The Place Where Movies Never Get Old

Outbreaks of Cryptosporidium (Crypto) in the United States increased an average 13% each year from 2009-2017, according to a report published in CDC’s Morbidity and Mortality Weekly Report.

Crypto, a parasite, is spread through the poop of infected humans or animals. People can get sick after they swallow the parasite in contaminated water or food or after contact with infected people or animals. Crypto is the leading cause of disease outbreaks in the United States linked to water, specifically outbreaks linked to pools or water playgrounds.

Hundreds of outbreaks caused by Crypto

The report describes 444 outbreaks reported from 2009 through 2017, resulting in 7,465 people becoming sick, 287 hospitalizations, and one death.

  • 35% of the outbreaks were linked to treated swimming water in places like pools and water playgrounds.
  • 15% were linked to contact with cattle, particularly calves who were still nursing.
  • 13% were linked to contact with infected people in childcare settings.
  • 3% were linked to drinking raw (unpasteurized) milk or apple cider.

Improvements in testing patients for Crypto in recent years might be contributing to increased detection of outbreaks.


Michele Hlavsa, R.N., M.P.H., chief of CDC’s Healthy Swimming Program

“Young children can get seriously sick and easily spread Crypto. They don’t know how to use the toilet and wash their hands, or are just learning how. But we as parents can take steps to help keep our kids healthy in the water, around animals, and in childcare.”

Crypto is a challenging parasite

Crypto is protected by an outer shell that makes it tough to kill. For example, it can survive for days in chlorinated water in pools and water playgrounds or on surfaces disinfected with chlorine bleach. Crypto can easily cause outbreaks because it only takes a few germs to make someone sick, and there can be millions of Crypto germs in poop. Someone sick with Crypto can have diarrhea for up to three weeks.

Protect yourself and family from getting sick

Outbreaks caused by Crypto occur most commonly in the summer. Follow these effective steps to protect yourself and others this summer and year-round:

  • Do not swim or let kids swim if they have diarrhea.
    • If diagnosed with cryptosporidiosis, do not swim until two weeks after diarrhea completely stops.
  • Do not swallow the water you swim in.
  • Keep kids sick with diarrhea at home and away from childcare.
  • Wash your hands with soap and water after coming in contact with animals or anything in their environment, especially animal poop. Alcohol-based hand sanitizers do not work effectively on Crypto.
  • Remove shoes worn in the animal environments (for example, in barns) before going inside your home.
  • If you drink milk or apple cider, only buy if it has been pasteurized.