Tritrichomonas foetus

Tritrichomonas foetus
Tritrichomonas foetus

Tritrichomonas foetus is a single celled flagellated protozoan parasite that is known to be a pathogen of the bovine reproductive tract as well as the intestinal tract of cats. In cattle, the organism is transmitted to the female vagina and uterus from the foreskin of the bull where the parasite is known to reside. It causes infertility, and, at times, has caused spontaneous abortions in the first trimester. Cases of infection in cattle have declined due to the use of artificial insemination. In the last ten years, there have been reports of Tritrichomonas foetus in the feces of young cats that have diarrhea[1] and live in households with multiple cats.

Description

Tritrichomonas foetus in the genus Tritrichomonas within the order Trichomonadida in the Kingdom Protoctista. The parasite is 5-25 µm in size and is spindle shaped with four flagella which are whiplike projections and an undulating or wavy membrane. Their movement is jerky and in a forward direction, and they also do "barrel rolls". The organisms look like small tadpoles with small tails when viewed microscopically. The parasite interacts with bacteria that normally reside in the intestinal tract by adhering to the intestinal epithelium of the host.

Clinical signs

Bulls do not show any clinical signs of infections and can infect females at mating. In cows, there may be infertility, embryonic death and abortion, and reproductive tract infections such as pyometra.[2][3] Cows may show outward signs of infection, namely a sticky, white vaginal discharge, which may occur for up to two months after the initial infection. The disease results in abortion of the embryo, often within ten days of conception. Evidence of repeat breeding or infertility may be a sign of trichomoniasis. After the abortion of the fetus and the cow's return to a normal menstrual cycle, the cow may come into estrus again, at which point it may be bred again. Eventually the cow will be able to cycle normally and carry a fetus to term. However, the irregularities after initial infection present obvious clinical signs of reproductive inconsistencies, which should be examined by a veterinarian immediately.[4]

In cats, Tritrichomonas foetus is characterized by diarrhea that comes and goes and may contain blood and mucus at times. The diarrhea is semi formed in a cow pie consistency. In most cases it affects cats of 12 months of age or younger and cats from rescue shelters and homes with multiple cats. Close and direct contact appears to be the mode in which the parasite is transmitted. Tritrichomonas foetus is most common in purebred felines, breeds like Bengals, Persians, etc. Since catteries tend to trade queens and studs to provide greater genetic diversity, the parasite can be spread from one cattery to another.

Diagnosis

In cattle, a presumptive diagnosis can be made from the signs of infertility and geography. Diagnosis may rely on microscopic examination of vaginal or preputial smears. Complement fixation can be performed to detect parasite antibodies in vaginal secretions.[3] Although diagnosis can be achieved via microscopy and cultivation of the protozoan, these diagnostic methods are not always accurate. Several related trichomonads may be mistaken for Tritrichomonas foetus, including: Trichomonas vaginalis, Trichomonas gallinae, and Trichomonas tenax. A study by Richard Felleisen found that identification of T. foetus using Polymerase chain reaction (PCR) resulted in a more accurate identification. The 5.8S rRNA gene of T. foetus was found to have 12 copies in the T. foetus genome. This indicated that the organism could be identified via amplification of this gene by PCR. Not only would this allow for identification of T. foetus, but also differentiation from other trichomonad species.[4] Diagnosis can also done using the InPouch TF, as described below. The only difference between using this method on cattle and cats is that a sample is acquired via scraping the glans penis and prepuce of a bull with a sterile syringe.

In cats, Tritrichomonas foetus can be detected by two methods:

  1. InPouch TF - a culture pouch available from BioMed Disgnostics.[5] The pouch is loaded with a small amount of fecal specimen. The culture pouch may be kept at room temperature, but faster results may be obtained if kept at 80-90 °F. Results can be expected within 2 weeks by examining the clear pouch under a microscope (100x-300x magnification) for the T. foetus organism. The InPouch TF culture kit is very inexpensive and easy to prepare.
  2. PCR testing - A fecal sample is sent to a diagnostic laboratory for analysis. PCR testing searches the specimen for genetic evidence of the T. foetus organism. This test is the most reliable available at this time. The PCR test takes just a few days to complete, so it is the fastest way to get results.

Treatment

Treatment of the infection is difficult due to drug resistance. Traditional antiprotozoal drugs such as fenbendazole and metronidazole do not alleviate the symptoms. Some antimicrobial drugs have been shown to improve symptoms but do not eradicate the parasite.

