What is known about Tritrichomonas foetus infection in cats?

O que sabemos sobre a infecção por Tritrichomonas foetus em gatos?

Bethânia Ferreira Bastos Flavya Mendes de Almeida Beatriz Brener About the authors

Abstract

Tritrichomonas foetus is a parasite that has been definitively identified as an agent of trichomonosis, a disease characterized by chronic diarrhea. T. foetus colonizes portions of the feline large intestine, and manifests as chronic and recurrent diarrhea with mucus and fresh blood, which is often unresponsive to common drugs. Diagnosis of a trichomonad infection is made by either the demonstration of the trophozoite on a direct fecal smear, fecal culture and subsequent microscopic examination of the parasite, or extraction of DNA in feces and amplification by the use of molecular tools. T. foetus is commonly misidentified as other flagellate protozoa such as Giardia duodenalis and Pentatrichomonas hominis. Without proper treatment, the diarrhea may resolve spontaneously in months to years, but cats can remain carriers of the parasite. This paper intends to serve as a source of information for investigators and veterinarians, reviewing the most important aspects of feline trichomonosis, such as trichomonad history, biology, clinical manifestations, pathogenesis, world distribution, risk factors, diagnosis, and treatment.

Keywords:
Trichomonosis; domestic cat; diarrhea; endoparasites

Resumo

Tritrichomonas foetus é um parasito que foi identificado definitivamente como agente de tricomoníase, caracterizada por diarreia crônica. T. foetus coloniza porções do intestino grosso dos felinos e se manifesta como uma diarreia crônica e recorrente, com muco e sangue, geralmente irresponsiva às drogas comumente usadas no tratamento. O diagnóstico da infecção por tricomonadídeos é feito pela demonstração de trofozoítos no exame direto de fezes frescas, cultura fecal e subsequente exame microscópico ou extração do DNA do parasito na amostra fecal e amplificação, utilizando-se técnicas moleculares. T. foetus é comumente confundido com outros protozoários flagelados, como Giardia duodenalis e Pentatrichomonas hominis. Sem tratamento adequado, a diarreia pode cessar espontaneamente em meses ou anos, porém os gatos podem permanecer portadores do parasito. Esse artigo pretende servir como fonte de informação para pesquisadores e veterinários, revisando os mais importantes aspectos da tricomoníase felina, como histórico, biologia, manifestações clínicas, patogênese, distribuição mundial, fatores de risco, diagnóstico e tratamento.

Palavras-chave:
Trichomoníase; gato doméstico; diarreia; endoparasitos

Introduction

Tritrichomonas foetus is a trichomonad that was first described as a bovine venereal pathogen, causing infertility, abortion, and endometritis ( FELLEISEN, 1999 Felleisen RS. Host-parasite interaction in bovine infection with Tritrichomonas foetus. Microbes Infect 1999; 1(10): 807-816. http://dx.doi.org/10.1016/S1286-4579(99)80083-5. PMid:10816086.
http://dx.doi.org/10.1016/S1286-4579(99...
; STOCKDALE et al., 2006 Stockdale HD, Spencer JA, Dykstra CC, Blagburn BL, West GS, Hankes T, et al. Feline trichomoniasis: an emerging disease? Compend Contin Educ Vet 2006; 28(6): 463-471. ). More than a decade ago, T. foetus was also identified in the feces of domestic cats with chronic diarrhea ( GOOKIN et al., 1999 Gookin JL, Breitschwerdt EB, Levy MG, Gager RB, Benrud JG. Diarrhea associated with trichomonosis in cats. J Am Vet Med Assoc 1999; 215(10): 1450-1454. PMid:10579040. ; LEVY et al., 2003 Levy MG, Gookin JL, Poore M, Birkenheuer AJ, Dykstra MJ, Litaker RW. Tritrichomonas foetus and not Pentatrichomonas hominis is the etiologic agent of feline trichomonal diarrhea. J Parasitol 2003; 89(1): 99-104. http://dx.doi.org/10.1645/0022-3395(2003)089[0099:TFANPH]2.0.CO;2. PMid:12659310.
http://dx.doi.org/10.1645/0022-3395(200...
). Trichomonads had been observed in cats with and without diarrhea (DA CUNHA & MUNIZ, 1922 DaCunha AM, Muniz J. Sobre um flagellado parasito do gato. Trab Inst Oswaldo Cruz 1922; 36: 285-286. ; JORDAN, 1956 Jordan HE. Trichomonas spp. in feline: a case report. Vet Med 1956; 51: 23-24. ), but was considered to be commensal and opportunistic ( DIMSKI, 1989 Dimski DS. Helminth and noncoccidial protozoan parasites of the gastrointestinal tract. In: Sherding RG, editors. The Cat: Diseases and Clinical Management, 2nd ed. New York: Churchill Livingstone; 1989. p. 459-477. ; BARR, 1998 Barr SC. Enteric protozoal infections. In: Greene CE. Infectious diseases of the dog and cat. 2nd ed. Philadelphia: WB Saunders; 1998. p. 482-91. ). For a long time, T. foetus may have been confused with Pentatrichomonas sp. or Giardia sp. under microscopic analysis ( GOOKIN et al., 1999 Gookin JL, Breitschwerdt EB, Levy MG, Gager RB, Benrud JG. Diarrhea associated with trichomonosis in cats. J Am Vet Med Assoc 1999; 215(10): 1450-1454. PMid:10579040. ); however, with genetic identification through molecular tools, T. foetus was considered the causal agent of feline trichomonosis in 2003 ( LEVY et al., 2003 Levy MG, Gookin JL, Poore M, Birkenheuer AJ, Dykstra MJ, Litaker RW. Tritrichomonas foetus and not Pentatrichomonas hominis is the etiologic agent of feline trichomonal diarrhea. J Parasitol 2003; 89(1): 99-104. http://dx.doi.org/10.1645/0022-3395(2003)089[0099:TFANPH]2.0.CO;2. PMid:12659310.
http://dx.doi.org/10.1645/0022-3395(200...
).

Since feline trichomonosis has been identified as an emerging gastrointestinal disease, researchers have turned their interest to understanding its etiology, epidemiology, and pathogenesis, as well as diagnosis and treatment ( GOOKIN et al., 1999 Gookin JL, Breitschwerdt EB, Levy MG, Gager RB, Benrud JG. Diarrhea associated with trichomonosis in cats. J Am Vet Med Assoc 1999; 215(10): 1450-1454. PMid:10579040. , 2006 Gookin JL, Copple CN, Papich MG, Poore MF, Stauffer SH, Birkenheuer AJ, et al. Efficacy of ronidazole for treatment of feline Tritrichomonas foetus infection. J Vet Intern Med 2006; 20(3): 536-543. http://dx.doi.org/10.1111/j.1939-1676.2006.tb02893.x. PMid:16734086.
http://dx.doi.org/10.1111/j.1939-1676.2...
, 2010 Gookin JL, Stone MR, Yaeger MJ, Meyerholz DK, Moisan P. Fluorescence in situ hybridization for identification of Tritrichomonas foetus in formalin-fixed and paraffin-embedded histological specimens of intestinal trichomoniasis. Vet Parasitol 2010; 172(1-2): 139-143. http://dx.doi.org/10.1016/j.vetpar.2010.04.014. PMid:20447769.
http://dx.doi.org/10.1016/j.vetpar.2010...
; GRAY et al., 2010 Gray SG, Hunter AS, Stone MR, Gookin JL. Assessment of reproductive tract disease in cats at risk for Tritrichomonas foetus infection. Am J Vet Res 2010; 71(1): 76-81. http://dx.doi.org/10.2460/ajvr.71.1.76. PMid:20043785.
http://dx.doi.org/10.2460/ajvr.71.1.76 ...
).

Taxonomy

Trichomonads of the species Tritrichomonas foetus are anaerobic protozoan parasites placed in the phylum Parabasalia, order Trichomonadida, and family Trichomonadidae ( BRUGEROLLE & LEE, 2000 Brugerolle G, Lee J. Phylum Parabasalia. In: Lee J, Leedale G, Bradbury P (eds.). The Illustrated Guide to the Protozoa. 2nd ed. Society of Protozoologists, Lawrence; 2000. p. 1196-1210. ). A new rank system classifies trichomonads as [Excavata: Parabasalia: Trichomonadida] ( ADL et al., 2005 Adl SM, Simpson AG, Farmer MA, Andersen RA, Anderson OR, Barta JR, et al. The new higher level classification of eukaryotes with emphasis on the taxonomy of protists. J Eukaryot Microbiol 2005; 52(5): 399-451. http://dx.doi.org/10.1111/j.1550-7408.2005.00053.x. PMid:16248873.
http://dx.doi.org/10.1111/j.1550-7408.2...
).

History

Trichomonosis was first described in a cat in Brazil by Da Cunha & Muniz (1922 DaCunha AM, Muniz J. Sobre um flagellado parasito do gato. Trab Inst Oswaldo Cruz 1922; 36: 285-286. ), who named the agent Trichomonas felis. Years later, Brumpt (1925) Brumpt E. Recherches morphologiques et expérimentales sur le Trichomonas felis Da Cunha et Muniz, 1922, parasite du chat et du chien. Ann Parasitol Hum Comp 1925; 3(3): 239-251. http://dx.doi.org/10.1051/parasite/1925033239.
http://dx.doi.org/10.1051/parasite/1925...
found trichomonads with three to five anterior flagella in dogs and cats in France, adopting the name Trichomonas felis for the parasite present in both animals. One year later, Tanabe identified Pentatrichomonas sp. in a cat, naming the parasite Pentatrichomonas felis ( TANABE, 1926 Tanabe M. Morphological studies on trichomonas. J Parasitol 1926; 12(3): 120-130. http://dx.doi.org/10.2307/3271220.
http://dx.doi.org/10.2307/3271220 ...
).

Kessel (1928) Kessel JF. Trichomoniasis in kittens. Trans R Soc Trop Med Hyg 1928; 22(1): 61-80. http://dx.doi.org/10.1016/S0035-9203(28)90155-8.
http://dx.doi.org/10.1016/S0035-9203(28...
observed natural and experimental trichomonosis in nine kittens. These animals presented with diarrhea that progressed to dysentery, and they died within 10 days of infection.

In 1956, a young cat presenting with chronic diarrhea was diagnosed with trichomonosis, described as an infection caused by Trichomonas sp. ( JORDAN, 1956 Jordan HE. Trichomonas spp. in feline: a case report. Vet Med 1956; 51: 23-24. ).

From 1956 to 1996, there was a lack of reports about feline trichomonosis, presumably because of the assumption that the trichomonads were non-pathogenic commensal species and only existed when there was a pre-existing enteric disease ( DIMSKI, 1989 Dimski DS. Helminth and noncoccidial protozoan parasites of the gastrointestinal tract. In: Sherding RG, editors. The Cat: Diseases and Clinical Management, 2nd ed. New York: Churchill Livingstone; 1989. p. 459-477. ; BARR, 1998 Barr SC. Enteric protozoal infections. In: Greene CE. Infectious diseases of the dog and cat. 2nd ed. Philadelphia: WB Saunders; 1998. p. 482-91. ; GOOKIN et al., 1999 Gookin JL, Breitschwerdt EB, Levy MG, Gager RB, Benrud JG. Diarrhea associated with trichomonosis in cats. J Am Vet Med Assoc 1999; 215(10): 1450-1454. PMid:10579040. ). In 1996, based on the microscopic examination of fecal smears, Romatowski (1996 Romatowski J. An uncommon protozoan parasite (Pentatrichomonas hominis ) associated with colitis in three cats. Feline Pract 1996; 24(5): 10-14. , 2000 Romatowski J. Pentatrichomonas hominis infection in four kittens. J Am Vet Med Assoc 2000; 216(8): 1270-1272. http://dx.doi.org/10.2460/javma.2000.216.1270. PMid:10767968.
http://dx.doi.org/10.2460/javma.2000.21...
) identified the trichomonads as Pentatrichomonas hominis, and causing a mucoid diarrhea in kittens and adult cats.

In 2001, after a molecular assay to analyze the gene 18S rRNA present in trichomonad isolates, the identity of the agent as Tritrichomonas foetus was revealed, with 99.9% similarity ( LEVY et al., 2003 Levy MG, Gookin JL, Poore M, Birkenheuer AJ, Dykstra MJ, Litaker RW. Tritrichomonas foetus and not Pentatrichomonas hominis is the etiologic agent of feline trichomonal diarrhea. J Parasitol 2003; 89(1): 99-104. http://dx.doi.org/10.1645/0022-3395(2003)089[0099:TFANPH]2.0.CO;2. PMid:12659310.
http://dx.doi.org/10.1645/0022-3395(200...
).

Tritrichomonas foetus has also been identified in the reproductive tract of a cat with pyometra in Norway, although the cause of the uterine infection was attributed to the bacteria Streptococcus sp., which was present in the genital secretion ( DAHLGREN et al., 2007 Dahlgren SS, Gjerde B, Pettersen HY. First record of natural Tritrichomonas foetus infection of the feline uterus. J Small Anim Pract 2007; 48(11): 654-657. http://dx.doi.org/10.1111/j.1748-5827.2007.00405.x. PMid:17725583.
http://dx.doi.org/10.1111/j.1748-5827.2...
).

