Another 19 cases of cryptosporidium have been confirmed in an outbreak linked to a farm shop in Cowbridge.
Authorities are still investigating after people who attended feeding and petting sessions with calves and lambs at the shop on Marlborough Grange Farm fell ill.
A total of 47 cases have been confirmed and Public Health Wales says it expects that number to rise in the coming weeks because of the incubation period.
The parasite can last for up to a fortnight and symptoms usually begin around two to ten days after contact.
The Cowbridge Farm Shop has stopped the public activities and they're working alongside outbreak control experts.
Su Mably, a health protection consultant at PHW, said: "We are continuing to investigate this outbreak with our partners."
"While the infection is usually mild and self-limiting, it can be more serious in young children or people with weakened immune systems."
"We urge anyone who visited the farm and is feeling unwell to contact their GP or NHS 111. Practising good hygiene is the best way to protect yourself and others."
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.
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.
PHW 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.
Local authorities including the Cardiff and Vale health board and Vale of Glamorgan Council are also investigating the outbreak.
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