Periodontal diseases (gingivitis and periodontitis), result from a disruption of the host–oral microbiome homoeostasis. Whereas the pathological role of some specific bacterial strains during periodontal diseases is well documented, the impact of parasites in periodontium pathophysiology is still under debate. This review aims to collect data about the prevalence and the potential role of Trichomonas tenax during periodontal diseases. Data from 47 studies revealed that T. tenax prevalence in diseased periodontium ranged from 0 to 94·1%. The prevalence of oral protozoan infections was found to be largely greater in patients with periodontal diseases than with healthy periodontium. The parasite detection was mainly performed by direct microscopy. Trichomonas tenax presence was clearly correlated with periodontal disease. The high heterogeneity of its periodontal prevalence may be correlated with the diversity of the population screened (age, sex, systemic diseases), and the methods used for diagnosis. This protozoan seems to have the capacity to be involved in the inflammatory process of gum disease. Animal experimentation, using relevant physiopathological models of periodontitis, needs to be performed to investigate the ability of T. tenax to cause and/or worsen the disease. Further investigations using standardized experimental designs of epidemiologic studies are also needed.

The world health organization currently recognizes diarrhoeal diseases as a significant cause of death in children globally. Protozoan parasites such as Giardia and Entamoeba that thrive in the oxygen-deprived environment of the human gut are common etiological agents of diarrhoea. In the urogenital tract of humans, the anaerobic protozoan parasite Trichomonas vaginalis is notorious as the most common non-viral, sexually transmitted pathogen. Even with high medical impact, our understanding of anaerobic parasite physiology is scarce and as a result, treatment choices are limited. Fluorescent proteins (FPs) are invaluable tools as genetically encoded protein tags for advancing knowledge of cellular function. These FP tags emit fluorescent colours and once attached to a protein of interest, allow tracking of parasite proteins in the dynamic cellular space. Application of green FPs-like FPs in anaerobic protozoans is hindered by their oxygen dependency. In this review, we examine aspects of anaerobic parasite biology that clash with physio-chemical properties of FPs and limit their use as live-parasite protein tags. We expose novel FPs, such as miniSOG that do not require oxygen for signal production. The potential use of novel FPs has the opportunity to leverage the anaerobe parasitologist toolkit to that of aerobe parasitologist.

We used data from the Genitourinary Medicine Clinic Activity Dataset (GUMCAD) over a 3-year period (2009–2011) to investigate the distribution and risk factors of Trichomonas vaginalis infection in England. Socio-demographic and clinical risk factors associated with a diagnosis of T. vaginalis were explored using multivariable logistic regression. Rates of T. vaginalis infection were highest in London and the West Midlands. For men and women, T. vaginalis infection was significantly associated with: older age compared to those aged 20–24 years, non-white ethnicity (in particular black Caribbean and black ‘other’ ethnic groups), and birth in the Caribbean vs. birth in the UK. Current gonorrhoea or chlamydia infection was associated with a diagnosis of T. vaginalis in women. Further research is required to assess the public health impact and cost-effectiveness of introducing targeted screening for women at high risk of infection in areas of higher prevalence.

Thioredoxin reductase (TrxR), a NADPH-dependent disulfide oxidoreductase, is vital in numerous cellular processes including defence against reactive oxygen species, cell proliferation and signal transduction. TrxRs occur in 2 forms, a high Mr enzyme characterized by those of mammals, the malaria parasite Plasmodium falciparum and some worms, and a low Mr form is present in bacteria, fungi, plants and some protozoan parasites. Our hypothesis is that the differences between the forms can be exploited in the development of selective inhibitors. In this study, cyclodextrin- and sulfonic acid-derived organotelluriums known to inhibit mammalian TrxR were investigated for their relative efficacy against P. falciparum TrxR (PfTrxR), a high Mr enzyme, and Trichomonas vaginalis TrxR (TvTrxR), a low Mr form of TrxR. The results suggest that selective inhibition of low Mr TrxRs is a feasible goal.

The taxonomic situation in the genus Tritrichomonas is the subject of controversial discussion: potentially T. foetus and T. suis, the tritrichomonads from cattle and swine, respectively, could belong to the same species. In order to shed some light on this question, a molecular biological analysis was performed. The 5·8S rRNA gene and the flanking internal transcribed spacer regions (ITS1 and ITS2) of 12 different isolates of 3 Tritrichomonas species T. foetus, T. suis and T. mobilensis were enzymatically amplified by PCR and subcloned. Also, the corresponding regions of the trichomonads Trichomonas vaginalis, T. tenax, T. gallinae and Pentatrichomonas hominis were included in this study. Sequence analysis of cloned fragments was used to compare the parasite isolates. The genus Tritrichomonas exhibited an extremely high degree of homogeneity. All T. foetus and T. suis isolates had identical sequences, and only 1 substitution was found in the ITS2 region of T. mobilensis. In contrast, the genus Trichomonas shared more diversity. The results obtained in this study support a possible future revision of the taxonomic classification of tritrichomonads.