself by washing your hands well, particularly before preparing food."
Cryptosporidium is a parasite that can cause gastrointestinal illness. It is often linked to contact with animals, especially young farm animals such as calves and lambs.
It can last for up to a fortnight and symptoms usually begin around two to ten days after contact.
The main symptoms of cryptosporidium include watery diarrhoeam, stomach pains or cramps, nausea or vomiting, a loss of appetite and weight loss and mild fever.
Public Health Wales says it advises anyone visiting farms to follow good hygiene practice, such as washing your hands throughly after touching animals, boots or clothing and before eating or drinking.
They advise parents to supervise children closely to ensure they wash their hands properly while pregnant women should take particular care and avoid contact with newborn lambs during the lambing season.
PHW added that it’s continuing to work alongside Vale of Glamorgan Council and the Cardiff and Vale University Health Board as part of their investigation into the outbreak.
The owners of the farm shop have made no public comment.

New details have emerged of a new tree-lined public square that will replace a traffic dominated junction. v.1
Dyffryn Gardens’ Edwardian rose garden blooms again after decade-long restoration
Barry’s Own Daniel White to Walk 190 Miles Back to Where His Round Table Story Began
1,300 people attend Flying Start Family Fun Day
Dispersal order put in place to tackle anti-social behaviour
Interim Chief Executive Appointed at Cardiff and Vale University Health Board
Cardiff Theatre Marks 50 Years of Service for Long‑Standing Staff Member
Council to review use of GP letters as evidence for disability claims
Plans have been put in place to redevelop a complex with more than 20 flats
Vale Council Reaccredited Under White Ribbon Scheme as Part of Ongoing Work to Tackle Violence Against Women and Girls
Two Vale Restaurants Among Those Set to Close as Whitbread Shuts Brewers Fayre and Beefeater Chains
Vale Council Issues Safety Warning After Gas Canisters Found in Household Recycling
Cogan Primary School Praised for its Inclusive Culture and Strong Leadership in Estyn Inspection
Senedd Members Call to Tackle Substance Use Stigma
Calls for Welsh Government to Match England's Pub Business Rates Cut
Caerdydd Penarth MS backs campaign to make rail station more accessible
Barry Waterfront Regeneration Project Moves a Step Closer
Age Cymru Responds to VAT cut to household electricity bills
Old Post Office in St Brides Major could be converted into a new house and set of flats