The number of cases of cryptosporidium, a parasite that infects humans mainly through fecal-contaminated drinking water, has now reached 77.
Most infections are in Devon, but outbreaks have also been reported in Oxfordshire and Worcestershire in the past two months.
The most serious outbreak involves faecal-contaminated drinking water in Brixham, Devon, which started earlier this month.
However, since the end of March, dozens more Britons, including children, have become seriously ill after outbreaks at petting zoos.
And those trying to escape the risk of contracting the parasite this six months by going abroad are being warned that swimming pools may not be safe either.
Cryptosporidium parasites are protected by a thick shell that allows them to survive even in chlorinated swimming pool water
Entire streets in Brixham have been infested with victims enduring days of diarrhea and painful stomach cramps, with one patient even likening it to ‘childbirth’.
Residents have been forced to boil water for more than a week to make it safe to drink, with some shops running low on bottles due to panic buying.
The source of the outbreak appears to be a damaged air valve in the water supply line, which allowed “animal waste or contaminated groundwater to enter the local supply.”
Although fecal-contaminated water is the classic way people become infected with cryptosporidium, there are other ways you can become infected with the bug.
One of these is direct contact with infected animals, a fate that appears to have befallen dozens of Britons in recent months.
At least two petting zoos, which invite families to cuddle farm animals such as lambs, have been hit by suspected cryptosporidium outbreaks in the past two months.
More than 80 people are understood to have sought legal advice after parents and children fell ill at Gannow Farm, in Worcestershire, over Easter.
Victims of the infection suffered from serious stomach ailments, with some even requiring hospital treatment.
Sophie Enright, 14, from Hollywood, near Birmingham, is among those who reported symptoms after her farm visit.
She became ill on April 9 and developed diarrhea, stomach cramps and vomiting six days after her visit to the farm.
Sophie was eventually diagnosed with cryptosporidium and lost a stone during her illness.
Her mother Emma Cleverley, 38, said she feared her daughter’s exam results would suffer because she missed so much school.
Another child, five-year-old Eli, had to be hospitalized after falling ill with cryptosporidium, with his mother Kelly Roberts saying “it could have killed him.”
“We came for a fun family day out and left with a bug that could have killed him,” she told the newspaper Sun.
She added: ‘It was just horrendous to see my son hooked up to an IV, having blood drawn from his arms and unable to drink water.’
The UK Health Security Agency (UKHSA) is investigating the farm, which has remained closed since the outbreak.
Sophie Enright, 14, (pictured) visited a farm with her mother Emma Cleverley, 38, on April 3 and became ill on April 9 with diarrhea, stomach cramps and vomiting
Sophie was prescribed anti-nausea medication and medicine to ease her stomach cramps, but four days later her symptoms had not improved
The farm itself said on Facebook that it took the welfare of its visitors “very seriously” and was cooperating with investigators.
The farm itself says on Facebook that it takes the well-being of its visitors ‘very seriously’ and is cooperating with researchers.
It added: ‘We would like to wish everyone who is unwell a speedy recovery.’
Amy Chappell, from Banbury in Oxfordshire, is another parent whose child fell ill with cryptosporidium, and said her daughter Poppy had to spend four days in hospital after a day at a farm during lambing season.
Mrs Chappell said of her daughter’s cryptosporidium infection: ‘She was constantly sick every few minutes and this went on for days.
‘After I went to the doctor, I took her to the emergency room and she was immediately admitted and put on a drip because she had lost so much fluid and she was given regular medication against nausea.
‘She was so exhausted and withdrawn she couldn’t even get out of bed to go to the toilet, it was really worrying for all of us.’
Poppy’s mother added: ‘It really affected her psychologically.
Amy Chappell, from Banbury, Oxfordshire, said her daughter Poppy became seriously ill and spent four days in hospital after a day at a farm during lambing season.
Tom Bayliss, six, and his sister Grace, two, at Hadsham Farm in Horley, Oxfordshire. It is believed they contracted cryptosporidiosis from the lambs
Hadsham Farm’s lambs were found to be negative for cryptosporidiosis, but they closed the lambing event as a precaution
‘She was so sick that now she is really worried about eating because she thinks it will make her sick and she has problems with her digestion.
‘This has had a huge impact on the whole family; we had no idea how serious this bug could be.
‘We made sure to wash our hands after handling the animals and before eating, and Poppy even wore gloves but must have picked it up afterwards.’
Fellow parent Rebecca Bayliss suspects a similar fate befell her and her six-year-old son Jake after they fell ill following a visit to Hadsham Farm in Horley.
Her daughter Grace, two, and her husband Tom, 36 – who didn’t even attend the lambing event – also later started experiencing symptoms at home.
‘It was horrible. We were all very sick. My son lost a lot of weight and almost went to the hospital because he was so dehydrated. The only way I could get him to drink was to give him lemonade,” she told MailOnline.
UKHSA warned earlier this month about the risk of cryptosporidium infection from farm visits.
UKHSA warned earlier this month about the risk of cryptosporidium infection from farm visits
Locals in Brixham, Boohay, Kingswear, Roseland and north-east Paignton in Devon were all told to boil water as a precaution
Cryptosporidium is chlorine resistant, so even swimming in pools is no guarantee against infection (stock image)
In a twist on the classic nursery rhyme, the agency wrote on social media: ‘Mary had a little lamb, its fleece was white as snow.
“But wash your hands and dry them too in case there are any cryptocurrencies in them.”
People can become infected with cryptosporidium from farm animals through contact with infected feces that they then accidentally ingest by not washing their hands thoroughly.
This can be direct contact from the animal itself or from fecally contaminated surfaces such as farm gates or the bottom of shoes.
But in a word of caution, Brits boarding these temporary pools are not a sure way to avoid the parasite.
Cryptosporidium is chlorine resistant and can survive in swimming pools for up to a week.
People recovering from an infection are urged not to swim for two weeks after their symptoms have cleared as they may still be contagious.
Such infections occur after traces of dried feces wash off an infected person’s anus and enter the water before being swallowed by an unlucky swimmer.
Infections linked to swimming pool use are believed to have caused Britain’s unusual outbreak of cryptosporidium late last year.
At the time, officials investigating the unusual cluster of cases found that the only link between the cases was that dozens of affected Britons had recently traveled to Spain and other Mediterranean countries.
Other possible routes of infection for cryptosporidium include sharing towels, using swimming pools in the UK and abroad, and food preparation.