Gray et al. (2010) Gray SG, Hunter AS, Stone MR, Gookin JL. Assessment of reproductive tract disease in cats at risk for Tritrichomonas foetus infection. Am J Vet Res 2010; 71(1): 76-81. http://dx.doi.org/10.2460/ajvr.71.1.76. PMid:20043785.
http://dx.doi.org/10.2460/ajvr.71.1.76 ...
examined the reproductive tracts of 15 cats previously diagnosed with intestinal infection caused by T. foetus. They used light microscopy, immunohistochemical analysis, and PCR assay, and found no evidence of the parasite in the reproductive tracts.

Molecular Approach

Several studies have investigated the agent present in cattle and the possibility that this was the source of the feline infection. An epidemiological study of cats found no association between T. foetus infection and proximity to cattle ( GOOKIN et al., 2004 Gookin JL, Stebbins ME, Hunt E, Burlone K, Fulton M, Hochel R, et al. Prevalence of and risk factors for feline Tritrichomonas foetus and Giardia infection. J Clin Microbiol 2004; 42(6): 2707-2710. http://dx.doi.org/10.1128/JCM.42.6.2707-2710.2004. PMid:15184456.
http://dx.doi.org/10.1128/JCM.42.6.2707...
). Studies involving cross-transmission conducted by Stockdale et al. (2007 Stockdale H, Rodning S, Givens M, Carpenter D, Lenz S, Spencer J, et al. Experimental infection of cattle with a feline isolate of Tritrichomonas foetus. J Parasitol 2007; 93(6): 1429-1434. http://dx.doi.org/10.1645/GE-1305.1. PMid:18314690.
http://dx.doi.org/10.1645/GE-1305.1 ...
, 2008 Stockdale HD, Dillon AR, Newton JC, Bird RC, Bondurant RH, Deinnocentes P, et al. Experimental infection of cats (Felis catus) with Tritrichomonas foetus isolated from cattle. Vet Parasitol 2008; 154(1-2): 156-161. http://dx.doi.org/10.1016/j.vetpar.2008.02.024. PMid:18394809.
http://dx.doi.org/10.1016/j.vetpar.2008...
) indicated phenotypic differences related to infectivity and pathogenicity among the feline and bovine isolates. The molecular characterization of feline isolates compared to cattle showed genetic differences. Thus, Slapeta et al. (2010) Slapeta J, Craig S, McDonell D, Emery D. Tritrichomonas foetus from domestic cats and cattle are genetically distinct. Exp Parasitol 2010; 126(2): 209-213. http://dx.doi.org/10.1016/j.exppara.2010.04.024. PMid:20438726.
http://dx.doi.org/10.1016/j.exppara.201...
suggested a species-specific distinction of T. foetus between the cattle and cat genotypes. Other researchers have also observed few but consistent genetic differences between cattle and feline isolates. Sun et al. (2012) Sun Z, Stack C, Slapeta J. Sequence differences in the diagnostic region of the cysteine protease 8 gene of Tritrichomonas foetus parasites of cats and cattle. Vet Parasitol 2012; 186(3-4): 445-449. http://dx.doi.org/10.1016/j.vetpar.2011.12.001. PMid:22204891.
http://dx.doi.org/10.1016/j.vetpar.2011...
reported differences in the nucleotides and amino acids of cysteine protease 8 from bovine and feline isolates, elucidating a possible adaptation to their preferred host.

A new name, Tritrichomonas blagburni, was proposed for the feline parasite in order to differentiate it from the bovine parasite ( WALDEN et al., 2013 Walden HS, Dykstra C, Dillon A, Rodning S, Givens D, Bird R, et al. A new species of Tritrichomonas (Sarcomastigophora: Trichomonida) from the domestic cat (Felis catus ). Parasitol Res 2013; 112(6): 2227-2235. http://dx.doi.org/10.1007/s00436-013-3381-8. PMid:23525691.
http://dx.doi.org/10.1007/s00436-013-33...
). According to the authors, the host specificity, as well as morphological and genetic information, must be considered in any taxonomic evaluation. This is still scientifically controversial, since data obtained from comparative analyzes of the two transcriptomes have failed to confirm that they are two distinct species ( MORIN-ADELINE et al., 2014 Morin-Adeline V, Lomas R, O’Meally D, Stack C, Conesa A, Šlapeta J. Comparative transcriptomics reveals striking similarities between the bovine and feline isolates of Tritrichomonas foetus: consequences for in silico drug-target identification. BMC Genomics 2014; 15(1): 955. http://dx.doi.org/10.1186/1471-2164-15-955. PMid:25374366.
http://dx.doi.org/10.1186/1471-2164-15-...
).

In addition, studies suggested that T. suis, a trichomonad of the domestic pig, is morphologically indistinguishable from T. foetus. Sequencing of a variable DNA fragment and comparison of gene sequences did not reveal differences between T. suis and T. foetus bovine isolates. Thus, researchers concluded that T. foetus and T. suis belong to the same species, proposing that they are synonyms ( TACHEZY et al., 2002 Tachezy J, Tachezy R, Hampl V, Sedinová M, Vanacová S, Vrlík M, et al. Cattle pathogen Tritrichomonas foetus (Riedmuller, 1928) and pig commensal Tritrichomonas suis (Gruby & Delafond, 1843) belong to the same species. J Eukaryot Microbiol 2002; 49(2): 154-163. http://dx.doi.org/10.1111/j.1550-7408.2002.tb00360.x. PMid:12046599.
http://dx.doi.org/10.1111/j.1550-7408.2...
; LUN et al., 2005 Lun ZR, Chen XG, Zhu XQ, Li XR, Xie MQ. Are Tritrichomonas foetus and Tritrichomonas suis synonyms? Trends Parasitol 2005; 21(3): 122-125. http://dx.doi.org/10.1016/j.pt.2004.12.001. PMid:15734659.
http://dx.doi.org/10.1016/j.pt.2004.12....
).

Morphology

The parasites T. foetus only have a trophozoite stage. They are small flagellates, ranging in size from 10–25 µm in length and 3–15 µm in width ( GOOKIN et al., 2006 Gookin JL, Copple CN, Papich MG, Poore MF, Stauffer SH, Birkenheuer AJ, et al. Efficacy of ronidazole for treatment of feline Tritrichomonas foetus infection. J Vet Intern Med 2006; 20(3): 536-543. http://dx.doi.org/10.1111/j.1939-1676.2006.tb02893.x. PMid:16734086.
http://dx.doi.org/10.1111/j.1939-1676.2...
). They have a pear-shaped body, one nucleus, three anterior flagella, and a posterior flagellum ( WARTON̄A & HONIGBERG, 1979 Warton̄a A, Honigberg BM. Structure of trichomonads as revealed by scanning electron microscopy. J Protozool 1979; 26(1): 56-62. http://dx.doi.org/10.1111/j.1550-7408.1979.tb02732.x. PMid:314517.
http://dx.doi.org/10.1111/j.1550-7408.1...
). The posterior flagellum travels along the body of the parasite, forming the undulating membrane ( GOOKIN et al., 2006 Gookin JL, Copple CN, Papich MG, Poore MF, Stauffer SH, Birkenheuer AJ, et al. Efficacy of ronidazole for treatment of feline Tritrichomonas foetus infection. J Vet Intern Med 2006; 20(3): 536-543. http://dx.doi.org/10.1111/j.1939-1676.2006.tb02893.x. PMid:16734086.
http://dx.doi.org/10.1111/j.1939-1676.2...
). The axostyle, a rigid organelle, extends through the body length of the parasite ( LEVINE, 1985 LeVine DN. Veterinary Protozoology, 1st ed. Ames: ISU Press; 1985. ), and protrudes from the posterior extremity ( GOOKIN et al., 2006 Gookin JL, Copple CN, Papich MG, Poore MF, Stauffer SH, Birkenheuer AJ, et al. Efficacy of ronidazole for treatment of feline Tritrichomonas foetus infection. J Vet Intern Med 2006; 20(3): 536-543. http://dx.doi.org/10.1111/j.1939-1676.2006.tb02893.x. PMid:16734086.
http://dx.doi.org/10.1111/j.1939-1676.2...
).

Life Cycle

The life cycle is a simple asexual cycle, where the trophozoite multiplies by longitudinal binary division, and transmission occurs directly between hosts via ingestion of trophozoites ( GOOKIN et al., 2017 Gookin JL, Hanrahan K, Levy MG. The conundrum of feline trichomonosis. J Feline Med Surg 2017; 19(3): 261-274. http://dx.doi.org/10.1177/1098612X17693499. PMid:28245739.
http://dx.doi.org/10.1177/1098612X17693...
).

There is no true cyst stage, but some authors describe that in conditions of environmental stress, such as nutrient scarcity, drug action, or abrupt temperature changes, there may be pseudo-cyst formation. In this case, the flagella are internalized, but the cell is not surrounded by a cyst wall ( PEREIRA-NEVES et al., 2003 Pereira-Neves A, Ribeiro KC, Benchimol M. Pseudocysts in trichomonads - new insights. Protist 2003; 154(3-4): 313-329. http://dx.doi.org/10.1078/143446103322454095. PMid:14658492.
http://dx.doi.org/10.1078/1434461033224...
; PEREIRA-NEVES & BENCHIMOL, 2009 Pereira-Neves A, Benchimol M. Tritrichomonas foetus: budding from multinucleated pseudocysts. Protist 2009; 160(4): 536-551. http://dx.doi.org/10.1016/j.protis.2009.05.001. PMid:19616999.
http://dx.doi.org/10.1016/j.protis.2009...
; ROSA et al., 2015 Rosa IA, Souza W, Benchimol M. Changes in the structural organization of the cytoskeleton of Tritrichomonas foetus during trophozoite-pseudocyst transformation. Micron 2015; 73: 28-35. http://dx.doi.org/10.1016/j.micron.2015.03.008. PMid:25880467.
http://dx.doi.org/10.1016/j.micron.2015...
).

Transmission

The transmission of T. foetus among cats occurs via the fecal–oral route ( GOOKIN et al., 1999 Gookin JL, Breitschwerdt EB, Levy MG, Gager RB, Benrud JG. Diarrhea associated with trichomonosis in cats. J Am Vet Med Assoc 1999; 215(10): 1450-1454. PMid:10579040. , 2001 Gookin JL, Levy MG, Law JM, Papich MG, Poore MF, Breitschwerdt EB. Experimental infection of cats with Tritrichomonas foetus. Am J Vet Res 2001; 62(11): 1690-1697. http://dx.doi.org/10.2460/ajvr.2001.62.1690. PMid:11703009.
http://dx.doi.org/10.2460/ajvr.2001.62....
). Direct contact with contaminated fresh feces may be sufficient for the transmission of the parasite, since T. foetus does not release cysts into the environment. However, Hale et al. (2009) Hale S, Norris JM, Slapeta J. Prolonged resilience of Tritrichomonas foetus in cat faeces at ambient temperature. Vet Parasitol 2009; 166(1-2): 60-65. http://dx.doi.org/10.1016/j.vetpar.2009.07.032. PMid:19683398.
http://dx.doi.org/10.1016/j.vetpar.2009...
showed that T. foetus trophozoites are more resistant to environmental conditions than previously thought, surviving in moist feces for seven days at room temperature (23-24°C). The ability of the parasite to survive outside the host may be an important factor in the epidemiology of the disease, especially in places with an overpopulation of cats. This survivability also suggests that self and mutual grooming by cats and fecal contamination of the environment are important factors in the epidemiology of the disease ( HALE et al., 2009 Hale S, Norris JM, Slapeta J. Prolonged resilience of Tritrichomonas foetus in cat faeces at ambient temperature. Vet Parasitol 2009; 166(1-2): 60-65. http://dx.doi.org/10.1016/j.vetpar.2009.07.032. PMid:19683398.
http://dx.doi.org/10.1016/j.vetpar.2009...
; VAN DER SAAG et al., 2010 Van der Saag M, McDonell D, Slapeta J. Cat genotype Tritrichomonas foetus survives passage through the alimentary tract of two common slug species. Vet Parasitol 2010; 177(3-4): 262-266. http://dx.doi.org/10.1016/j.vetpar.2010.11.054. PMid:21185122.
http://dx.doi.org/10.1016/j.vetpar.2010...
).

Although the experimental transmission of T. foetus between cattle and felines is possible, direct transmission from bovines to cats is not the primary source of infection ( STOCKDALE et al., 2008 Stockdale HD, Dillon AR, Newton JC, Bird RC, Bondurant RH, Deinnocentes P, et al. Experimental infection of cats (Felis catus) with Tritrichomonas foetus isolated from cattle. Vet Parasitol 2008; 154(1-2): 156-161. http://dx.doi.org/10.1016/j.vetpar.2008.02.024. PMid:18394809.
http://dx.doi.org/10.1016/j.vetpar.2008...
). Gookin et al. (2004) Gookin JL, Stebbins ME, Hunt E, Burlone K, Fulton M, Hochel R, et al. Prevalence of and risk factors for feline Tritrichomonas foetus and Giardia infection. J Clin Microbiol 2004; 42(6): 2707-2710. http://dx.doi.org/10.1128/JCM.42.6.2707-2710.2004. PMid:15184456.
http://dx.doi.org/10.1128/JCM.42.6.2707...
found no association between feline infection and proximity to cattle.

