An ‘explosive diarrhoea’ parasite is sweeping the world… and now it has reached the UK and Europe: Here’s how you can avoid the grim bug that grips hold of your guts for weeks and starts with a bubbling, balloon-like feeling

It’s the explosive diarrhoea bug that’s struck down tens of thousands of Americans this summer. Cyclosporiasis, a parasitic infection that spreads via contaminated food or water, has hit more than 22,000 people across 45 states.

Linked to an iceberg lettuce farm in Mexico, it swept quickly through the US, killing two and leaving hundreds hospitalised over the past few weeks alone.

And health chiefs now warn the debilitating infection – which causes weeks of violent diarrhoea, abdominal cramps and vomiting – has reached the UK.

At least 67 Britons have fallen ill with cyclosporiasis since May. Officials are urging all travellers to take precautions when visiting or returning from North, Central and South America.

It may sound terrifying but experts say that, armed with the correct information, the parasite, called cyclospora, needn’t be a cause for concern.

‘It’s not something you want to get,’ says Dr Paul Hunter, microbiologist and professor of medicine at the University of East Anglia, ‘but there are clear ways to reduce your risk, on holiday or at home.’

What exactly is the cyclospora parasite?

Cyclospora is a single-cell organism, meaning, in layman’s terms, it is microscopically tiny.

It is a parasite that lives and multiples in the small intestine, burrowing into cells that line the gut wall. The frequent, watery diarrhoea associated with the bug is the body’s attempt to expel them.

Symptoms typically go on for a couple of weeks but can last up to a month, says Dr Lindsey Ann Edwards, senior lecturer in microbiology at King’s College London.

She adds: ‘The main sign is very watery diarrhoea over a prolonged period. While other bugs may clear up after a few days, cyclosporiasis continues.’

Some sufferers have described having to use the toilet up to 20 times a day, while others told of a bubbling, or balloon-like feeling in the stomach.

The parasite can also cause abdominal pain and nausea, but rarely vomiting.

Can I catch it from an infected person?

Cyclosporiasis differs from more common bugs in how it is spread. ‘The parasite can’t be passed on between humans, unlike many other diarrhoea-causing infections,’ says Professor Hunter.

In fact, people become infected with cyclospora only when they consume food or water that contains the parasite.

‘If you were just at dinner with, or even lived with, an infected person, you likely wouldn’t get it,’ says Professor Hunter.

Instead, outbreaks, such as the one in the US, occur when infected faecal matter comes into contact with crops, usually due to contaminated water supplies used to wash or grow produce.

Prof Hunter adds: ‘It’s raw vegetables and fruit – crops you won’t typically cook – that tend to spread cyclospora, as boiling can kill the parasite.

‘Salad leaves in particular are full of nooks and crannies and have a lot of surface area for the parasite to lay eggs on. And you don’t cook them – making them a perfect vehicle for cyclospora.’

Is it only salad I need to be worried about?

The US outbreak has been linked to Taylor’s Farm, a farm in Mexico that supplies bags of shredded lettuce to fast-food giant Taco Bell as well as grocery stores.

But previous outbreaks have been caused by a range of other fresh vegetables and fruit, including, most commonly, raspberries. ‘Anything that you eat without peeling or cooking could carry the parasite,’ says Professor Hunter.

Raspberries and blackberries have been behind a number of outbreaks for the same reason as salad leaves now are – they’re hard to clean well and full of little troughs and pits.

‘Vegetables with a waxy skin, like cucumbers, or that you typically peel – like oranges or carrots – are less likely to cause infections.’

How come it is now spreading to the UK?

Cyclospora is most prevalent in tropical regions such as South and Central America, Southeast Asia or the Middle East, as the parasite’s eggs can usually only survive in warm, humid conditions.

These regions typically also have poorer water treatment and sanitation infrastructure, making crop contamination more likely.

But while rare, there have been cyclospora outbreaks in the UK and Europe. Imported produce can bring in the infection, although most commonly people pick it up abroad, says Dr Edwards.

‘The parasite tends to incubate for around ten days, so people can go on a week-long holiday but then develop symptoms two or three days after getting back.

‘In the current outbreak, it seems most people have picked it up travelling to Mexico and the US.’

Will washing fruit and veg get rid of it?

‘It’s always a good idea to wash fresh fruit and vegetables,’ says Professor Hunter. ‘But with cyclospora, washing produce – while removing maybe 80 per cent of the parasites – won’t stop you getting sick, as the eggs, once laid, are difficult to dislodge.

‘Cooking is really the only way to kill off the bug.

‘I’ve always cautioned against eating uncooked vegetables – especially salads – when abroad.’

What’s the best way to treat an infection?

Once diagnosed via a stool sample, cyclosporiasis infections can be easily treated with antibiotics.

Trimethoprim-sulfamethoxazole, commonly sold as Bactrim, Septra or Cotrim, is taken twice daily for seven to ten days.

People with healthy immune systems can also usually get over the infection without treatment, but their symptoms can last up to a month and may relapse.

Hydration is key, says Dr Edwards, because of how much fluid is expelled. Sufferers should drink a lot of water, broths and take electrolytes and antibiotics.

Should I be worried about getting it?

Not unless you are planning an imminent trip to the US or Mexico.

If you are, at mealtimes or in restaurants, stick to cooked vegetables or ones that are peeled.

Those with a weakened immune system, as well as the elderly and children, should also be careful, adds Dr Edwards.

‘It’s not usually deadly – and given the number of infections in the US, two deaths makes sense statistically,’ she says.

‘But if you have underlying health conditions, it can make it much more difficult for your body to get rid of the parasite. Constant diarrhoea can cause severe dehydration, which can be deadly.’

Anyone returning from abroad who develops symptoms should seek help from their GP.