Trichomonas

Test code: X0013

Test name: Qualitative detection of Trichomonas by polymerase chain reaction

Many species in the genus Trichomonas can infect man, but trichomoniasis is also a major problem in poultry, birds and horses. All trichomonads have three to five anterior flagella, an undulating membrane, and a recurrent flagellum attached to the edge of the undulating membrane. There is no cyst stage for this protozoan parasite.

Following are some Trichomonads posing major health threats to humans, livestock, birds and other animals:

Trichomonas equi
This parasite lives in the intestine of horses and can be a potential cause of diarrhea in foals.

Trichomonas foetus/suis
T. foetus and T. suis are almost identical in genomic composition, morphologic structures, ultrastructure, distribution, host specificity, characteristics of in vitro cultivation, immunology and biochemistry (Lun et al., 2005). Thus, it has been proposed that T. foetus and T. suis are synonyms. While the parasite can be found in the nasal passage, stomach, colon and large intestine of swine, it does not appear to cause major health problems in them.

This trichomonad, however, causes trichomoniasis in cattle, resulting in significant economic loss. The parasite is sexually transmitted and resides in the reproductive tract of cattle. In females, the infection may result in low-grade inflammation, sterility and poor conception rate. In males, symptoms vary from no apparent signs to inflammation of the prepuce. Treatment is difficult and usually not attempted. Slaughter or breeding rest (females) are the usual methods employed in dealing with bovine trichomoniasis.

Like other trichomonads, this organism multiplies by simple binary fission and does not posses a cyst stage. This organism is also sometimes called Tritrichomonas foetus because it has three long flagella at one end.

Current diagnosis is mainly based on microscopic evaluation of the trophozoite stage. Mucus, exudates or saline washes from the vagina and preputial cavity are the best samples for microscopic examination. In cases of abortion, allantoic and amniotic fluids as well as fetal tissues and membranes are examined. Serologic detection by agglutination is now also available. However, none of these testing methods are highly sensitive, resulting in unacceptable false negative rates.

Trichomonas vaginalis
T. vaginalis causes human trichomoniasis. This parasite also resides in the human reproductive tract. This is one of the most common sexually transmitted diseases of man and often occurs with other more severe concurrent infections. Chronic reproductive and urinary problems may result in females. The parasite is transmitted sexually. Prevalence in human populations varies between 10 and 25% among women. Only about 15 % of infected women show clinical signs; many infected women are asymptomatic carriers.

Other trichomonads known to infect humans include Trichomonas tenax from the tarter and gums of the mouth and Pentatrichomonas hominis from the human colon.

Trichomonas gallinae
The parasite causes avian trichomoniasis. When present, it is usually found in the upper digestive tract of many species of doves and gallinaceous birds. Some strains may also produce liver and lung lesions. The parasite is transferred to young from the mother during feeding. Transmission between birds may also occur from contaminated feed and water. Infection by this trichomonad can be fatal. The presence of this organism in doves is a common source of infection of falcons and hawks feeding on them.

Trichomonas gallinarum
This parasite is mainly detected in cecum and liver of gallinaceous birds but it can also be found in other visceral organs of the infected animals. T. gallinarum affects many birds including poultry, and can cause morbidity and mortality especially in young birds.

Diagnosis of trichomoniasis may not be easy due to clinical symptoms which may resemble those of poxvirus, candidiasis or vitamin A deficiency. Trichomonas can be misidentified in initial microscopic examination because of its similarity to Giardia. The other difficulty in identification of this parasite is that the trichomonad does not survive long after the death of the host. Complementary testing by PCR may be used to eliminate false negative microscopy results. Molecular detection of this trichomonad by PCR does not require living parasites and provides a high degree of sensitivity and specificity.

Utilities:

• Confirm the disease causing agent
• Evironmental monitoring
• Ensure that herds are free of Trichomonas
• Early prevention of spread of this parasite
• Minimize human exposure to this parasite
• Safety monitoring of biological products that derive from horses

References:
Lun, Z.R., Chen, X.G., Zhu, X.Q., Li, X.R. and Xie, M.Q. (2005) Are Tritrichomonas foetus and Tritrichomonas suis synonyms? Trends Parasitol. 21:122-125.

Preferred specimens: Rectal, vaginal, oral or other mucous secretion swab, or 1 ml feces, shipped overnight at room temperature.

Less preferred specimens: 2 ml whole blood in EDTA (purple top) or ACD (yellow top) tube, or fresh, fixed or paraffin-embedded tissue shipped overnight at room temperature, or frozen tissue shipped frozen.

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: 2 business days

Methodology: Qualitative PCR

Normal range: Nondetected