Risk Factors

Tritrichomonas foetus is predominantly identified in young cats. Most studies have shown an average age of 12 months or less, ranging in age from 4 weeks to 16 years ( GOOKIN et al., 1999 Gookin JL, Breitschwerdt EB, Levy MG, Gager RB, Benrud JG. Diarrhea associated with trichomonosis in cats. J Am Vet Med Assoc 1999; 215(10): 1450-1454. PMid:10579040. , 2004 Gookin JL, Stebbins ME, Hunt E, Burlone K, Fulton M, Hochel R, et al. Prevalence of and risk factors for feline Tritrichomonas foetus and Giardia infection. J Clin Microbiol 2004; 42(6): 2707-2710. http://dx.doi.org/10.1128/JCM.42.6.2707-2710.2004. PMid:15184456.
http://dx.doi.org/10.1128/JCM.42.6.2707...
; BURGENER et al., 2009 Burgener I, Frey CF, Kook P, Gottstein B. Tritrichomonas foetus: a new intestinal parasite in Swiss cats. Schweiz Arch Tierheilkd 2009; 151(8): 383-389. http://dx.doi.org/10.1024/0036-7281.151.8.383. PMid:19653162.
http://dx.doi.org/10.1024/0036-7281.151...
; FREY et al., 2009 Frey CF, Schild M, Hemphill A, Stünzi P, Müller N, Gottstein B, et al. Intestinal Tritrichomonas foetus infection in cats in Switzerland detected by in vitro cultivation and PCR. Parasitol Res 2009; 104(4): 783-788. http://dx.doi.org/10.1007/s00436-008-1255-2. PMid:18998166.
http://dx.doi.org/10.1007/s00436-008-12...
).

In many studies, infected cats were 1 year old or younger ( FOSTER et al., 2004 Foster DM, Gookin JL, Poore MF, Stebbins ME, Levy MG. Outcome of cats with diarrhea and Tritrichomonas foetus infection. J Am Vet Med Assoc 2004; 225(6): 888-892. http://dx.doi.org/10.2460/javma.2004.225.888. PMid:15485048.
http://dx.doi.org/10.2460/javma.2004.22...
; GOOKIN et al., 2004 Gookin JL, Stebbins ME, Hunt E, Burlone K, Fulton M, Hochel R, et al. Prevalence of and risk factors for feline Tritrichomonas foetus and Giardia infection. J Clin Microbiol 2004; 42(6): 2707-2710. http://dx.doi.org/10.1128/JCM.42.6.2707-2710.2004. PMid:15184456.
http://dx.doi.org/10.1128/JCM.42.6.2707...
; YAEGER & GOOKIN, 2005 Yaeger MJ, Gookin JL. Histologic features associated with Tritrichomonas foetus induced colitis in domestic cats. Vet Pathol 2005; 42(6): 797-804. http://dx.doi.org/10.1354/vp.42-6-797. PMid:16301576.
http://dx.doi.org/10.1354/vp.42-6-797 ...
; STOCKDALE et al., 2009 Stockdale HD, Givens MD, Dykstra CC, Blagburn BL. Tritrichomonas foetus infections in surveyed pet cats. Vet Parasitol 2009; 160(1-2): 13-17. http://dx.doi.org/10.1016/j.vetpar.2008.10.091. PMid:19070434.
http://dx.doi.org/10.1016/j.vetpar.2008...
; ARRANZ-SOLÍS et al., 2016 Arranz-Solís D, Pedraza-Díaz S, Miró G, Rojo-Montejo S, Hernández L, Ortega-Mora LM, et al. Tritrichomonas foetus infection in cats with diarrhea from densely housed origins. Vet Parasitol 2016; 221: 118-122. http://dx.doi.org/10.1016/j.vetpar.2016.03.019. PMid:27084482.
http://dx.doi.org/10.1016/j.vetpar.2016...
). Holliday et al. (2009) Holliday M, Deni D, Gunn-Moore DA. Tritrichomonas foetus infection in cats with diarrhoea in a rescue colony in Italy. J Feline Med Surg 2009; 11(2): 131-134. http://dx.doi.org/10.1016/j.jfms.2008.06.004. PMid:18774326.
http://dx.doi.org/10.1016/j.jfms.2008.0...
found infected cats in a colony with a predominant age of over 1 year. The probable explanation for this discrepancy is that the infection may have entered the population for the first time, and the lack of protection by the immune system allowed older cats as well as young cats to develop clinical signs ( HOLLIDAY et al., 2009 Holliday M, Deni D, Gunn-Moore DA. Tritrichomonas foetus infection in cats with diarrhoea in a rescue colony in Italy. J Feline Med Surg 2009; 11(2): 131-134. http://dx.doi.org/10.1016/j.jfms.2008.06.004. PMid:18774326.
http://dx.doi.org/10.1016/j.jfms.2008.0...
). Cats, especially those more than 3 years old, may be asymptomatically infected, and can become an important source of parasitic infection for other felines ( XENOULIS et al., 2010 Xenoulis PG, Saridomichelakis MN, Read SA, Suchodolski JS, Steiner JM. Detection of Tritrichomonas foetus in cats in Greece. J Feline Med Surg 2010; 12(10): 831-833. http://dx.doi.org/10.1016/j.jfms.2010.05.010. PMid:20674428.
http://dx.doi.org/10.1016/j.jfms.2010.0...
).

A predisposition to gender among cats infected with T. foetus has not been observed in any study ( GOOKIN et al., 2004 Gookin JL, Stebbins ME, Hunt E, Burlone K, Fulton M, Hochel R, et al. Prevalence of and risk factors for feline Tritrichomonas foetus and Giardia infection. J Clin Microbiol 2004; 42(6): 2707-2710. http://dx.doi.org/10.1128/JCM.42.6.2707-2710.2004. PMid:15184456.
http://dx.doi.org/10.1128/JCM.42.6.2707...
; GUNN-MOORE et al., 2007 Gunn-Moore DA, McCann TM, Reed N, Simpson KE, Tennant B. Prevalence of Tritrichomonas foetus infection in cats with diarrhoea in the UK. J Feline Med Surg 2007; 9(3): 214-218. http://dx.doi.org/10.1016/j.jfms.2007.01.003. PMid:17446107.
http://dx.doi.org/10.1016/j.jfms.2007.0...
; BURGENER et al., 2009 Burgener I, Frey CF, Kook P, Gottstein B. Tritrichomonas foetus: a new intestinal parasite in Swiss cats. Schweiz Arch Tierheilkd 2009; 151(8): 383-389. http://dx.doi.org/10.1024/0036-7281.151.8.383. PMid:19653162.
http://dx.doi.org/10.1024/0036-7281.151...
; STOCKDALE et al., 2009 Stockdale HD, Givens MD, Dykstra CC, Blagburn BL. Tritrichomonas foetus infections in surveyed pet cats. Vet Parasitol 2009; 160(1-2): 13-17. http://dx.doi.org/10.1016/j.vetpar.2008.10.091. PMid:19070434.
http://dx.doi.org/10.1016/j.vetpar.2008...
). In most studies, purebred cats are more affected ( GUNN-MOORE et al., 2007 Gunn-Moore DA, McCann TM, Reed N, Simpson KE, Tennant B. Prevalence of Tritrichomonas foetus infection in cats with diarrhoea in the UK. J Feline Med Surg 2007; 9(3): 214-218. http://dx.doi.org/10.1016/j.jfms.2007.01.003. PMid:17446107.
http://dx.doi.org/10.1016/j.jfms.2007.0...
; BURGENER et al., 2009 Burgener I, Frey CF, Kook P, Gottstein B. Tritrichomonas foetus: a new intestinal parasite in Swiss cats. Schweiz Arch Tierheilkd 2009; 151(8): 383-389. http://dx.doi.org/10.1024/0036-7281.151.8.383. PMid:19653162.
http://dx.doi.org/10.1024/0036-7281.151...
; FREY et al., 2009 Frey CF, Schild M, Hemphill A, Stünzi P, Müller N, Gottstein B, et al. Intestinal Tritrichomonas foetus infection in cats in Switzerland detected by in vitro cultivation and PCR. Parasitol Res 2009; 104(4): 783-788. http://dx.doi.org/10.1007/s00436-008-1255-2. PMid:18998166.
http://dx.doi.org/10.1007/s00436-008-12...
; STOCKDALE et al., 2009 Stockdale HD, Givens MD, Dykstra CC, Blagburn BL. Tritrichomonas foetus infections in surveyed pet cats. Vet Parasitol 2009; 160(1-2): 13-17. http://dx.doi.org/10.1016/j.vetpar.2008.10.091. PMid:19070434.
http://dx.doi.org/10.1016/j.vetpar.2008...
; BELL et al., 2010 Bell ET, Gowan RA, Lingard AE, McCoy RJ, Slapeta J, Malik R. Naturally occurring Tritrichomonas foetus infections in Australian cats: 38 cases. J Feline Med Surg 2010; 12(12): 889-898. http://dx.doi.org/10.1016/j.jfms.2010.06.003. PMid:20817588.
http://dx.doi.org/10.1016/j.jfms.2010.0...
; KLEIN et al., 2010 Klein B, Langbein-Detsch I, Muller E, Heusinger A. Prävalenz von Tritrichomonas foetus in Kotproben von Katzen mit Durchfall aus Deutschland. Kleintiermedizin 2010; 7/8: 243-247. ). Conversely, two studies have shown that the infection is also common in mixed-breed cats ( GOOKIN et al., 1999 Gookin JL, Breitschwerdt EB, Levy MG, Gager RB, Benrud JG. Diarrhea associated with trichomonosis in cats. J Am Vet Med Assoc 1999; 215(10): 1450-1454. PMid:10579040. ; HOLLIDAY et al., 2009 Holliday M, Deni D, Gunn-Moore DA. Tritrichomonas foetus infection in cats with diarrhoea in a rescue colony in Italy. J Feline Med Surg 2009; 11(2): 131-134. http://dx.doi.org/10.1016/j.jfms.2008.06.004. PMid:18774326.
http://dx.doi.org/10.1016/j.jfms.2008.0...
). Since feline infection by T. foetus is more frequent in catteries and shelters ( GOOKIN et al., 1999 Gookin JL, Breitschwerdt EB, Levy MG, Gager RB, Benrud JG. Diarrhea associated with trichomonosis in cats. J Am Vet Med Assoc 1999; 215(10): 1450-1454. PMid:10579040. ; FOSTER et al., 2004 Foster DM, Gookin JL, Poore MF, Stebbins ME, Levy MG. Outcome of cats with diarrhea and Tritrichomonas foetus infection. J Am Vet Med Assoc 2004; 225(6): 888-892. http://dx.doi.org/10.2460/javma.2004.225.888. PMid:15485048.
http://dx.doi.org/10.2460/javma.2004.22...
), it is not known whether infection is more frequent in purebred cats because of a genetic predisposition or because these cats usually live in places with an agglomeration of T. foetus ( HOLLIDAY et al., 2009 Holliday M, Deni D, Gunn-Moore DA. Tritrichomonas foetus infection in cats with diarrhoea in a rescue colony in Italy. J Feline Med Surg 2009; 11(2): 131-134. http://dx.doi.org/10.1016/j.jfms.2008.06.004. PMid:18774326.
http://dx.doi.org/10.1016/j.jfms.2008.0...
).

The role of overpopulation and management in contrast to genetic predisposition may be the answer to the higher prevalence of infection in purebred cats. This explanation is supported by the high prevalence of infection in a group of mixed-breed cat residents in a shelter with poor sanitary conditions ( HOLLIDAY et al., 2009 Holliday M, Deni D, Gunn-Moore DA. Tritrichomonas foetus infection in cats with diarrhoea in a rescue colony in Italy. J Feline Med Surg 2009; 11(2): 131-134. http://dx.doi.org/10.1016/j.jfms.2008.06.004. PMid:18774326.
http://dx.doi.org/10.1016/j.jfms.2008.0...
).

Although Gookin et al. (2004) Gookin JL, Stebbins ME, Hunt E, Burlone K, Fulton M, Hochel R, et al. Prevalence of and risk factors for feline Tritrichomonas foetus and Giardia infection. J Clin Microbiol 2004; 42(6): 2707-2710. http://dx.doi.org/10.1128/JCM.42.6.2707-2710.2004. PMid:15184456.
http://dx.doi.org/10.1128/JCM.42.6.2707...
did not find a significant association between T. foetus infection and litter boxes, the importance of feline population density is associated with the facility of transmission through boxes ( GOOKIN et al., 2007 Gookin JL, Stauffer SH, Coccaro MR, Poore MF, Levy MG, Papich MG. Efficacy of tinidazole for treatment of cats experimentally infected with Tritrichomonas foetus. Am J Vet Res 2007; 68(10): 1085-1088. http://dx.doi.org/10.2460/ajvr.68.10.1085. PMid:17916015.
http://dx.doi.org/10.2460/ajvr.68.10.10...
).

