By early September 2005, over 3,800 people reported symptoms of a Cryptosporidium infection. The "Sprayground" was ordered closed for the season on 15 August. In October 2005, the Gwynedd and Anglesey areas of North Wales, the United Kingdom, suffered an outbreak of cryptosporidiosis. The outbreak may have been linked to the drinking water supply from Llyn Cwellyn, but this is not yet confirmed. As a result, 231 people fell ill and the company Welsh Water (Dwr Cymru) advised 61,000 people to boil their water before use. In March 2007, a suspected outbreak occurred in Galway, Ireland, after the source of water for much of the county, Lough Corrib, was suspected to be contaminated with the parasite. A large population (90,000 people), including areas of both Galway City and County, were advised to boil water for drinking, food preparation and for brushing teeth. On 21 March 2007, it was confirmed that the city and countys water supply was contaminated with the parasite. The areas water supply was finally given approval on 20 August 2007, five months after Cryptosporidium was first detected. Around 240 people are known to have contracted the disease; experts say the true figure could be up to 5,000. Hundreds of public pools in 20 Utah counties were closed to young children in 2007, as children under 5 are most likely to spread the disease, especially children wearing diapers.
In addition, people should refrain from engaging in sexual activities that can expose them to feces.Standard water filtration may not be enough to eliminate Cryptosporidium; boiling for at least 1 minute (3 minutes above 6,500 feet (2,000 m) of altitude) will decontaminate it. Heating milk at 71.7 °C (161 °F) for 15 seconds pasteurizes it and can destroy the oocysts ability to infect. Water can also be made safe by filtering with a filter with pore size not greater than 1 micrometre, or by filters that have been approved for "cyst removal" by NSF International National Sanitation Foundation. Bottled drinking water is less likely to contain Cryptosporidium, especially if the water is from an underground source.People with cryptosporidiosis should not swim in communal areas because the pathogen can reside in the anal and genital areas and be washed off. They should wait until at least two weeks after diarrhea stops before entering public water sources, since oocysts can still be shed for a while. Also, they should stay away from immunosuppressed people. Immunocompromised people should take care to protect themselves from water in lakes and streams. They should also stay away from animal stools and wash their hands after touching animals. To be safe, they should boil or filter their water.