Cryptosporidiosis is protozoal infection causing a self-limited acute gastroenteritis characterized by nonbloody watery diarrhea.

  • Symptoms, when present, can also include abdominal pain, fever, fatigue, weight loss, vomiting, headache, and joint pain and typically last 1 to 2 weeks.
  • In an immunocompromised patient, gastrointestinal symptoms can be chronic, relapsing, and severe, causing profound and life-threatening wasting and malabsorption.
  • Extraintestinal: Pulmonary, biliary tract (sclerosing cholangitis, acalculous cholecystitis, pancreatitis), or disseminated infection rarely occurs among immunocompromised individuals.


  • Oocysts of Cryptosporidium are shed in the stool of infected hosts (humans, cattle, and other mammals) and are transmitted by fecal–oral contamination.
  • Disease is most commonly associated with contamination of water sources, both drinking and recreational, and transmission is also seen in association with child care centers or livestock.
  • Cryptosporidium has been found in all parts of the world and is a cause of traveler’s diarrhea.
  • Because of summer recreational water use, the incidence of cryptosporidiosis is highest in children and typically peaks in summer through early fall.


In the United States, an estimated 748,000 cases of cryptosporidiosis occur annually.

Risk Factors

  • Those most at risk for infection are children who attend child care centers, people who take care of others with cryptosporidiosis (including child care workers, parents of infected children, and health care workers), those who swim in or drink from contaminated water sources such as streams or unprotected wells, and people who handle livestock including those visiting petting zoos.
  • Because Cryptosporidium are chlorine tolerant, swimming in chlorinated pools does not decrease the risk of infection.

General Prevention

  • Drinking water should be adequately filtered to a particle size of 1 μm or smaller in order to ensure oocyst removal.
  • If a recreational water supply becomes contaminated, it should be closed, and proper decontamination measures should be implemented.
  • Those diagnosed with cryptosporidiosis should not swim for at least 2 weeks after diarrhea stops to help protect others.
  • Good hand hygiene, washing with soap and water vigorously for at least 20 seconds, is key after contact with animals or stool.
  • Children with diarrhea should not attend day care settings until diarrhea is resolved.
  • In day care settings, disinfection of diapering areas after each use and frequent disinfection of toys, tabletops, and highchairs during outbreaks is recommended.
  • Oocysts can survive for long periods and are resistant to many disinfectants including chlorine, iodine, and dilute bleach. Boiling water or full-strength bleach disinfectant is most effective.
  • Contact precautions are recommended for the length of the hospital stay for hospitalized patients.
  • Immunocompromised persons should avoid contact with any person or animal with cryptosporidiosis.


  • Transmission occurs via fecal–oral passage of oocysts from food, water, or poor hand hygiene.
  • The incubation period is typically 3 to 14 days with a median of 7 days, and oocyst shedding may occur for weeks to months after symptoms resolve. In the majority of people, shedding stops after 2 weeks. Immunocompromised patients can shed for several months.
  • Invasion of intestinal epithelial cells in the small intestine and proximal colon leads to a secretory diarrhea.
  • Intestinal destruction occurs with villous atrophy and subsequent malabsorption and increased intestinal permeability.

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