It is not known whether the animal's immune status influences the pathogenesis of T. foetus infection. On the other hand, the high prevalence of infection in young cats may indicate a susceptibility to infection in the case of an immature immune system ( GOOKIN et al., 1999 Gookin JL, Breitschwerdt EB, Levy MG, Gager RB, Benrud JG. Diarrhea associated with trichomonosis in cats. J Am Vet Med Assoc 1999; 215(10): 1450-1454. PMid:10579040. ). However, an experimental study did not observe a worsening of the diarrhea when an immunosuppressive dose of prednisolone was administered ( GOOKIN et al., 2001 Gookin JL, Levy MG, Law JM, Papich MG, Poore MF, Breitschwerdt EB. Experimental infection of cats with Tritrichomonas foetus. Am J Vet Res 2001; 62(11): 1690-1697. http://dx.doi.org/10.2460/ajvr.2001.62.1690. PMid:11703009.
http://dx.doi.org/10.2460/ajvr.2001.62....
). In addition, there seems to be no association between T. foetus infection and immunosuppressive diseases, such as those caused by feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) ( GOOKIN et al., 1999 Gookin JL, Breitschwerdt EB, Levy MG, Gager RB, Benrud JG. Diarrhea associated with trichomonosis in cats. J Am Vet Med Assoc 1999; 215(10): 1450-1454. PMid:10579040. ; ROSADO et al., 2007 Rosado TW, Specht A, Marks SL. Neurotoxicosis in 4 cats receiving ronidazole. J Vet Intern Med 2007; 21(2): 328-331. http://dx.doi.org/10.1111/j.1939-1676.2007.tb02968.x. PMid:17427396.
http://dx.doi.org/10.1111/j.1939-1676.2...
).

Coinfections with other enteropathogens are often observed in cats with T. foetus ( GOOKIN et al., 2004 Gookin JL, Stebbins ME, Hunt E, Burlone K, Fulton M, Hochel R, et al. Prevalence of and risk factors for feline Tritrichomonas foetus and Giardia infection. J Clin Microbiol 2004; 42(6): 2707-2710. http://dx.doi.org/10.1128/JCM.42.6.2707-2710.2004. PMid:15184456.
http://dx.doi.org/10.1128/JCM.42.6.2707...
). Some authors question whether T. foetus is an isolated cause of diarrhea or if concomitant infections lead cats to be more vulnerable to the parasite ( STOCKDALE et al., 2009 Stockdale HD, Givens MD, Dykstra CC, Blagburn BL. Tritrichomonas foetus infections in surveyed pet cats. Vet Parasitol 2009; 160(1-2): 13-17. http://dx.doi.org/10.1016/j.vetpar.2008.10.091. PMid:19070434.
http://dx.doi.org/10.1016/j.vetpar.2008...
).

Several studies suggest that coinfection with Giardia sp. is common. Risk and associated factors common to trichomonosis and giardiasis include diarrhea, high population density, and young age ( GOOKIN et al., 2004 Gookin JL, Stebbins ME, Hunt E, Burlone K, Fulton M, Hochel R, et al. Prevalence of and risk factors for feline Tritrichomonas foetus and Giardia infection. J Clin Microbiol 2004; 42(6): 2707-2710. http://dx.doi.org/10.1128/JCM.42.6.2707-2710.2004. PMid:15184456.
http://dx.doi.org/10.1128/JCM.42.6.2707...
). Gookin et al. (2004) Gookin JL, Stebbins ME, Hunt E, Burlone K, Fulton M, Hochel R, et al. Prevalence of and risk factors for feline Tritrichomonas foetus and Giardia infection. J Clin Microbiol 2004; 42(6): 2707-2710. http://dx.doi.org/10.1128/JCM.42.6.2707-2710.2004. PMid:15184456.
http://dx.doi.org/10.1128/JCM.42.6.2707...
found a coinfection of T. foetus and Giardia sp. in 12% of the cats, but this association was not significant. Steiner et al. (2007) Steiner JM, Xenoulis PG, Read SA, Suchodolski JS, Globokar M, Huisinga E, et al. Identification of Tritrichomonas foetus DNA in feces from cats with diarrhea from Germany and Austria. J Vet Intern Med 2007; 21(3): 649. observed that most cats infected in their study were also positive for Giardia sp., and Bissett et al. (2008) Bissett SA, Gowan RA, O’Brien CR, Stone MR, Gookin JL. Feline diarrhoea associated with Tritrichomonas foetus and Giardia co-infection in an Australian cattery. Aust Vet J 2008; 86(11): 440-443. http://dx.doi.org/10.1111/j.1751-0813.2008.00356.x. PMid:18959533.
http://dx.doi.org/10.1111/j.1751-0813.2...
reported that 66% of cats studied were coinfected.

Coinfection with coccidia is also frequently reported ( STOCKDALE et al., 2009 Stockdale HD, Givens MD, Dykstra CC, Blagburn BL. Tritrichomonas foetus infections in surveyed pet cats. Vet Parasitol 2009; 160(1-2): 13-17. http://dx.doi.org/10.1016/j.vetpar.2008.10.091. PMid:19070434.
http://dx.doi.org/10.1016/j.vetpar.2008...
; GOOKIN et al., 2001 Gookin JL, Levy MG, Law JM, Papich MG, Poore MF, Breitschwerdt EB. Experimental infection of cats with Tritrichomonas foetus. Am J Vet Res 2001; 62(11): 1690-1697. http://dx.doi.org/10.2460/ajvr.2001.62.1690. PMid:11703009.
http://dx.doi.org/10.2460/ajvr.2001.62....
, 2005 Gookin JL, Birkenheuer AJ, St John V, Spector M, Levy MG. Molecular characterization of trichomonads from feces of dogs with diarrhea. J Parasitol 2005; 91(4): 939-943. http://dx.doi.org/10.1645/GE-474R.1. PMid:17089769.
http://dx.doi.org/10.1645/GE-474R.1 ...
; BISSETT et al., 2008 Bissett SA, Gowan RA, O’Brien CR, Stone MR, Gookin JL. Feline diarrhoea associated with Tritrichomonas foetus and Giardia co-infection in an Australian cattery. Aust Vet J 2008; 86(11): 440-443. http://dx.doi.org/10.1111/j.1751-0813.2008.00356.x. PMid:18959533.
http://dx.doi.org/10.1111/j.1751-0813.2...
). Gookin et al. (2001) Gookin JL, Levy MG, Law JM, Papich MG, Poore MF, Breitschwerdt EB. Experimental infection of cats with Tritrichomonas foetus. Am J Vet Res 2001; 62(11): 1690-1697. http://dx.doi.org/10.2460/ajvr.2001.62.1690. PMid:11703009.
http://dx.doi.org/10.2460/ajvr.2001.62....
experimentally inoculated eight cats with a feline T. foetus isolate, four of which were already infected with Cryptosporidium spp. After inoculation with the T. foetus isolate, cats infected with Cryptosporidium spp. developed earlier and more severe diarrhea and had a greater number of trophozoites in the direct exam than did cats without coccidia. On the other hand, there was no difference in the number of oocysts removed.

Prevalence

Studies with feline trichomonosis in several countries have indicated that T. foetus is prevalent among domestic cats around the world ( STEINER et al., 2007 Steiner JM, Xenoulis PG, Read SA, Suchodolski JS, Globokar M, Huisinga E, et al. Identification of Tritrichomonas foetus DNA in feces from cats with diarrhea from Germany and Austria. J Vet Intern Med 2007; 21(3): 649. ). In Brazil, there are only three reports of T. foetus infection in domestic cats. In Rio de Janeiro, Santos et al. (2015) Santos CS, Jesus VL, McIntosh D, Berto BP, Lopes CWG. Co-infection by Tritrichomonas foetus and Pentatrichomonas hominis in asymptomatic cats. Pesq Vet Bras 2015; 35(12): 980-988. http://dx.doi.org/10.1590/S0100-736X2015001200007.
http://dx.doi.org/10.1590/S0100-736X201...
found a prevalence of 5.2% of different-aged cats with diarrhea, using culture and PCR. In São Paulo, Hora et al. (2017) Hora AS, Miyashiro SI, Cassiano FC, Brandão PE, Reche-Junior A, Pena HFJ. Report of the first clinical case of intestinal trichomoniasis caused by Tritrichomonas foetus in a cat with chronic diarrhoea in Brazil. BMC Vet Res 2017; 13(1): 109. http://dx.doi.org/10.1186/s12917-017-1026-3. PMid:28412947.
http://dx.doi.org/10.1186/s12917-017-10...
described a clinical case of T. foetus infection in a chronic diarrheic 7-month-old cat and Duarte et al. (2018) Duarte RP, Rocha PRDA, Nakamura AA, Cipriano RS, Viol MA, Melo GD, et al. Detection of natural occurrence of Tritrichomonas foetus in cats in Araçatuba, São Paulo, Brazil. Pesq Vet Bras 2018; 38(2): 309-314. http://dx.doi.org/10.1590/1678-5150-pvb-5115.
http://dx.doi.org/10.1590/1678-5150-pvb...
observed five infected cats (3.6%).

In summary, the global prevalence of T. foetus infection in domestic cats, with and without diarrhea, ranges from 0-81.8%, according to the number of samples analyzed, the diagnostic method used, geographical region, and lifestyle of the cat population ( Table 1 ).

Table 1
Prevalence of Tritrichomonas foetus infection in domestic cats, according to the country, fecal sample source, and diagnostic method used.

Pathogenesis

Because it is a recently described parasite, the pathogenesis of T. foetus infection in cats is still not fully understood ( TOLBERT & GOOKIN, 2016 Tolbert MK, Gookin JL. Mechanisms of Tritrichomonas foetus Pathogenicity in Cats with Insights from Venereal Trichomonosis. J Vet Intern Med 2016; 30(2): 516-526. http://dx.doi.org/10.1111/jvim.13920. PMid:26946069.
http://dx.doi.org/10.1111/jvim.13920 ...
). There are hypotheses on whether the parasite alone could cause clinical signs, or whether feline trichomonosis could be a multifactorial disease, associated with enteric coinfections and host-related factors ( GOOKIN et al., 2004 Gookin JL, Stebbins ME, Hunt E, Burlone K, Fulton M, Hochel R, et al. Prevalence of and risk factors for feline Tritrichomonas foetus and Giardia infection. J Clin Microbiol 2004; 42(6): 2707-2710. http://dx.doi.org/10.1128/JCM.42.6.2707-2710.2004. PMid:15184456.
http://dx.doi.org/10.1128/JCM.42.6.2707...
).

T. foetus colonizes the ileum, cecum and colon of cats ( GOOKIN et al., 2001 Gookin JL, Levy MG, Law JM, Papich MG, Poore MF, Breitschwerdt EB. Experimental infection of cats with Tritrichomonas foetus. Am J Vet Res 2001; 62(11): 1690-1697. http://dx.doi.org/10.2460/ajvr.2001.62.1690. PMid:11703009.
http://dx.doi.org/10.2460/ajvr.2001.62....
; STOCKDALE et al., 2008 Stockdale HD, Dillon AR, Newton JC, Bird RC, Bondurant RH, Deinnocentes P, et al. Experimental infection of cats (Felis catus) with Tritrichomonas foetus isolated from cattle. Vet Parasitol 2008; 154(1-2): 156-161. http://dx.doi.org/10.1016/j.vetpar.2008.02.024. PMid:18394809.
http://dx.doi.org/10.1016/j.vetpar.2008...
). Experimental works demonstrated the cytotoxic and proteolytic activity of T. foetus to mammalian cells ( BURGESS & MCDONALD, 1992 Burgess DE, McDonald CM. Analysis of adhesion and cytotoxicity of Tritrichomonas foetus to mammalian cells by use of monoclonal antibodies. Infect Immun 1992; 60(10): 4253-4259. PMid:1398936. ). Infection is characterized by moderate lymphoplasmacytic and neutrophilic infiltration of the propria lamina ( YAEGER & GOOKIN, 2005 Yaeger MJ, Gookin JL. Histologic features associated with Tritrichomonas foetus induced colitis in domestic cats. Vet Pathol 2005; 42(6): 797-804. http://dx.doi.org/10.1354/vp.42-6-797. PMid:16301576.
http://dx.doi.org/10.1354/vp.42-6-797 ...
). A reduced colonic epithelium, cryptic hypertrophy, hyperplasia and increased mitotic activity, loss of goblet cells, and microabscesses in crypts have been described ( SCHREY et al., 2009 Schrey C, Mundhenk L, Gruber A, Henning K, Frey C. Tritrichomonas foetus as a cause of diarrhoea in three cats. Kleintierpraxis 2009; 54(2): 93-96. ). Eosinophilic inflammation can also occasionally be observed ( YAEGER & GOOKIN, 2005 Yaeger MJ, Gookin JL. Histologic features associated with Tritrichomonas foetus induced colitis in domestic cats. Vet Pathol 2005; 42(6): 797-804. http://dx.doi.org/10.1354/vp.42-6-797. PMid:16301576.
http://dx.doi.org/10.1354/vp.42-6-797 ...
; SCHREY et al., 2009 Schrey C, Mundhenk L, Gruber A, Henning K, Frey C. Tritrichomonas foetus as a cause of diarrhoea in three cats. Kleintierpraxis 2009; 54(2): 93-96. ).

