Cryptosporidium is spread by ingesting the parasite from contaminated food, fluids or surfaces. When you are travelling, particularly on cruise ships, where many people use the same facilities, cryptosporidium would be easily spread if an infected person isn’t careful about their hygiene. An infected person can shed millions of parasites in their faeces, and these can make their way into food and swimming pools if not careful.
It can also be contracted after touching your mouth with your hand if it has come into contact with a contaminated object or surface (for example, nappies from an infected infant, or while caring for an infected person). So if you or your travel companions are unwell, it is best to avoid others as much as possible. Even if you are not on a boat, cryptosporidium can be a threat for adventurous travellers who might consider drinking from lakes or streams. Beware - animals can also contract cryptosporidium and contaminate lakes and other untreated water sources.