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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

  • Demonstration of Cryptosporidium oocysts in stool, OR
  • Demonstration of Cryptosporidium in intestinal fluid or small-bowel biopsy specimens, OR
  • Demonstration of Cryptosporidium antigen in stool by a specific immunodiagnostic test (e.g., enzyme-linked immunosorbent assay)

Case Classification


A clinically compatible case that is epidemiologically linked to a confirmed case


A case that is laboratory confirmed


The 1995 case definition appearing on this page was re-published in the 1997 MMWR Recommendations and Reports titled Case Definitions for Infectious Conditions Under Public Health Surveillance.1 Thus, the 1995 and 1997 versions of this case definition are identical.


  1. CDC. (1997). Case Definitions for Infectious Conditions Under Public Health Surveillance. MMWR, 46(RR-10), 1-55.

Related Case Definition(s)