Trypanosoma equiperdum ("Dourine") NOTE: THIS TEST IS NOT PERFORMED ON SAMPLES TAKEN FROM ANIMALS OWNED OR LOCATED IN THE STATE OF CALIFORNIA.

Test code: X0018 - Ultrasensitive qualitative detection of Trypanosoma equiperdum, the etiologic agent of Dourine or "Covering Sickness," by real time polymerase chain reaction

Trypanosoma equiperdum is a protozoan that causes Dourine, or Covering Sickness, in horses and other equines such as donkeys and mules. Horses are most susceptible, donkeys much less so. Unlike other species of Trypanosome, this parasite can be sexually transmitted, and does not require a vector. However, spread of the disease has been documented as far north as Canada and Russia, and as far south as Chile and South Africa. The disease has been eradicated from many parts of the world, mainly by repeated clinical testing and slaughter of positive animals.

Variable symptoms can result from infection with this protozoan. Classically, there are three stages. During the first stage, the genitalia become swollen and in mares there is a discharge from the vagina.  Often a patchy loss of pigment in the mucosa of the vulva or penis is observed. Slight fever and a loss of appetite may be noticeable. After four weeks or so, the second stage begins, with round urticarial areas on the neck, the chest, the flanks and the rump. The appearance of these plaques has been described as “a coin inserted under the skin”. They are visible for a few days before disappearing, but may come back. In the third stage, a paralysis sets in, involving various muscles, and spreading to the hind legs, causing loss of coordination. Complete paralysis of all four legs may finally occur.

However, these classical symptoms may not occur with the infection. Many infected animals, especially in long-standing endemic regions, develop symptoms that are rather mild without any apparent stages. There also appear to be differences in virulence between strains. Even in cases terminating fatally, the disease may last for a year or even two years.

Diagnosis of dourine can be difficult. Classical symptoms, if present, can be of great help in an area where the disease is known to occur. Trypanosomes are not normally found in the circulating blood, but may be detectable in fresh preparations or stained smears of discharge from the vagina or tissue fluid taken from the swollen genitalia or the urticarial plaques. Traditionally, the complement fixation test has been used to identify carriers. Although the complement fixation test is still mandatory in some countries, modern, more sensitive tests are now preferable, eg IFA or ELISA. Nevertheless, none of these serological methods can differentiate between T. equiperdum and other trypanosomes, such as T. evansi and T. brucei. Molecular detection of T. equiperdum by PCR is not only rapid and highly sensitive, but is also able to differentiate it from other Trypanosomes (Zablotskij et al., 2003).

Utilities:

• Help confirm the disease causing agent
• Shorten the time required to confirm a clinical diagnosis of T. equiperdum infection.
• Help ensure that animal herds and populations are free of T. equiperdum
• Early prevention of spread of this parasite among a herd
• Minimize personnel exposure to this parasite
• Safety monitoring of biological products and vaccines that derive from equines

References:
Zablotskij, V.T., Georgiu, C., de Waal, T., Clausen, P.H., Claes, F. and Touratier, L. (2003) The current challenges of dourine: difficulties in differentiating Trypanosoma equiperdum within the subgenus Trypanozoon. Rev.  Sci. Tech.22:1087-96.

Specimen requirement: 0.2 ml urine, or urogenital or vaginal 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