Some factors suggest that bacteria present in the colon are an important part of the pathogenesis of diarrhea in cats infected with T. foetus. For example, diarrhea in these animals is usually slowed down with the administration of antibiotics ( GOOKIN et al., 1999 Gookin JL, Breitschwerdt EB, Levy MG, Gager RB, Benrud JG. Diarrhea associated with trichomonosis in cats. J Am Vet Med Assoc 1999; 215(10): 1450-1454. PMid:10579040. , 2001 Gookin JL, Levy MG, Law JM, Papich MG, Poore MF, Breitschwerdt EB. Experimental infection of cats with Tritrichomonas foetus. Am J Vet Res 2001; 62(11): 1690-1697. http://dx.doi.org/10.2460/ajvr.2001.62.1690. PMid:11703009.
http://dx.doi.org/10.2460/ajvr.2001.62....
). If these antibiotics directly reduce the bacterial contribution in the pathogenesis of diarrhea or simply reduce the numbers of T. foetus by nutrient support depletion is unknown ( TOLBERT & GOOKIN, 2016 Tolbert MK, Gookin JL. Mechanisms of Tritrichomonas foetus Pathogenicity in Cats with Insights from Venereal Trichomonosis. J Vet Intern Med 2016; 30(2): 516-526. http://dx.doi.org/10.1111/jvim.13920. PMid:26946069.
http://dx.doi.org/10.1111/jvim.13920 ...
).

Chronically infected cats may show extensive periods of clinical remission, but relapsing episodes of diarrhea may be triggered by dietary changes or stressful events that could change the colonic microbiota ( FOSTER et al., 2004 Foster DM, Gookin JL, Poore MF, Stebbins ME, Levy MG. Outcome of cats with diarrhea and Tritrichomonas foetus infection. J Am Vet Med Assoc 2004; 225(6): 888-892. http://dx.doi.org/10.2460/javma.2004.225.888. PMid:15485048.
http://dx.doi.org/10.2460/javma.2004.22...
).

Clinical Signals

The clinical signals vary from subclinical to severe cases of intestinal disease ( FOSTER et al., 2004 Foster DM, Gookin JL, Poore MF, Stebbins ME, Levy MG. Outcome of cats with diarrhea and Tritrichomonas foetus infection. J Am Vet Med Assoc 2004; 225(6): 888-892. http://dx.doi.org/10.2460/javma.2004.225.888. PMid:15485048.
http://dx.doi.org/10.2460/javma.2004.22...
). Experimentally, the signs appeared 2-7 days after oral ingestion ( GOOKIN et al., 2001 Gookin JL, Levy MG, Law JM, Papich MG, Poore MF, Breitschwerdt EB. Experimental infection of cats with Tritrichomonas foetus. Am J Vet Res 2001; 62(11): 1690-1697. http://dx.doi.org/10.2460/ajvr.2001.62.1690. PMid:11703009.
http://dx.doi.org/10.2460/ajvr.2001.62....
). Clinical signs include chronic or intermittent diarrhea, yellowish-green and malodorous stools, characteristics of colitis, which may include the presence of live blood, mucus, fecal incontinence, tenesmus, and/or flatulence ( GOOKIN et al., 2001 Gookin JL, Levy MG, Law JM, Papich MG, Poore MF, Breitschwerdt EB. Experimental infection of cats with Tritrichomonas foetus. Am J Vet Res 2001; 62(11): 1690-1697. http://dx.doi.org/10.2460/ajvr.2001.62.1690. PMid:11703009.
http://dx.doi.org/10.2460/ajvr.2001.62....
; XENOULIS et al., 2013 Xenoulis PG, Lopinski DJ, Read SA, Suchodolski JS, Steiner JM. Intestinal Tritrichomonas foetus infection in cats: a retrospective study of 104 cases. J Feline Med Surg 2013; 15(12): 1098-1103. http://dx.doi.org/10.1177/1098612X13495024. PMid:23838083.
http://dx.doi.org/10.1177/1098612X13495...
). Fecal consistency usually ranges from semi-formed to liquid ( SCHREY et al., 2009 Schrey C, Mundhenk L, Gruber A, Henning K, Frey C. Tritrichomonas foetus as a cause of diarrhoea in three cats. Kleintierpraxis 2009; 54(2): 93-96. ; XENOULIS et al., 2010 Xenoulis PG, Saridomichelakis MN, Read SA, Suchodolski JS, Steiner JM. Detection of Tritrichomonas foetus in cats in Greece. J Feline Med Surg 2010; 12(10): 831-833. http://dx.doi.org/10.1016/j.jfms.2010.05.010. PMid:20674428.
http://dx.doi.org/10.1016/j.jfms.2010.0...
). More severe cases may include marked inflammation in the anal region and rectal prolapse ( FOSTER et al., 2004 Foster DM, Gookin JL, Poore MF, Stebbins ME, Levy MG. Outcome of cats with diarrhea and Tritrichomonas foetus infection. J Am Vet Med Assoc 2004; 225(6): 888-892. http://dx.doi.org/10.2460/javma.2004.225.888. PMid:15485048.
http://dx.doi.org/10.2460/javma.2004.22...
; BURGENER et al., 2009 Burgener I, Frey CF, Kook P, Gottstein B. Tritrichomonas foetus: a new intestinal parasite in Swiss cats. Schweiz Arch Tierheilkd 2009; 151(8): 383-389. http://dx.doi.org/10.1024/0036-7281.151.8.383. PMid:19653162.
http://dx.doi.org/10.1024/0036-7281.151...
).

As expected in a disease that usually affects the large intestine, most infected cats have good body conditions, with no systemic signs ( GOOKIN et al., 1999 Gookin JL, Breitschwerdt EB, Levy MG, Gager RB, Benrud JG. Diarrhea associated with trichomonosis in cats. J Am Vet Med Assoc 1999; 215(10): 1450-1454. PMid:10579040. , 2001 Gookin JL, Levy MG, Law JM, Papich MG, Poore MF, Breitschwerdt EB. Experimental infection of cats with Tritrichomonas foetus. Am J Vet Res 2001; 62(11): 1690-1697. http://dx.doi.org/10.2460/ajvr.2001.62.1690. PMid:11703009.
http://dx.doi.org/10.2460/ajvr.2001.62....
; TOLBERT & GOOKIN 2009 Tolbert MK, Gookin JL. Tritrichomonas foetus: A new agent of feline diarrhea. Compend Contin Educ Vet 2009; 31(8): 374-381, 390, quiz 381. PMid:19866444. ), although one-fifth of infected cats can show systemic signs, such as anorexia, depression, weight loss, vomiting, and fever ( STOCKDALE et al., 2007 Stockdale H, Rodning S, Givens M, Carpenter D, Lenz S, Spencer J, et al. Experimental infection of cattle with a feline isolate of Tritrichomonas foetus. J Parasitol 2007; 93(6): 1429-1434. http://dx.doi.org/10.1645/GE-1305.1. PMid:18314690.
http://dx.doi.org/10.1645/GE-1305.1 ...
).

Clinical signs last from 5-24 months, averaging 9 months after diagnosis ( FOSTER et al., 2004 Foster DM, Gookin JL, Poore MF, Stebbins ME, Levy MG. Outcome of cats with diarrhea and Tritrichomonas foetus infection. J Am Vet Med Assoc 2004; 225(6): 888-892. http://dx.doi.org/10.2460/javma.2004.225.888. PMid:15485048.
http://dx.doi.org/10.2460/javma.2004.22...
). The severity of clinical signs varies, ranging from asymptomatic cases to intractable diarrhea ( FOSTER et al., 2004 Foster DM, Gookin JL, Poore MF, Stebbins ME, Levy MG. Outcome of cats with diarrhea and Tritrichomonas foetus infection. J Am Vet Med Assoc 2004; 225(6): 888-892. http://dx.doi.org/10.2460/javma.2004.225.888. PMid:15485048.
http://dx.doi.org/10.2460/javma.2004.22...
; GRAY et al., 2010 Gray SG, Hunter AS, Stone MR, Gookin JL. Assessment of reproductive tract disease in cats at risk for Tritrichomonas foetus infection. Am J Vet Res 2010; 71(1): 76-81. http://dx.doi.org/10.2460/ajvr.71.1.76. PMid:20043785.
http://dx.doi.org/10.2460/ajvr.71.1.76 ...
; XENOULIS et al., 2010 Xenoulis PG, Saridomichelakis MN, Read SA, Suchodolski JS, Steiner JM. Detection of Tritrichomonas foetus in cats in Greece. J Feline Med Surg 2010; 12(10): 831-833. http://dx.doi.org/10.1016/j.jfms.2010.05.010. PMid:20674428.
http://dx.doi.org/10.1016/j.jfms.2010.0...
).

Diagnostic Tools

Once the parasite only has the trophozoite phase, it cannot be identified in routine coproparasitological techniques and does not survive refrigeration. Therefore, the diagnosis of T. foetus infection requires more specific procedures ( GOOKIN et al., 1999 Gookin JL, Breitschwerdt EB, Levy MG, Gager RB, Benrud JG. Diarrhea associated with trichomonosis in cats. J Am Vet Med Assoc 1999; 215(10): 1450-1454. PMid:10579040. ).

Diagnosis can be made by direct examination of fresh feces smear ( GOOKIN et al., 1999 Gookin JL, Breitschwerdt EB, Levy MG, Gager RB, Benrud JG. Diarrhea associated with trichomonosis in cats. J Am Vet Med Assoc 1999; 215(10): 1450-1454. PMid:10579040. ), fecal culture using specific media ( GOOKIN et al., 2003 Gookin JL, Foster DM, Poore MF, Stebbins ME, Levy MG. Use of a commercially available culture system for diagnosis of Tritrichomonas foetus infection in cats. J Am Vet Med Assoc 2003; 222(10): 1376-1379. http://dx.doi.org/10.2460/javma.2003.222.1376. PMid:12762381.
http://dx.doi.org/10.2460/javma.2003.22...
), or PCR amplification ( GOOKIN et al., 2002 Gookin JL, Birkenheuer AJ, Breitschwerdt EB, Levy MG. Single-tube nested PCR for diagnosis of Tritrichomonas foetus in feline feces. J Vet Clin Microbiol 2002; 40(11): 4126-4130. http://dx.doi.org/10.1128/JCM.40.11.4126-4130.2002. PMid:12409385.
http://dx.doi.org/10.1128/JCM.40.11.412...
), which is the most widely used method in the literature. In addition, the parasite can be identified via histopathologic analysis of intestinal biopsies ( GOOKIN et al., 2001 Gookin JL, Levy MG, Law JM, Papich MG, Poore MF, Breitschwerdt EB. Experimental infection of cats with Tritrichomonas foetus. Am J Vet Res 2001; 62(11): 1690-1697. http://dx.doi.org/10.2460/ajvr.2001.62.1690. PMid:11703009.
http://dx.doi.org/10.2460/ajvr.2001.62....
; YAEGER & GOOKIN, 2005 Yaeger MJ, Gookin JL. Histologic features associated with Tritrichomonas foetus induced colitis in domestic cats. Vet Pathol 2005; 42(6): 797-804. http://dx.doi.org/10.1354/vp.42-6-797. PMid:16301576.
http://dx.doi.org/10.1354/vp.42-6-797 ...
).

Suitable fecal samples include either a freshly voided stool or collected by manual extraction with the aid of a fecal loop or by a colon flush technique, in which approximately 10 ml of sterile saline is injected through a catheter into the colon and then aspirated ( TOLBERT & GOOKIN, 2009 Tolbert MK, Gookin JL. Tritrichomonas foetus: A new agent of feline diarrhea. Compend Contin Educ Vet 2009; 31(8): 374-381, 390, quiz 381. PMid:19866444. ; YAO & KOSTER, 2015 Yao C, Koster LS. Tritrichomonas foetus infection, a cause of chronic diarrhea in the domestic cat. Vet Res 2015; 46(1): 35. http://dx.doi.org/10.1186/s13567-015-0169-0. PMid:25880025.
http://dx.doi.org/10.1186/s13567-015-01...
).

Fecal samples should be fresh, free of contaminating litter, and kept unrefrigerated before testing ( TOLBERT & GOOKIN, 2009 Tolbert MK, Gookin JL. Tritrichomonas foetus: A new agent of feline diarrhea. Compend Contin Educ Vet 2009; 31(8): 374-381, 390, quiz 381. PMid:19866444. ). To maximize the sensitivity of the direct examination and culture, feces should be analyzed within a 6-hour period after collection ( HALE et al., 2009 Hale S, Norris JM, Slapeta J. Prolonged resilience of Tritrichomonas foetus in cat faeces at ambient temperature. Vet Parasitol 2009; 166(1-2): 60-65. http://dx.doi.org/10.1016/j.vetpar.2009.07.032. PMid:19683398.
http://dx.doi.org/10.1016/j.vetpar.2009...
).

