Cryptosporidium

Cryptosporidium, often referred to as "crypto," is a tiny parasite that can live in the intestines of humans and animals. The parasite is protected by an outer shell that allows it to survive outside the body for long periods of time and makes it very resistant to chlorine disinfection.

Cryptosporidium may be spread by:

Accidentally swallowing anything that has come in contact with the stool of a person or animal
Swallowing contaminated water from swimming pools, hot tubs, lakes, rivers, springs, ponds, or streams contaminated with sewage or feces from humans or animals.
Eating uncooked contaminated food.
Picking cryptosporidium up from surfaces contaminated with stool from an infected person (such as toys, bathroom fixtures, changing tables, and diaper pails).

The CDC recommends:

Your child should wash their hands with soap and water after using the toilet, changing diapers, and before eating or helping prepare food.
Avoid water or food that may be contaminated.
Washing and/or peeling all raw vegetables and fruits before giving them to your child to eat.
Avoiding drinking water from lakes, rivers, springs, ponds, or streams unless it has been filtered and chemically treated.
Boiling drinking water for one minute to kill the Giardia parasite. This will ensure safe drinking water during community-wide outbreaks caused by contaminated drinking water.
When camping or traveling in countries where the water supply may be unsafe, avoid drinking unboiled tap water and avoid uncooked foods washed with unboiled tap water.
Avoiding swimming in pools if your child has had cryptosporidium and for at least two weeks after diarrhea stops. Crypto can be passed in the stool and contaminate water for several weeks after your child no longer has symptoms. This has resulted in several outbreaks of cryptosporidium among pool users. Crypto can survive in chlorinated pools for several days.