Dr. Jody Gookin at North Carolina State University, College of Veterinary Medicine, has published research on the effectiveness of the drug ronidazole.[6] Currently there is no drug specifically indicated for T. foetus in felines, and ronidazole treatment is considered an off-label use. Ronidazole has had good efficacy in eradiation of the parasite in felines. Care should be used when administering the drug. Exact dosing is essential, and caplets are recommended over suspension to increase dose accuracy. Additionally, ronidazole has the potential for a variety of side effects, most importantly, neurological side effects. During treatment, the cat should be engaged in play activity regularly to ensure they are not experiencing neurological side effects, or motor skills impairment. Two weeks of ronidazole, 30 mg/kg, once daily, is currently the recommended dosage. Care should be exercised while handling ronidazole, which is thought to be a mutagen and carcinogen to humans when handled over a long period.[7]

In cattle, bulls can receive topical treatment with acriflavine. Bulls must be culled if treatment is ineffective. Bulls that have acquired the disease remain carriers for life. This presents a major dilemma, due to the lack of clinical symptoms of infection in bulls. Cows on the other hand can be vaccinated against the parasite. Vaccinations must be administered at 8 weeks and 4 weeks prior to breeding. Artificial insemination has been shown to drastically reduce the venereal transmission and prevalence of the disease.[3] If artificial insemination is not affordable or otherwise unavailable, virgin bulls should be utilized. Virgin bulls have no contact with the disease, due to the necessary sexual transmission.[8]

During treatment, the feline should be keep isolated from other cats as to prevent the spread to another cat (typically transmitted by an infected cat sharing the same litter box as other cats). The cat should be fed a veterinarian prescribed dry-food diet, preferably of high fiber content. Wet food should be avoided. A common GI diet remedy in cats (boiled chicken breast, white rice, and pumpkin) may be highly beneficial during and after treatment. Berenil can be applied on the prepuce of Bull.

Prognosis

The prognosis for cattle is not that great. Infected bulls must be culled, as should infected cows. Trichomoniasis is a reportable disease in cattle, and as of now, there is no legal treatment. Prevention and smart farm practices are the only remedy. Testing should be done on any bull prior to exposing it to the herd. Limiting exposure of the herd to other cattle and limiting the introduction of open cows into the herd are good preventative practices. An estimated 42% of cows will acquire the disease if bred to an infected bull.[9]

The long term prognosis for cats with TF is generally good, the diarrhoea will usually resolve itself in untreated cats. However this can take many months, and cats which no longer show clinical signs can continue to excrete the organism for up to two years.[10] It appears that over time the parasite dies off and the infection is remedied on its own. In some cases, the symptoms may improve over time, but the animal is likely to still be a carrier of the parasite, capable of transmitting it to another cat.

Treatment with ronidazole has shown good efficacy, and some positive results may be achieved after just two to three days of treatment, but completion of the two week cycle of drugs to avoid the risk of recurrence. A further laboratory test after treatment will give a good indication to the efficacy of treatment. It is also recommended that a follow-up test be performed a few months after the first.

During and after treatment a special diet may be required. Since the organism resides in the colon of the feline, long-term infection may cause excessive damage to the colon. A special diet may be required for several months, depending on the length and severity of infection.

References

  1. ↑ Gookin, Jody L.; Martha E. Stebbins; Emily Hunt; Karen Burlone; Merritt Fulton; Robin Hochel; Miriam Talaat; Matthew Poore; Michael G. Levy (2004). "Prevalence of and Risk Factors for Feline Tritrichomonas foetus and Giardia Infection" (PDF). J Clin Microbiol. 42 (6): 2707–2710. doi:10.1128/JCM.42.6.2707-2710.2004. PMC 427826. PMID 15184456.
  2. ↑ Tritrichomonas foetus reviewed and published by WikiVet, accessed 10 October 2011.
  3. ↑ 3.0 3.1 3.2 Trichomonosis - Cattle reviewed and published by WikiVet, accessed 10 October 2011.
  4. ↑ 4.0 4.1 Felleisen, Richard S.J.; Natacha Lambelet; Philipp Bachmann; Jacques Nicolet; Norbert Müller; Bruno Gottstein (1998). "Detection of Tritrichomonas foetus by PCR and DNA Enzyme Immunoassay Based on rRNA Gene Unit Sequences". J Clin Microbiol. 36 (2): 513–519.
  5. ↑ InPouch TF
  6. ↑ http://www.cvm.ncsu.edu/docs/documents/ownersguide_tfoetus_revised_122009_final.pdf
  7. ↑ http://www.vcahospitals.com/main/pet-health-information/article/animal-health/ronidazole/786
  8. ↑ reviewed and published by Iowa State University College of Veterinary Medicine, accessed 30 April 2014.
  9. ↑ https://www.addl.purdue.edu/newsletters/2000/spring/bv.shtml accessed 30 April 2014.
  10. ↑ Tritrichomonas foetus in cats

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