Diagnostic methods require the presence of parasite trophozoites in the feces. Fluctuations in the release of trophozoites are characteristic of venereal trichomonosis in cattle ( SKIRROW et al., 1985 Skirrow S, BonDurant R, Farley J, Correa J. Efficacy of ipronidazole against trichomoniasis in beef bulls. J Am Vet Med Assoc 1985; 187(4): 405-407. PMid:4030475. ). Similarly, in cats, the elimination of trophozoites in feces is probably intermittent ( GOOKIN et al., 2001 Gookin JL, Levy MG, Law JM, Papich MG, Poore MF, Breitschwerdt EB. Experimental infection of cats with Tritrichomonas foetus. Am J Vet Res 2001; 62(11): 1690-1697. http://dx.doi.org/10.2460/ajvr.2001.62.1690. PMid:11703009.
http://dx.doi.org/10.2460/ajvr.2001.62....
; STOCKDALE et al., 2008 Stockdale HD, Dillon AR, Newton JC, Bird RC, Bondurant RH, Deinnocentes P, et al. Experimental infection of cats (Felis catus) with Tritrichomonas foetus isolated from cattle. Vet Parasitol 2008; 154(1-2): 156-161. http://dx.doi.org/10.1016/j.vetpar.2008.02.024. PMid:18394809.
http://dx.doi.org/10.1016/j.vetpar.2008...
; HALE et al., 2009 Hale S, Norris JM, Slapeta J. Prolonged resilience of Tritrichomonas foetus in cat faeces at ambient temperature. Vet Parasitol 2009; 166(1-2): 60-65. http://dx.doi.org/10.1016/j.vetpar.2009.07.032. PMid:19683398.
http://dx.doi.org/10.1016/j.vetpar.2009...
), and can be reduced by recent antibiotic therapy ( GOOKIN et al., 1999 Gookin JL, Breitschwerdt EB, Levy MG, Gager RB, Benrud JG. Diarrhea associated with trichomonosis in cats. J Am Vet Med Assoc 1999; 215(10): 1450-1454. PMid:10579040. ; FOSTER et al., 2004 Foster DM, Gookin JL, Poore MF, Stebbins ME, Levy MG. Outcome of cats with diarrhea and Tritrichomonas foetus infection. J Am Vet Med Assoc 2004; 225(6): 888-892. http://dx.doi.org/10.2460/javma.2004.225.888. PMid:15485048.
http://dx.doi.org/10.2460/javma.2004.22...
; TOLBERT & GOOKIN, 2009 Tolbert MK, Gookin JL. Tritrichomonas foetus: A new agent of feline diarrhea. Compend Contin Educ Vet 2009; 31(8): 374-381, 390, quiz 381. PMid:19866444. ).

Direct fecal exam

The identification of motile trophozoites present in a fecal sample diluted with saline by direct examination using 200× or 400× optical microscopy is a simple and inexpensive means to detect T. foetus in feline feces. However, this test has low specificity and sensitivity ( HALE et al., 2009 Hale S, Norris JM, Slapeta J. Prolonged resilience of Tritrichomonas foetus in cat faeces at ambient temperature. Vet Parasitol 2009; 166(1-2): 60-65. http://dx.doi.org/10.1016/j.vetpar.2009.07.032. PMid:19683398.
http://dx.doi.org/10.1016/j.vetpar.2009...
).

The sensitivity of the technique is low because it depends on the presence of a large number of viable trophozoites in the fecal sample ( HALE et al., 2009 Hale S, Norris JM, Slapeta J. Prolonged resilience of Tritrichomonas foetus in cat faeces at ambient temperature. Vet Parasitol 2009; 166(1-2): 60-65. http://dx.doi.org/10.1016/j.vetpar.2009.07.032. PMid:19683398.
http://dx.doi.org/10.1016/j.vetpar.2009...
), and was below 2% in experimentally infected cats ( GOOKIN et al., 2001 Gookin JL, Levy MG, Law JM, Papich MG, Poore MF, Breitschwerdt EB. Experimental infection of cats with Tritrichomonas foetus. Am J Vet Res 2001; 62(11): 1690-1697. http://dx.doi.org/10.2460/ajvr.2001.62.1690. PMid:11703009.
http://dx.doi.org/10.2460/ajvr.2001.62....
, 2003 Gookin JL, Foster DM, Poore MF, Stebbins ME, Levy MG. Use of a commercially available culture system for diagnosis of Tritrichomonas foetus infection in cats. J Am Vet Med Assoc 2003; 222(10): 1376-1379. http://dx.doi.org/10.2460/javma.2003.222.1376. PMid:12762381.
http://dx.doi.org/10.2460/javma.2003.22...
) and 4% in naturally infected cats ( GOOKIN et al., 2003 Gookin JL, Foster DM, Poore MF, Stebbins ME, Levy MG. Use of a commercially available culture system for diagnosis of Tritrichomonas foetus infection in cats. J Am Vet Med Assoc 2003; 222(10): 1376-1379. http://dx.doi.org/10.2460/javma.2003.222.1376. PMid:12762381.
http://dx.doi.org/10.2460/javma.2003.22...
, 2004 Gookin JL, Stebbins ME, Hunt E, Burlone K, Fulton M, Hochel R, et al. Prevalence of and risk factors for feline Tritrichomonas foetus and Giardia infection. J Clin Microbiol 2004; 42(6): 2707-2710. http://dx.doi.org/10.1128/JCM.42.6.2707-2710.2004. PMid:15184456.
http://dx.doi.org/10.1128/JCM.42.6.2707...
). Detection can be optimized by using fresh, non-refrigerated, and diarrheal stools and performing multiple test analyses ( GOOKIN et al., 2001 Gookin JL, Levy MG, Law JM, Papich MG, Poore MF, Breitschwerdt EB. Experimental infection of cats with Tritrichomonas foetus. Am J Vet Res 2001; 62(11): 1690-1697. http://dx.doi.org/10.2460/ajvr.2001.62.1690. PMid:11703009.
http://dx.doi.org/10.2460/ajvr.2001.62....
, 2004 Gookin JL, Stebbins ME, Hunt E, Burlone K, Fulton M, Hochel R, et al. Prevalence of and risk factors for feline Tritrichomonas foetus and Giardia infection. J Clin Microbiol 2004; 42(6): 2707-2710. http://dx.doi.org/10.1128/JCM.42.6.2707-2710.2004. PMid:15184456.
http://dx.doi.org/10.1128/JCM.42.6.2707...
).

The specificity of the exam depends on the professional, who must be trained to differentiate T. foetus from other protozoan trophozoites, such as Giardia sp. ( GOOKIN et al., 2003 Gookin JL, Foster DM, Poore MF, Stebbins ME, Levy MG. Use of a commercially available culture system for diagnosis of Tritrichomonas foetus infection in cats. J Am Vet Med Assoc 2003; 222(10): 1376-1379. http://dx.doi.org/10.2460/javma.2003.222.1376. PMid:12762381.
http://dx.doi.org/10.2460/javma.2003.22...
). The trophozoites of T. foetus are pear shaped and have three anterior flagella, one nucleus, and an undulating membrane. The trophozoites of Giardia sp. have no undulating membrane, two nuclei, and one ventral disc. Trophozoites of T. foetus and Giardia sp. have the same size but move differently. The trophozoites of Giardia sp. have a falling leaf-like motility, while those of T. foetus move progressively ( GOOKIN et al., 2004 Gookin JL, Stebbins ME, Hunt E, Burlone K, Fulton M, Hochel R, et al. Prevalence of and risk factors for feline Tritrichomonas foetus and Giardia infection. J Clin Microbiol 2004; 42(6): 2707-2710. http://dx.doi.org/10.1128/JCM.42.6.2707-2710.2004. PMid:15184456.
http://dx.doi.org/10.1128/JCM.42.6.2707...
).

T. foetus and P. hominis cannot be easily distinguished morphologically from each another by examining living specimens. P. hominis has five anterior flagella, but these flagella are difficult to enumerate in a moving trophozoite ( LEVY et al., 2003 Levy MG, Gookin JL, Poore M, Birkenheuer AJ, Dykstra MJ, Litaker RW. Tritrichomonas foetus and not Pentatrichomonas hominis is the etiologic agent of feline trichomonal diarrhea. J Parasitol 2003; 89(1): 99-104. http://dx.doi.org/10.1645/0022-3395(2003)089[0099:TFANPH]2.0.CO;2. PMid:12659310.
http://dx.doi.org/10.1645/0022-3395(200...
). Gookin et al. (2007) Gookin JL, Stauffer SH, Coccaro MR, Poore MF, Levy MG, Papich MG. Efficacy of tinidazole for treatment of cats experimentally infected with Tritrichomonas foetus. Am J Vet Res 2007; 68(10): 1085-1088. http://dx.doi.org/10.2460/ajvr.68.10.1085. PMid:17916015.
http://dx.doi.org/10.2460/ajvr.68.10.10...
argue that P. hominis infection does not appear to contribute to the failure to diagnose trichomonosis, since P. hominis infection would always be accompanied by T. foetus, but the reverse is not true. Ceplecha et al. (2013) Ceplecha V, Svoboda M, Cepicka I, Husnik R, Horackova K, Svobodova V. InPouchTM TF-Feline medium is not specific for Tritrichomonas foetus. Vet Parasitol 2013; 196(3-4): 503-505. http://dx.doi.org/10.1016/j.vetpar.2013.04.015. PMid:23643452.
http://dx.doi.org/10.1016/j.vetpar.2013...
disagreed, and affirmed that the survival of P. hominis in fecal stools is a factor to be considered. According to them, confirmation of the true agent by molecular techniques is important to avoid the unnecessary use of ronidazole, the treatment of choice for feline trichomonosis, which has neurotoxic potential.

Fecal culture

Fecal culture is a sensitive and specific method for the diagnosis of T. foetus infection in cats ( GOOKIN et al., 2003 Gookin JL, Foster DM, Poore MF, Stebbins ME, Levy MG. Use of a commercially available culture system for diagnosis of Tritrichomonas foetus infection in cats. J Am Vet Med Assoc 2003; 222(10): 1376-1379. http://dx.doi.org/10.2460/javma.2003.222.1376. PMid:12762381.
http://dx.doi.org/10.2460/javma.2003.22...
). Two culture media are most commonly used and validated for parasite growth. The 'In Pouch TM TF – Feline’ culture pouch system (Biomed Diagnostics, White City, Oregon, USA) is an easy-to-use commercial test that can be performed within veterinary clinics because of its practicality. This pouch can be incubated at 37 °C or room temperature (23-24 °C), but the trichomonads multiply quickly at 37 °C ( GOOKIN et al., 2004 Gookin JL, Stebbins ME, Hunt E, Burlone K, Fulton M, Hochel R, et al. Prevalence of and risk factors for feline Tritrichomonas foetus and Giardia infection. J Clin Microbiol 2004; 42(6): 2707-2710. http://dx.doi.org/10.1128/JCM.42.6.2707-2710.2004. PMid:15184456.
http://dx.doi.org/10.1128/JCM.42.6.2707...
). In Pouch culture systems inoculated with more than 0.1 g of cat feces, led to overgrowth of gas-producing bacteria or yeast within 24 hours, which inhibited its usefulness for diagnosis ( GOOKIN et al., 2003 Gookin JL, Foster DM, Poore MF, Stebbins ME, Levy MG. Use of a commercially available culture system for diagnosis of Tritrichomonas foetus infection in cats. J Am Vet Med Assoc 2003; 222(10): 1376-1379. http://dx.doi.org/10.2460/javma.2003.222.1376. PMid:12762381.
http://dx.doi.org/10.2460/javma.2003.22...
). The other medium is modified Diamond’s medium that is enriched with nutrients and antibiotics, which requires sterilization and incubation at 37 °C ( GOOKIN et al., 2004 Gookin JL, Stebbins ME, Hunt E, Burlone K, Fulton M, Hochel R, et al. Prevalence of and risk factors for feline Tritrichomonas foetus and Giardia infection. J Clin Microbiol 2004; 42(6): 2707-2710. http://dx.doi.org/10.1128/JCM.42.6.2707-2710.2004. PMid:15184456.
http://dx.doi.org/10.1128/JCM.42.6.2707...
). The culture is examined under optical microscopy from days 2-12 after incubation, to identify mobile trophozoites. It may take up to 7 days for the organism to become detectable ( GOOKIN et al., 2003 Gookin JL, Foster DM, Poore MF, Stebbins ME, Levy MG. Use of a commercially available culture system for diagnosis of Tritrichomonas foetus infection in cats. J Am Vet Med Assoc 2003; 222(10): 1376-1379. http://dx.doi.org/10.2460/javma.2003.222.1376. PMid:12762381.
http://dx.doi.org/10.2460/javma.2003.22...
).

Gookin et al. (2004) Gookin JL, Stebbins ME, Hunt E, Burlone K, Fulton M, Hochel R, et al. Prevalence of and risk factors for feline Tritrichomonas foetus and Giardia infection. J Clin Microbiol 2004; 42(6): 2707-2710. http://dx.doi.org/10.1128/JCM.42.6.2707-2710.2004. PMid:15184456.
http://dx.doi.org/10.1128/JCM.42.6.2707...
found no significant difference between the two culture media, while Hale et al. (2009) Hale S, Norris JM, Slapeta J. Prolonged resilience of Tritrichomonas foetus in cat faeces at ambient temperature. Vet Parasitol 2009; 166(1-2): 60-65. http://dx.doi.org/10.1016/j.vetpar.2009.07.032. PMid:19683398.
http://dx.doi.org/10.1016/j.vetpar.2009...
determined a sensitivity of 83% and 100% for the InPouchTM commercial test and the modified Diamond’s medium methods, respectively. The limitation of this diagnostic method is that it requires viable trophozoites. At low temperatures and desiccation, T. foetus may die. Researchers have shown that feces maintained at room temperature for up to 6 h represent a suitable material for diagnostic investigation through fecal culture ( HALE et al., 2009 Hale S, Norris JM, Slapeta J. Prolonged resilience of Tritrichomonas foetus in cat faeces at ambient temperature. Vet Parasitol 2009; 166(1-2): 60-65. http://dx.doi.org/10.1016/j.vetpar.2009.07.032. PMid:19683398.
http://dx.doi.org/10.1016/j.vetpar.2009...
). The addition of saline solution to the fecal is recommended if the sample is transported or stocked prior to culturing. In addition, the fecal sample should be free of sand, which could desiccate the sample and kill the parasite ( GOOKIN et al., 2003 Gookin JL, Foster DM, Poore MF, Stebbins ME, Levy MG. Use of a commercially available culture system for diagnosis of Tritrichomonas foetus infection in cats. J Am Vet Med Assoc 2003; 222(10): 1376-1379. http://dx.doi.org/10.2460/javma.2003.222.1376. PMid:12762381.
http://dx.doi.org/10.2460/javma.2003.22...
).

