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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.

Clinical Description

An illness caused by the protozoan Cryptosporidium parvum and characterized by diarrhea, abdominal cramps, loss of appetite, low-grade fever, nausea, and vomiting. Infected persons may be asymptomatic. The disease can be prolonged and life-threatening in severely immunocompromised persons.

Laboratory Criteria For Diagnosis

Laboratory-confirmed cryptosporidiosis shall be defined as the detection—in symptomatic or asymptomatic persons—of Cryptosporidium

  • Oocysts in stool by microscopic examination, OR
  • In intestinal fluid or small-bowel biopsy specimens, OR
  • Oocyst or sporozoite antigens by immunodiagnostic methods, e.g., enzyme-linked immunosorbent assay (ELISA), OR
  • By polymerase chain reaction (PCR) techniques when routinely available, OR
  • Demonstration of reproductive stages in tissue preparations.

Case Classification


Confirmed, symptomatic: a laboratory-confirmed case associated with one of the symptoms described above
Confirmed, asymptomatic: a laboratory-confirmed case associated with none of the above symptoms

Related Case Definition(s)