Cryptosporidium

Test codes:

P0008 - Ultrasensitive qualitative screen for Cryptosporidium by nested polymerase chain reaction. This screen detects but does not differentiate Cryptosporidium species.

P0009 - Ultrasensitive qualitative identification of Cryptosporidium species by nested polymerase chain reaction and restriction fragment length polymorphism (RFLP).

Several of the 13+ species in the Cryptosporidium genus have been confirmed as causative agents of human disease. Cryptosporidium is a parasitic protozoan that is transmitted by multiple routes; the animal host range is diverse. The following Cryptosporidium species are currently accepted, on the basis of host specificity, pathogenesis, morphology and genotyping:

Infecting mammals: Cryptosporidium hominis, C. parvum, C. wrairi, C. felis, C. canis, C. andersoni and C. muris

Infecting birds: C. baileyi, C. meleagridis and C. galli

Infecting reptiles: C. serpentis and C. saurophilum

Infecting fish: C. molnari

Phylogenetic analyses have been largely based on sequencing of the small subunit rRNA gene (18S rRNA), the hsp 70 gene, or other housekeeping or structural genes. These analyses reveal that the various Cryptosporidium species interact in complex ways with hosts. For example, the specific host of C. felis is cats, but this species has also been isolated from a cow, while C. andersoni is morphologically close to C. muris but infects cattle rather than mice. And C. parvum includes a complex of subspecies that specifically infect cattle, pigs, kangaroos, ferrets or monkeys.

With the advance of molecular techniques, knowledge of the epidemiology of human cryptosporidiosis has significantly increased. It has been shown that the vast majority of human cases are caused by C. hominis (synonymous with C. parvum genotype 1) and C. parvum (synonymous with C. parvum genotype 2). Other species, including C. meleagridis, C. felis, C. canis and C. muris can also infect humans and are linked to clinical disease, not only in immunocompromised patients but also in immunocompetent people.

Although traditional microscopy and staining methods are commonly used for the primary diagnosis of cryptosporidiosis, they are often inadequate to discriminate among many of the species of Cryptosporidium. Similarly, antibody-based tests such as enzyme linked immunosorbent assays (ELISA) and immunofluorescent microscopy, which are used in other health-care settings and in water testing laboratories, are also incapable of offering such differentiation (Thomas and Chalmers, 2003). PCR is a rapid and extremely sensitive technique for detection of Cryptosporidium. Further analysis by Restriction Fragment Length Polymorphism (RFLP) assay allows differentiation of many Cryptosporidium species.

Utilities:

• Confirm the disease causing agent
• Shorten the time required to confirm a clinical diagnosis of Cryptosporidium infection.
• Ensure that animal groups and facilities are free of Cryptosporidium
• Early prevention of spread of this protozoan
• Minimize human exposure to this protozoan

References:
Thomas, A.L. and Chalmers, R.M. (2003) Investigation of the range of Cryptosporidium species detected by commercially available antibody-based tests. Proceedings of the Health Protection Agency Inaugural Conference, Warwick, September.

Specimen requirements: 0.5 ml feces, or rectal swab.

For specimen types other than those listed here, please call to confirm specimen acceptability and shipping instructions.

For all specimen types, if there will be a delay in shipping, or during very warm weather, refrigerate specimens until shipped and ship with a cold pack unless more stringent shipping requirements are specified. Frozen specimens should be shipped so as to remain frozen in transit. See shipping instructions for more information

Turnaround time:
P0008 - 2 business days
P0009 - 3 business days

Methodologies:
P0008 - Qualitative nested PCR
P0009 - Qualitative nested PCR and RFLP

Normal range: Nondetected