Polymerase Chain Reaction (PCR)

The PCR method is considered a specific and more sensitive detection method for T. foetus, since it does not require viable trophozoites ( GOOKIN et al., 2002 Gookin JL, Birkenheuer AJ, Breitschwerdt EB, Levy MG. Single-tube nested PCR for diagnosis of Tritrichomonas foetus in feline feces. J Vet Clin Microbiol 2002; 40(11): 4126-4130. http://dx.doi.org/10.1128/JCM.40.11.4126-4130.2002. PMid:12409385.
http://dx.doi.org/10.1128/JCM.40.11.412...
; VERMEULEN, 2009 Vermeulen BD. Tritrichomonas foetus in young cats with chronic diarrhoea: Comparison of different diagnostic methods [PhD Thesis]. Utrecht: Utrecht University; 2009. ). The solution of the fecal sample or culture can be sedimented in a centrifuge and submitted for PCR analysis ( TOLBERT & GOOKIN., 2009 Tolbert MK, Gookin JL. Tritrichomonas foetus: A new agent of feline diarrhea. Compend Contin Educ Vet 2009; 31(8): 374-381, 390, quiz 381. PMid:19866444. ). A study by Gookin et al. (2004) Gookin JL, Stebbins ME, Hunt E, Burlone K, Fulton M, Hochel R, et al. Prevalence of and risk factors for feline Tritrichomonas foetus and Giardia infection. J Clin Microbiol 2004; 42(6): 2707-2710. http://dx.doi.org/10.1128/JCM.42.6.2707-2710.2004. PMid:15184456.
http://dx.doi.org/10.1128/JCM.42.6.2707...
found a sensitivity of 94.4% (34/36). On the other hand, the high cost of the exam may be a prohibitive factor in many cases ( GOOKIN et al., 2004 Gookin JL, Stebbins ME, Hunt E, Burlone K, Fulton M, Hochel R, et al. Prevalence of and risk factors for feline Tritrichomonas foetus and Giardia infection. J Clin Microbiol 2004; 42(6): 2707-2710. http://dx.doi.org/10.1128/JCM.42.6.2707-2710.2004. PMid:15184456.
http://dx.doi.org/10.1128/JCM.42.6.2707...
).

A large variety of molecular protocols were developed for the detection of T. foetus in cattle and felines ( HO et al., 1994 Ho MS, Conrad PA, Conrad PJ, LeFebvre RB, Perez E, BonDurant RH. BonDurant RH. Detection of bovine trichomoniasis with a specific DNA probe and PCR amplification system. J Clin Microbiol 1994; 32(1): 98-104. PMid:8126211. ; FELLEISEN et al., 1998 Felleisen RS, Lambelet N, Bachmann P, Nicolet J, Muller N, Gottstein B. Detection of Tritrichomonas foetus by PCR and DNA enzyme immunoassay based on rRNA gene unit sequences. J Clin Microbiol 1998; 36(2): 513-519. PMid:9466768. ; GOOKIN et al., 2002 Gookin JL, Birkenheuer AJ, Breitschwerdt EB, Levy MG. Single-tube nested PCR for diagnosis of Tritrichomonas foetus in feline feces. J Vet Clin Microbiol 2002; 40(11): 4126-4130. http://dx.doi.org/10.1128/JCM.40.11.4126-4130.2002. PMid:12409385.
http://dx.doi.org/10.1128/JCM.40.11.412...
; BONDURANT et al., 2003 BonDurant RH, Campero CM, Anderson ML, Van Hoosear KA. Detection of Tritrichomonas foetus by polymerase chain reaction in cultured isolates, cervicovaginal mucus, and formalin-fixed tissues from infected heifers and fetuses. J Vet Diagn Invest 2003; 15(6): 579-584. http://dx.doi.org/10.1177/104063870301500613. PMid:14667024.
http://dx.doi.org/10.1177/1040638703015...
; GRAHN et al., 2005 Grahn RA, BonDurant RH, van Hoosear KA, Walker RL, Lyons LA. An improved molecular assay for Tritrichomonas foetus. Vet Parasitol 2005; 127(1): 33-41. http://dx.doi.org/10.1016/j.vetpar.2004.08.018. PMid:15619373.
http://dx.doi.org/10.1016/j.vetpar.2004...
). Many tests rely on amplification of the 5.8S rRNA gene sequences using ITS1 and ITS2, which are more conserved regions among isolates ( FELLEISEN, 1997 Felleisen RS. Comparative sequence analysis of 5.8S rRNA genes and internal transcribed spacer (ITS) regions of trichomonadid protozoa. Parasitology 1997; 115(Pt 2): 111-119. http://dx.doi.org/10.1017/S0031182097001212. PMid:10190167.
http://dx.doi.org/10.1017/S003118209700...
). The most-used technique is the nested PCR, where two primer pairs are used, TFR3 and TFR4 and TFITS-F and TFITS-R ( GOOKIN et al., 2002 Gookin JL, Birkenheuer AJ, Breitschwerdt EB, Levy MG. Single-tube nested PCR for diagnosis of Tritrichomonas foetus in feline feces. J Vet Clin Microbiol 2002; 40(11): 4126-4130. http://dx.doi.org/10.1128/JCM.40.11.4126-4130.2002. PMid:12409385.
http://dx.doi.org/10.1128/JCM.40.11.412...
). Several studies have shown that the rRNA gene sequence is highly conserved among T. foetus isolates, and is reliably different from those of other trichomonads ( GOOKIN et al., 2002 Gookin JL, Birkenheuer AJ, Breitschwerdt EB, Levy MG. Single-tube nested PCR for diagnosis of Tritrichomonas foetus in feline feces. J Vet Clin Microbiol 2002; 40(11): 4126-4130. http://dx.doi.org/10.1128/JCM.40.11.4126-4130.2002. PMid:12409385.
http://dx.doi.org/10.1128/JCM.40.11.412...
). Therefore, primers TFR3 and TFR4 were specially designed to amplify the 347 bp fragment of T. foetus DNA ( GOOKIN et al., 2002 Gookin JL, Birkenheuer AJ, Breitschwerdt EB, Levy MG. Single-tube nested PCR for diagnosis of Tritrichomonas foetus in feline feces. J Vet Clin Microbiol 2002; 40(11): 4126-4130. http://dx.doi.org/10.1128/JCM.40.11.4126-4130.2002. PMid:12409385.
http://dx.doi.org/10.1128/JCM.40.11.412...
). The second primer pair (TFITS-F and TFITS-R) amplifies a 208 bp fragment of the rRNA gene, which binds to the sequence amplified by the primer pair as previously described ( GOOKIN et al., 2003 Gookin JL, Foster DM, Poore MF, Stebbins ME, Levy MG. Use of a commercially available culture system for diagnosis of Tritrichomonas foetus infection in cats. J Am Vet Med Assoc 2003; 222(10): 1376-1379. http://dx.doi.org/10.2460/javma.2003.222.1376. PMid:12762381.
http://dx.doi.org/10.2460/javma.2003.22...
). The combined use of these pairs of primers (TFR3 and TFR4 with TFITS-F and TFITS-R) results in the detection of 50 parasites per gram of feces 90% of the time, and 500 parasites per gram of feces 100% of the time ( GOOKIN et al., 2002 Gookin JL, Birkenheuer AJ, Breitschwerdt EB, Levy MG. Single-tube nested PCR for diagnosis of Tritrichomonas foetus in feline feces. J Vet Clin Microbiol 2002; 40(11): 4126-4130. http://dx.doi.org/10.1128/JCM.40.11.4126-4130.2002. PMid:12409385.
http://dx.doi.org/10.1128/JCM.40.11.412...
). One such study showed that nested PCR (single tube) did not amplify the genomic DNA of feline isolates of Giardia sp. or P. hominis.

The reduced sensitivity of PCR for the detection of T. foetus in feces is due to the presence of inhibitors in feces, which are not found in other substances, such as blood. The composition of feces is biologically complex, dependent on the intestinal flora, diet, and concomitant diseases ( KATHER et al., 2007 Kather EJ, Marks SL, Kass PH. Determination of the in vitro susceptibility of feline Tritrichomonas foetus to 5 Antimicrobial agents. J Vet Intern Med 2007; 21(5): 966-970. http://dx.doi.org/10.1111/j.1939-1676.2007.tb03050.x. PMid:17939550.
http://dx.doi.org/10.1111/j.1939-1676.2...
). Fecal components, such as polysaccharide complexes, bile salts, hemoglobin degradation products, phenolic compounds, and heavy metals are generally co-extracted with the pathogen DNA and may interfere with the PCR ( GOOKIN et al., 2002 Gookin JL, Birkenheuer AJ, Breitschwerdt EB, Levy MG. Single-tube nested PCR for diagnosis of Tritrichomonas foetus in feline feces. J Vet Clin Microbiol 2002; 40(11): 4126-4130. http://dx.doi.org/10.1128/JCM.40.11.4126-4130.2002. PMid:12409385.
http://dx.doi.org/10.1128/JCM.40.11.412...
; STAUFFER et al., 2008 Stauffer SH, Birkenheuer AJ, Levy MG, Marr H, Gookin JL. Evaluation of four DNA extraction methods for the detection of Tritrichomonas foetus in feline stool specimens by polymerase chain reaction. J Vet Diagn Invest 2008; 20(5): 639-641. http://dx.doi.org/10.1177/104063870802000518. PMid:18776100.
http://dx.doi.org/10.1177/1040638708020...
). Presence of bacteria also interfere with T. foetus identification by PCR, as well as in the fecal culture ( CLOTHIER et al., 2015 Clothier KA, Villanueva M, Torain A, Hult C, Wallace R. Effects of bacterial contamination of media on the diagnosis of Tritrichomonas foetus by culture and real-time PCR. Vet Parasitol 2015; 208(3-4): 143-149. http://dx.doi.org/10.1016/j.vetpar.2015.01.006. PMid:25639514.
http://dx.doi.org/10.1016/j.vetpar.2015...
).

A DNA sample can be tested for the presence of inhibitors through a separate reaction, where bacterial 16S rRNA genes are amplified. If these genes cannot be amplified, PCR inhibitors are present in the fecal sample ( GOOKIN et al., 2006 Gookin JL, Copple CN, Papich MG, Poore MF, Stauffer SH, Birkenheuer AJ, et al. Efficacy of ronidazole for treatment of feline Tritrichomonas foetus infection. J Vet Intern Med 2006; 20(3): 536-543. http://dx.doi.org/10.1111/j.1939-1676.2006.tb02893.x. PMid:16734086.
http://dx.doi.org/10.1111/j.1939-1676.2...
). To minimize the false-negative results caused by the presence of inhibitors, there are techniques that optimize fecal material extraction, using proteinase K and temperature optimization, and the use of an additional washing step prior to DNA elution ( GOOKIN et al., 2002 Gookin JL, Birkenheuer AJ, Breitschwerdt EB, Levy MG. Single-tube nested PCR for diagnosis of Tritrichomonas foetus in feline feces. J Vet Clin Microbiol 2002; 40(11): 4126-4130. http://dx.doi.org/10.1128/JCM.40.11.4126-4130.2002. PMid:12409385.
http://dx.doi.org/10.1128/JCM.40.11.412...
).

Histopathology

The trophozoites of T. foetus can also be detected in the large intestine by histopathology, but their preservation in the biopsy specimens is difficult, because of its fragility. Yaeger and Gookin (2005) Yaeger MJ, Gookin JL. Histologic features associated with Tritrichomonas foetus induced colitis in domestic cats. Vet Pathol 2005; 42(6): 797-804. http://dx.doi.org/10.1354/vp.42-6-797. PMid:16301576.
http://dx.doi.org/10.1354/vp.42-6-797 ...
observed parasites in formalin-fixed colon tissues. Immunohistochemistry, fluorescence, and chromogenic in situ hybridization are techniques developed to localize and identify the parasite in tissue samples maintained in formalin, but are not commercially available ( GOOKIN et al., 2010 Gookin JL, Stone MR, Yaeger MJ, Meyerholz DK, Moisan P. Fluorescence in situ hybridization for identification of Tritrichomonas foetus in formalin-fixed and paraffin-embedded histological specimens of intestinal trichomoniasis. Vet Parasitol 2010; 172(1-2): 139-143. http://dx.doi.org/10.1016/j.vetpar.2010.04.014. PMid:20447769.
http://dx.doi.org/10.1016/j.vetpar.2010...
).

