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NOTE: A surveillance case definition is a set of uniform criteria used to define a disease for public health surveillance. Surveillance case definitions enable public health officials to classify and count cases consistently across reporting jurisdictions. Surveillance case definitions are not intended to be used by healthcare providers for making a clinical diagnosis or determining how to meet an individual patient’s health needs.

CSTE Position Statement(s)

  • 11-ID-14

Clinical Description

A gastrointestinal illness characterized by diarrhea and one or more of the following: diarrhea duration of 72 hours or more, abdominal cramping, vomiting, or anorexia.

Laboratory Criteria For Diagnosis

Confirmed: Evidence of Cryptosporidium organisms or DNA in stool, intestinal fluid, tissue samples, biopsy specimens, or other biological sample by certain laboratory methods with a high positive predictive value (PPV), e.g.,

  • Direct fluorescent antibody [DFA] test,
  • Polymerase chain reaction [PCR],
  • Enzyme immunoassay [EIA], OR
  • Light microscopy of stained specimen.

Probable: The detection of Cryptosporidium antigen by a screening test method, such as immunochromatographic card/rapid card test; or a laboratory test of unknown method.

Case Classification


  • A case with supportive laboratory test results for Cryptosporidia spp. infection using a method listed in the probable laboratory criteria. When the diagnostic test method on a laboratory test result for cryptosporidiosis cannot be determined, the case can only be classified as probable, OR
  • A case that meets the clinical criteria and is epidemiologically linked to a confirmed case.


A case that is diagnosed with Cryptosporidium spp. infection based on laboratory testing using a method listed in the confirmed criteria.


Persons who have a diarrheal illness and are epidemiologically linked to a probable case because that individual was only diagnosed with cryptosporidiosis by an immunocard/rapid test/ or unknown test method cannot be classified as probable cases. These epi-links can be considered suspect cases only.

Related Case Definition(s)