Disease caused by the Apicomplexan protozoan parasite Cryptosporidium .
Laboratory diagnosis is required, usually by detection of oocysts, antigens, or DNA in stool samples.
Presents as watery diarrhea, often with severe abdominal pain, commonly lasting >7 days.
The disease is self-limited in immunocompetent patients.
Patients who are severely immunocompromised may suffer chronic, severe, and intractable disease. Most at risk are those with T-cell immune deficiencies, notably advanced HIV infection, or primary T-cell immune deficiencies, and those with hematologic malignancies, particularly children.
Nitazoxanide may be used for treatment of cryptosporidiosis in immunocompetent people >1 year of age.
Cryptosporidium has caused outbreaks associated with, for example, contaminated drinking water supplies, food (especially fresh produce), swimming pools, children's day care facilities, and petting farms.
Cryptosporidiosis is illness caused by the protozoan parasite Cryptosporidium , characterized by watery diarrhea and often accompanied by abdominal cramps, loss of appetite, low-grade fever, nausea, and/or vomiting. Symptoms, which usually last for up to 2 weeks and sometimes up to 4 weeks, may relapse after initial resolution. Cryptosporidium can cause prolonged, severe disease that may be life-threatening in some groups of severely immunocompromised patients.  
Consultant Clinical Scientist/Honorary Professor
Director of UK Cryptosporidium Reference Unit
Public Health Wales Microbiology
RMC has been involved with the following boards: WHO Water Quality and Health Technical Advisory Group; Europe ISO/TC34/SC9/WG6 “Methods for Cyptosporidium and Giardia in food”; Public Health England Gastro-Intestinal Programme Board; Wales Microbiology Standing Specialist Advisory Group. RMC’s institution has received payments for grants and contract research. RMC has received payments for lectures to Environmental Health Officers and royalties for the Elsevier for Microbiology of Waterborne Diseases book. RMC is an author of a number of references cited in this monograph.
Clinical Associate Professor
College of Medicine
APD is an author of a number of references cited in this monograph.
University of Vermont College of Medicine
BK declares that she has no competing interests.
Stanford Health Promotion Network
Stanford School of Medicine
YM declares that he has no competing interests.
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