Treatment

The search for an effective and safe treatment for feline T. foetus infection is ongoing. The parasite demonstrated a poor sensitivity to several antimicrobial drugs, including metronidazole and tinidazole, drugs commonly used to treat intestinal protozoa and human vaginal trichomonosis ( GOOKIN et al., 1999 Gookin JL, Breitschwerdt EB, Levy MG, Gager RB, Benrud JG. Diarrhea associated with trichomonosis in cats. J Am Vet Med Assoc 1999; 215(10): 1450-1454. PMid:10579040. ; ROMATOWSKI, 2000 Romatowski J. Pentatrichomonas hominis infection in four kittens. J Am Vet Med Assoc 2000; 216(8): 1270-1272. http://dx.doi.org/10.2460/javma.2000.216.1270. PMid:10767968.
http://dx.doi.org/10.2460/javma.2000.21...
; GOOKIN et al., 2001 Gookin JL, Levy MG, Law JM, Papich MG, Poore MF, Breitschwerdt EB. Experimental infection of cats with Tritrichomonas foetus. Am J Vet Res 2001; 62(11): 1690-1697. http://dx.doi.org/10.2460/ajvr.2001.62.1690. PMid:11703009.
http://dx.doi.org/10.2460/ajvr.2001.62....
; KATHER et al., 2007 Kather EJ, Marks SL, Kass PH. Determination of the in vitro susceptibility of feline Tritrichomonas foetus to 5 Antimicrobial agents. J Vet Intern Med 2007; 21(5): 966-970. http://dx.doi.org/10.1111/j.1939-1676.2007.tb03050.x. PMid:17939550.
http://dx.doi.org/10.1111/j.1939-1676.2...
).

Ronidazole is currently the drug of choice for treatment ( GOOKIN et al., 2006 Gookin JL, Copple CN, Papich MG, Poore MF, Stauffer SH, Birkenheuer AJ, et al. Efficacy of ronidazole for treatment of feline Tritrichomonas foetus infection. J Vet Intern Med 2006; 20(3): 536-543. http://dx.doi.org/10.1111/j.1939-1676.2006.tb02893.x. PMid:16734086.
http://dx.doi.org/10.1111/j.1939-1676.2...
). The drug is rapidly absorbed into the proximal small intestine, metabolized, and eliminated by the liver and kidneys ( ROSADO et al., 2007 Rosado TW, Specht A, Marks SL. Neurotoxicosis in 4 cats receiving ronidazole. J Vet Intern Med 2007; 21(2): 328-331. http://dx.doi.org/10.1111/j.1939-1676.2007.tb02968.x. PMid:17427396.
http://dx.doi.org/10.1111/j.1939-1676.2...
; LEVINE et al., 2011 LeVine DN, Papich MG, Gookin JL, Davidson GS, Davis JL, Hayes RB. Ronidazole pharmacokinetics after intravenous and oral immediate-release capsule administration in healthy cats. J Feline Med Surg 2011; 13(4): 244-250. http://dx.doi.org/10.1016/j.jfms.2010.12.001. PMid:21239199.
http://dx.doi.org/10.1016/j.jfms.2010.1...
). The current recommended dose is 30 mg/kg once daily for a period of 14 days ( LEVINE et al., 2011 LeVine DN, Papich MG, Gookin JL, Davidson GS, Davis JL, Hayes RB. Ronidazole pharmacokinetics after intravenous and oral immediate-release capsule administration in healthy cats. J Feline Med Surg 2011; 13(4): 244-250. http://dx.doi.org/10.1016/j.jfms.2010.12.001. PMid:21239199.
http://dx.doi.org/10.1016/j.jfms.2010.1...
). High doses of ronidazole are associated with signs of neurotoxicity in cats, with changes occurring at least three days after treatment and ceasing within one to four weeks after discontinuation ( ROSADO et al., 2007 Rosado TW, Specht A, Marks SL. Neurotoxicosis in 4 cats receiving ronidazole. J Vet Intern Med 2007; 21(2): 328-331. http://dx.doi.org/10.1111/j.1939-1676.2007.tb02968.x. PMid:17427396.
http://dx.doi.org/10.1111/j.1939-1676.2...
). The neurotoxic effects are dose-dependent and can be attributed to the long half-life of the drug. Cats with neurotoxicity may exhibit loss of appetite, mental changes, lethargy, ataxia, facial tremors, hyperesthesia, weakness in the pelvic limbs, and occasionally convulsions ( LEVINE et al. 2011 LeVine DN, Papich MG, Gookin JL, Davidson GS, Davis JL, Hayes RB. Ronidazole pharmacokinetics after intravenous and oral immediate-release capsule administration in healthy cats. J Feline Med Surg 2011; 13(4): 244-250. http://dx.doi.org/10.1016/j.jfms.2010.12.001. PMid:21239199.
http://dx.doi.org/10.1016/j.jfms.2010.1...
). These cats may require intensive veterinary support until the side effects resolve ( ROSADO et al., 2007 Rosado TW, Specht A, Marks SL. Neurotoxicosis in 4 cats receiving ronidazole. J Vet Intern Med 2007; 21(2): 328-331. http://dx.doi.org/10.1111/j.1939-1676.2007.tb02968.x. PMid:17427396.
http://dx.doi.org/10.1111/j.1939-1676.2...
).

After administration of the drug, the consistency of the feces of the infected cats generally improves rapidly in days and normalizes after the treatment of two weeks ( GOOKIN et al., 2006 Gookin JL, Copple CN, Papich MG, Poore MF, Stauffer SH, Birkenheuer AJ, et al. Efficacy of ronidazole for treatment of feline Tritrichomonas foetus infection. J Vet Intern Med 2006; 20(3): 536-543. http://dx.doi.org/10.1111/j.1939-1676.2006.tb02893.x. PMid:16734086.
http://dx.doi.org/10.1111/j.1939-1676.2...
; BURGENER et al., 2009 Burgener I, Frey CF, Kook P, Gottstein B. Tritrichomonas foetus: a new intestinal parasite in Swiss cats. Schweiz Arch Tierheilkd 2009; 151(8): 383-389. http://dx.doi.org/10.1024/0036-7281.151.8.383. PMid:19653162.
http://dx.doi.org/10.1024/0036-7281.151...
; HOLLIDAY et al., 2009 Holliday M, Deni D, Gunn-Moore DA. Tritrichomonas foetus infection in cats with diarrhoea in a rescue colony in Italy. J Feline Med Surg 2009; 11(2): 131-134. http://dx.doi.org/10.1016/j.jfms.2008.06.004. PMid:18774326.
http://dx.doi.org/10.1016/j.jfms.2008.0...
; BELL et al., 2010 Bell ET, Gowan RA, Lingard AE, McCoy RJ, Slapeta J, Malik R. Naturally occurring Tritrichomonas foetus infections in Australian cats: 38 cases. J Feline Med Surg 2010; 12(12): 889-898. http://dx.doi.org/10.1016/j.jfms.2010.06.003. PMid:20817588.
http://dx.doi.org/10.1016/j.jfms.2010.0...
). In some cases of infected cats, diarrhea may not resolve for weeks after treatment due to severe colitis ( TOLBERT & GOOKIN, 2009 Tolbert MK, Gookin JL. Tritrichomonas foetus: A new agent of feline diarrhea. Compend Contin Educ Vet 2009; 31(8): 374-381, 390, quiz 381. PMid:19866444. ). Symptoms may return after treatment, since complete elimination of the parasite does not always occur ( BURGENER et al., 2009 Burgener I, Frey CF, Kook P, Gottstein B. Tritrichomonas foetus: a new intestinal parasite in Swiss cats. Schweiz Arch Tierheilkd 2009; 151(8): 383-389. http://dx.doi.org/10.1024/0036-7281.151.8.383. PMid:19653162.
http://dx.doi.org/10.1024/0036-7281.151...
; GOOKIN et al., 2010 Gookin JL, Stone MR, Yaeger MJ, Meyerholz DK, Moisan P. Fluorescence in situ hybridization for identification of Tritrichomonas foetus in formalin-fixed and paraffin-embedded histological specimens of intestinal trichomoniasis. Vet Parasitol 2010; 172(1-2): 139-143. http://dx.doi.org/10.1016/j.vetpar.2010.04.014. PMid:20447769.
http://dx.doi.org/10.1016/j.vetpar.2010...
). Infection usually resolves after repeated treatment ( GOOKIN et al., 2006 Gookin JL, Copple CN, Papich MG, Poore MF, Stauffer SH, Birkenheuer AJ, et al. Efficacy of ronidazole for treatment of feline Tritrichomonas foetus infection. J Vet Intern Med 2006; 20(3): 536-543. http://dx.doi.org/10.1111/j.1939-1676.2006.tb02893.x. PMid:16734086.
http://dx.doi.org/10.1111/j.1939-1676.2...
). Studies have shown that treatment with other drugs such as fenbendazole, paromomycin, tinidazole, metronidazole, and furazolidone improved the consistency of feces during the treatment period, but the parasite was not eradicated, so diarrhea returned when the medications ceased ( KATHER et al., 2007 Kather EJ, Marks SL, Kass PH. Determination of the in vitro susceptibility of feline Tritrichomonas foetus to 5 Antimicrobial agents. J Vet Intern Med 2007; 21(5): 966-970. http://dx.doi.org/10.1111/j.1939-1676.2007.tb03050.x. PMid:17939550.
http://dx.doi.org/10.1111/j.1939-1676.2...
).

Prognosis

The prognosis for feline T. foetus infection is good. After infection, many cats maintain themselves with normal physical condition. In 88% of cats with diarrhea, fecal consistency returns to normal spontaneously after 2 years of infection ( FOSTER et al., 2004 Foster DM, Gookin JL, Poore MF, Stebbins ME, Levy MG. Outcome of cats with diarrhea and Tritrichomonas foetus infection. J Am Vet Med Assoc 2004; 225(6): 888-892. http://dx.doi.org/10.2460/javma.2004.225.888. PMid:15485048.
http://dx.doi.org/10.2460/javma.2004.22...
).

The mean duration of diarrhea is 135 days ( XENOULIS et al., 2010 Xenoulis PG, Saridomichelakis MN, Read SA, Suchodolski JS, Steiner JM. Detection of Tritrichomonas foetus in cats in Greece. J Feline Med Surg 2010; 12(10): 831-833. http://dx.doi.org/10.1016/j.jfms.2010.05.010. PMid:20674428.
http://dx.doi.org/10.1016/j.jfms.2010.0...
). However, the spontaneous elimination of T. foetus is rare. Recurrent diarrhea associated with stress or changes in the intestinal flora are common ( FOSTER et al., 2004 Foster DM, Gookin JL, Poore MF, Stebbins ME, Levy MG. Outcome of cats with diarrhea and Tritrichomonas foetus infection. J Am Vet Med Assoc 2004; 225(6): 888-892. http://dx.doi.org/10.2460/javma.2004.225.888. PMid:15485048.
http://dx.doi.org/10.2460/javma.2004.22...
). In addition, studies reveal that chronic infection may predispose cats to develop inflammatory bowel disease ( GOOKIN et al., 2001 Gookin JL, Levy MG, Law JM, Papich MG, Poore MF, Breitschwerdt EB. Experimental infection of cats with Tritrichomonas foetus. Am J Vet Res 2001; 62(11): 1690-1697. http://dx.doi.org/10.2460/ajvr.2001.62.1690. PMid:11703009.
http://dx.doi.org/10.2460/ajvr.2001.62....
).

Prevention

Kittens or young animals raised in environments with agglomerations are more susceptible to infection due to stress or immune immaturity. Thus, minimizing stress and avoiding overpopulation would be important to reduce the chance of exposure to the agent and development of trichomonosis. As previously mentioned, the parasite is stable and viable in the environment for several days, which emphasizes the need for adequate disinfection of beds, transport boxes, litterboxes, and fomites ( HALE et al., 2009 Hale S, Norris JM, Slapeta J. Prolonged resilience of Tritrichomonas foetus in cat faeces at ambient temperature. Vet Parasitol 2009; 166(1-2): 60-65. http://dx.doi.org/10.1016/j.vetpar.2009.07.032. PMid:19683398.
http://dx.doi.org/10.1016/j.vetpar.2009...
).

Conclusion

Feline trichomonosis is a recent concern in veterinary medicine, caused by the parasite T. foetus. Infected cats can be asymptomatic or can present with chronic diarrhea. The diagnosis may be challenging as it demands more specific tests, such as fecal culture and PCR. Unfortunately, testing is still not routine in most veterinary clinics. Knowledge of this new emerging disease is important for the adequate parasite detection and treatment.

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Publication Dates

  • Publication in this collection
    11 Mar 2019
  • Date of issue
    Jan-Mar 2019

History

  • Received
    06 Sept 2018
  • Accepted
    29 Jan 2019
Colégio Brasileiro de Parasitologia Veterinária FCAV/UNESP - Departamento de Patologia Veterinária, Via de acesso Prof. Paulo Donato Castellane s/n, Zona Rural, , 14884-900 Jaboticabal - SP, Brasil, Fone: (16) 3209-7100 RAMAL 7934 - Jaboticabal - SP - Brazil
E-mail: cbpv_rbpv.fcav@unesp.br