Tritrichomonas fetus - Microscopic exam and molecular diagnosis (PCR)


Tritrichomonas fetus is a flagellate single - celled protozoan of the genus Trichomonas, family Trichomonadidae, Phytomastigophorea class and phylum Sarcomastigophora, with a worldwide distribution. This parasite mainly affects cattle and cats, which causes Trichomonosis (tritrichomonosis) and bovine Trichomonosis (tritrichomonosis) cat, respectively. Trichomonosis bovine disease is considered a reproduction of prevalent sexually transmitted (venereal) and economically important cause of infertility and abortion in cattle reared naturally. In cats, it is considered a cause of chronic diarrhea colonic. It has been observed in pigs, but the effect it can have on them is unknown.

Tritrichomonas fetus is an organism piriform 10 to 25 .mu.m to 15 .mu.m x 3, although due to the plasticity of their protoplasm takes various forms. This microorganism has a usually spherical or ovoid nucleus. They have identified two forms of Tritrichomonas fetus: one in the trophozoite stage characterized by an elongated shape, and other cyst - oval and immobile form, which appears in unfavorable environmental conditions such as temperature hostile or nutritional deficiencies. Furthermore, Tritrichomonas fetus has three anterior flagella of 11 to 17 .mu.m and a rear scourge of 16 .mu.m. The characteristics of pyriform shape or elongated, and the number and arrangement of flagella are those that are considered to differentiate it from other flagellated protozoa as pathogens not Pentatrichomonas or Tetratrichomonas.

The life cycle of this organism involves only a host where it multiplies and mature. The route of transmission, the process of infection and the signs and symptoms associated Tritrichomonas fetus infection vary according to the affected animal.

In cattle, the transmission of Tritrichomonas fetus occurs mainly through sexual contact because this protozoan is in the preputial epithelium of the penis steers and bulls, which persists throughout life for what is considered the reservoir this agent and the reason to be sacrificed when the infection is detected. During intercourse it is transmitted to females in which invades the vagina, uterus and oviduct, causing infertility for a period of 2 to 6 months as heifers and cows recover from the infection. Occasionally, the transmission can also occur during the practice of artificial insemination or vaginal examination if contaminated material is used. Vagina invasion induces a mild inflammatory response characterized by proliferation of lymphocytes, macrophages and plasma cells in the lamina propria vaginal persisting in the genital secretions. During pregnancy invade the placenta and fetus killing embryos. Trophozoites multiply asexually by binary fission. In the male, the infection is asymptomatic, but persists so that infected animals are detected are usually slaughtered. Heifers or cows in the infection by this organism can cause infertility as well as endometritis, cervicitis, salpingitis and placentitis. As a result, fetus infection causes abortions Tritrichomonas in the embryonic and fetal periods before day 120 of gestation. In the first two months of gestation, the agent is able to penetrate the placenta and chorion epithelium fetal colonizing mucosal adjacent connective tissues and lymph. It is believed that the parasite is sucked by the fetus from the amniotic fluid, resulting in colonization of stomach, intestine and fetal lungs. Cases of infection in cattle have been reduced through the use of artificial insemination. The prevalence of infection varies from one region to another. In the western US It is estimated that the prevalence of infection is 5 to 8% in a California study found a prevalence rate of 16 and others 27%; a Nevada ranch 46% was found. In areas where cattle breeding is done by artificial insemination controlling breeding animals, this infection has been controlled, as in Central Europe. And in Switzerland until 1994 he had not been a case in 20 years, and in the UK, only two cases in the same period. In the Northwest of Spain the prevalence was 2.9% in natural breeding herds.

In cats, Tritrichomonas fetus transmission occurs by direct contact, mainly when they are crowded. The parasite is spread orally (faecal-oral). Once inside the body of the animal, Tritrichomonas fetus colonizes the mucosa of ileum, caecum and colon in small and mobile trophozoites, which have the ability to adhere to the intestinal epithelium, where it reproduces asexually by binary fission, causing chronic diarrhea box. The infected cat eliminates the parasite in their feces, infecting other cats to have contact with them. Tritrichomonas fetus infection presents with intermittent diarrhea that may contain blood and mucus sometimes. In most cases it affects young cats aged 12 months or less and cats in shelters are overcrowded shelters and homes where several cats live. Tritrichomonas fetus mainly causes diarrhea by colonization of the large intestine (Colonic chronic diarrhea). Recovery is slow, but generally the long - term prognosis is good. However, cats that have recovered and show no clinical signs can continue to remove the body with feces for about two years.

Recommended tests for diagnosis:


The diagnosis is based on three methods: microscopic examination, cultivation in suitable media and molecular diagnosis (PCR).

For microscopic examination with light microscopy, they are used scrapings or washing foreskin steer or bulls, or cervico-vaginal secretion of heifers or cows. Microscopic examination is to demonstrate the presence of organisms piriform or elongated morphology, staining phones that show the three previous flagella and subsequent scourge. Although other flagellate species are larger and rounded, these differences are not appreciated in light microscopy sometimes, so that false positive results can occur, which may lead to unjustified slaughter of animals. In cats it is done l microscopic examination of feces diluted in saline. To facilitate viewing, the stool must be newly issued (fresh), and diarrheal consistency. The cooling causes the death of the organism, which does give false negative results, to be hindered their finding.

The culture is recommended when the number of parasites is low, to facilitate diagnosis, increasing diagnostic sensitivity, regarding the direct microscopic observation of samples 10 to 48%. For this purpose various culture media may be used, such as Diamond 's medium or half TF. The problem is that a cultivation period of 2 to 7 days is required, with daily monitoring of crops. Despite the cultivation, only it detected 80 to 90% of infected males and 60 to 80% of infected females.

For the above reasons, nowadays, the molecular diagnostic methods (PCR) are replacing conventional methods of microscopic observation and culture, since it facilitates its detection through the discovery of DNA, and also avoids confused with the presence of other flagellate protozoa, as may occur with the microscopic observation and finding Pentatrichomonas or Tetratrichomonas.

Tests in IVAMI:


  • Microscopic examination.
  • Molecular diagnosis (PCR), to detect DNA Trichomonas fetus.

Recommended sample:


  • In cattle: scraping or preputial steers and bulls; cervico-vaginal heifers or cows. Secretion
  • In cats: fresh faeces, newly issued and diarrhea.


Preservation and shipment of sample:


  • Refrigerated (preferred) for less than 2 days (for molecular diagnostics).
  • Frozen: over 2 days (for molecular diagnostic tests only).


Delivery term:


  • Microscopic examination: less than 24 hours.
  • Molecular diagnosis (PCR): 24 to 48 hours.

Cost of the test: