National case definition: Cryptosporidiosis

Date of last revision/review: December 2023.

National notification

Only confirmed cases of disease should be notified.

Type of surveillance

Routine case-by-case notification to the federal level.

Case classification

Confirmed case

Laboratory confirmation of infection with or without clinical illness from an appropriate clinical specimen (e.g., stool, intestinal fluid, small bowel biopsy), with demonstration of:

• Cryptosporidium spp. oocysts;
  or
• Cryptosporidium spp. nucleic acid (e.g., by polymerase chain reaction (PCR) or other nucleic acid test (NAT));
  or
• Cryptosporidium spp. antigen (e.g., by an immunologic assay).

Probable case

Clinical illness in a person who is epidemiologically linked to a confirmed case.

Laboratory comments

While Cryptosporidium parvum and Cryptosporidium hominis are the leading causes of cryptosporidiosis, other species are known to cause diarrheal illness in immunocompromised individuals.

Untreated and unfixed (i.e., without formalin) clinical specimens are recommended for PCR and deoxyribonucleic acid (DNA) based methodologies including molecular diagnostic testing and downstream molecular surveillance approaches. Formalin-based fixatives used for microscopy can interfere with nucleic acid detection and sequencing.

Note: For molecular surveillance purposes, Cary Blair transport media is acceptable.

Clinical evidence

Clinical illness may be characterized by the following signs or symptoms: Diarrhea (often profuse and watery), abdominal pain, anorexia, fever, nausea, general malaise, dehydration, and/or vomiting. The severity of illness may vary. While not considered clinical illness, asymptomatic infections may occur.

ICD code(s)

ICD-11 code(s)

• 1A32 Cryptosporidiosis

ICD-10 code(s)

• A07.2 Cryptosporidiosis

Comments

Probable case definitions are provided as guidelines to assist with case finding and public health management, and are not for national notification purposes.