Trichomonas tenax: A Neglected Protozoan Infection in the Oral Cavities of Humans and Dogs—A Scoping Review

Abstract

Trichomonas tenax is a flagellated protozoan parasite found in the oral cavities of humans and animals and has been associated with periodontal disease, the most prevalent inflammatory disease affecting them all. Studies have shown that T. tenax can cause damage to mammalian cells and secretes virulent proteins, such as cysteine. It is presently considered zoonotic. Despite the few studies that have been done, the pathogenicity of this oral protozoan is still not fully understood. A database search was performed in July 2022 using PubMed and Google Scholar to retrieve data eligible for this study. PRISMA-ScR guidelines were followed to conduct this scoping review. A total of 321 articles were found with 87 included in this review after applying the exclusion criteria. Due to its increasing prevalence worldwide in both humans and dogs, detecting and elucidating the pathogenicity of this parasite is paramount for effective global control and prevention of periodontal disease. However, there is a paucity in the literature on this neglected zoonotic trichomonad, which is in large contrast to the closely related human pathogen T. vaginalis. Here, we comprehensively review the history, morphology and reproduction, host, prevalence, diagnosis, pathogenicity, control, and prevention of T. tenax. Hopefully, this article will call attention to both medical and veterinary professionals as well as epidemiologists on this most neglected and zoonotic protozoan. More epidemiological and clinical studies need to be conducted on T. tenax to gain a better understanding of its pathogenicity, to increase the chances of developing effective drugs to aid in the control of this oral parasite, and reduce the spread of periodontal disease worldwide.

Molecular detection of oral Trichomonas tenax in periodontal disease patients by polymerase chain reaction -based 18S rRNA gene

“…The presence of T. tenax in periodontitis patients was higher than that in gingivitis patients, in accordance with results in other studies (Athari et al, 2007;Marty et al, 2017;Benabdelkader et al, 2019;Bracamonte-Wolf et al, 2019;Yaseen et al, 2021;Matthew et al, 2023). The explanation of the study's results could be supported by Ribeiro et al (2015) and Marty et al (2017), who revealed that the occurrence of T. tenax in the deep periodontal pocket may substantiate this role in periodontal dysbiosis.…”

Prevalence of Trichomonas tenax in the Population Affected by Periodontal Disease—A Review

“…The detection methods were unspecified in two studies and biochemical methods were used in one. We observed that many scientists have identified Trichomonas tenax through microscopic examination, with or without pre-staining, by visualizing pearshaped or elliptical cells with several flagella [91]. Microscopic examination was the primary detection method in forty studies, with thirty-nine using light microscopy and one employing phase-contrast microscopy.…”

Comparative genomics between Trichomonas tenax and Trichomonas vaginalis: CAZymes and candidate virulence factors

“…Similar to the closely related sexually transmitted parasite Trichomonas vaginalis , which is human-specific, T. tenax was also commonly considered to be specifically associated with humans (Honigberg, 1990 ; Maritz et al, 2014 ). However, the use of sensitive molecular diagnostic tools has clearly demonstrated that T. tenax is common in the oral cavity of a broader range of hosts including, cats, dogs and horses and with some additional reports among birds (Kellerová and Tachezy, 2017 ; Matthew et al, 2023 ). There are also reports of the isolation of T. tenax from extra-oral locations including the respiratory tract, lymph nodes, salivary glands and the urogenital tract (Maritz et al, 2014 ; Brosh-Nissimov et al, 2019 ).…”

“…However, the ability of T. tenax to contribute, directly or indirectly, to the pathobiology of periodontitis, is still poorly understood. Indeed, there is a lack of data on the molecular and cellular basis of T. tenax interactions with host cells (Matthew et al, 2023 ), members of the microbiota, and its potential endosymbionts, three key factors considered important in modulating the pathobiology of T. vaginalis (Hirt et al, 2011 ; Mercer and Johnson, 2018 ; Riestra et al, 2022 ; Margarita et al, 2023 ).…”

“…We focused our analyses to specifically test the hypothesis that T. tenax encodes a range of virulence and colonization factors that contribute directly and indirectly to the pathobiology of periodontitis through interaction with various host cells and members of the oral microbiota, as known for T. vaginalis (Hirt, 2013 ; Mercer and Johnson, 2018 ; Riestra et al, 2022 ). Indeed, only a handful of publications have investigated the potential virulence of T. tenax on host cells and the virulence factors that could be associated with the observed impact on host cells (reviewed in Matthew et al, 2023 ). Similarly, we are aware of only one study that has considered T. tenax genes encoding candidate proteins mediating interactions with members of the microbiota, i.e.…”