wildlife, zoo and aquatic assay data sheet

Pseudocapillaria tomentosa

Test code: X0026 - Ultrasensitive qualitative detection of Pseudocapillaria tomentosa by real time PCR

Infection of captive fishes by metazoan parasites (helminths and arthropods) is of major concern in fish farms and in research facilities. Water systems in these facilities usually must use unchlorinated water, creating a risk of the growth of unwanted organisms.

Metazoan parasites which require intermediate hosts in their cycles are not common in these facilities. However, capillarid nematodes do not require intermediate hosts and thus are one of the few metazoans that are of concern. They are recognized as a major problem in zebrafish facilities particularly (Kent et al., 2002).

The species infecting zebrafish was first identified as Pseudocapillaria tomentosa; the junior synonym is P. brevispicula. The parasite has a broad host specificity, infecting some 25 fishes in the family Cyprinidae and members of other orders such as Aguilliformes (eels), Gadiformes (cod fishes), Salmoniformes (salmon) and Siluriformes (catfishes).

Fish heavily infected with this parasite are often dark, emaciated, and lethargic. Necropsy may reveal liver enlargement and anemia. Slightly infected fish can appear normal or may show only subtle abnormalities such as decreased fecundity.

Adult worms may be found in the intestine of infected fish upon necropsy. Characteristic ova (~30 x 60 µm) may be seen within gravid female worms or found free within the intestinal contents or feces. Histological examinations of the gut may reveal the worms within the lumen or wall of the intestine.

Nematode infection in zebrafish is difficult to eliminate. Sometimes the entire colony may have to be destroyed and the water system completely disinfected. Since direct transmission can occur between fish, the infection can spread within a population easily. The use of strict quarantine procedures that allow only the introduction of surface sanitized (bleached) embryos may help minimize infections. Oligochaete (eg Tubifex) worms can also carry the parasite and thus should be avoided as a food source. Routine monitoring of a water system, especially filters where ova may be concentrated, is helpful. Molecular detection of these ova by polymerase chain reaction (PCR) is highly sensitive and is easily used to perform this monitoring.

Utilities:

• Help confirm the disease causing agent
• Shorten the time required to confirm a clinical diagnosis of P. tomentosa infection
• Routine monitoring of aquaculture and zebrafish research facility water systems
• Early prevention of spread of P. tomentosa between fish or through a water system
• Minimize human exposure to P. tomentosa

References:
Kent, M. L., Bishop-Stewart, J. K., Matthews, J. L., and Spitsbergen, J. M. (2002). Pseudocapillaria tomentosa, a nematode pathogen, and associated neoplasm of zebrafish (Danio rerio) kept in research colonies. Comp. Med. 52, 354-358.

Specimen requirement: 0.2 ml feces or intestinal contents, or vent swab, or 0.2 ml tissue, or swab of filter medium, or biofilm swab.

Contact Zoologix if advice is needed to determine an appropriate specimen type for a specific diagnostic application. For specimen types not listed here, please contact Zoologix 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: 2 business days

Methodology: Qualitative real time PCR

Normal range: Nondetected