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Cryptosporidiosis (Cryptosporidium spp.)
1998 Case Definition

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