Cryptosporidium – commonly referred to as just ‘Crypto’ – is a microscopic parasite that lives naturally inside of animals. It is very common to find Crypto in lakes and ponds in the countryside, where it passes through and is deposited into the water via animal waste.

Crypto’s ubiquity means it also frequently makes its way into reservoirs and other water supplies. It has a nasty tendency to appear in swimming pools; especially during the summer holidays.

What’s disturbing about this parasite is that it seems to have evolved a defence mechanism to resist cleaning agents. For example, Crypto has a protective “shell” that even chlorine is unable to breakdown. Once it contaminates a water supply, infection can spread quickly. In 2016, more than 223 people in Devon and Dorset fell ill to an outbreak that stemmed from a contaminated swimming pool, causing illness, diarrhoea and other misery.

Most symptoms are aggressive — vomiting, diarrhoea and fever — but relatively short lived. But in immunocompromised people, Crypto can actually be fatal.

Given the extent that Crypto can be found throughout the natural world, and especially in the UK, the parasite’s reputation is perhaps underrated. Mention the term to a friend or family member, and it is highly unlikely they will even have heard of it. No wonder cases of the parasite is increasing.

With this in mind, what can actually be done to avoid catching the Crypto bug?