First evidence of previously undescribed trichomonad species in the intestine of pigs?

Trichomonosis in Austrian Songbirds—Geographic Distribution, Pathological Lesions and Genetic Characterization over Nine Years

In the early summer of 2012, sudden mass mortality among songbirds, particularly in greenfinches (Chloris chloris, syn: Carduelis chloris) was observed in Austria, which was caused by the protozoan parasite Trichomonas gallinae. This pathogen induced fibrinonecrotic ingluvitis and/or esophagitis, leading to impairment of food intake and ultimately death due to starvation. The pathogen was successfully detected within the lesions by polymerase chain reaction (PCR) and chromogenic in situ hybridization. The epizootic resulted in a significant decline in the Austrian greenfinch population. Continuing passive surveillance in the subsequent years (2013–2020) revealed that the condition occurred each year and was present in the entire country. Genetic characterization of the pathogen showed the presence of an identical strain irrespective of geographical location, bird species, and year.

MULTIPLE EPIDEMICS IN AUSTRIAN FRINGILLIDAE CAUSED BY A SINGLE VARIANT OF SALMONELLA TYPHIMURIUM

In Austria, numerous deaths of wild birds of the order Passeriformes, family Fringillidae, occurred during the winter months of 2010 and 2012. The Eurasian Siskin (Carduelis spinus) was the species most often affected. The dead birds were mainly found in the immediate vicinity of feeding places. Vigilant citizens sent birds (n=34) for pathologic examination to the Institute of Pathology in Vienna, Austria. All birds were cachectic or in a very poor nutritional condition. At gross examination, the most striking findings were multifocal to confluent, yellow-white nodules in the crop or esophageal mucosa. In histologically examined birds (n=24), severe transmural fibrino-purulent to necrotizing ingluviitis or esophagitis with large amounts of intralesional bacteria was observed. Bacteriologic examination of crop, liver, or other organs from 14 birds revealed abundant growth of Salmonella serovar Typhimurium (antigenic formula 1,4,5,12:i:1,2; phage type U277) in all individuals. By means of immunohistochemistry, these bacteria were detected not only in crop mucosa but also in lung tissue. In 17 birds (71%), structures morphologically resembling Macrorhabdus ornithogaster were detected histologically on the surface of the proventricular epithelium. Thus, the cause of mass mortality of the passerine birds was identified as infection with Salmonella Typhimurium, which was associated with growth of presumed M. ornithogaster in many cases.

Gut eukaryotic communities in pigs: diversity, composition and host genetics contribution

BACKGROUND

The pig gut microbiome harbors thousands of species of archaea, bacteria, viruses and eukaryotes such as protists and fungi. However, since the majority of published studies have been focused on prokaryotes, little is known about the diversity, host-genetic control, and contributions to host performance of the gut eukaryotic counterparts. Here we report the first study that aims at characterizing the diversity and composition of gut commensal eukaryotes in pigs, exploring their putative control by host genetics, and analyzing their association with piglets body weight.

RESULTS

Fungi and protists from the faeces of 514 healthy Duroc pigs of two sexes and two different ages were characterized by 18S and ITS ribosomal RNA gene sequencing. The pig gut mycobiota was dominated by yeasts, with a high prevalence and abundance of Kazachstania spp. Regarding protists, representatives of four genera (Blastocystis, Neobalantidium, Tetratrichomonas and Trichomitus) were predominant in more than the 80% of the pigs. Heritabilities for the diversity and abundance of gut eukaryotic communities were estimated with the subset of 60d aged piglets (N = 390). The heritabilities of α-diversity and of the abundance of fungal and protists genera were low, ranging from 0.15 to 0.28. A genome wide association study reported genetic variants related to the fungal α-diversity and to the abundance of Blastocystis spp. Annotated candidate genes were mainly associated with immunity, gut homeostasis and metabolic processes. Additionally, we explored the association of gut commensal eukaryotes with piglet body weight. Our results pointed to a positive contribution of fungi from the Kazachstania genus, while protists displayed both positive (Blastocystis and Entamoeba) and negative (Trichomitus) associations with piglet body weight.

CONCLUSIONS

Our results point towards a minor and taxa specific genetic control over the diversity and composition of the pig gut eukaryotic communities. Moreover, we provide evidences of the associations between piglets' body weight after weaning and members from the gut fungal and protist eukaryote community. Overall, this study highlights the relevance of considering, along with that of bacteria, the contribution of the gut eukaryote communities to better understand host-microbiome association and their role on pig performance, welfare and health.

Temporal variation of eukaryotic community structures in UASB reactor treating domestic sewage as revealed by 18S rRNA gene sequencing

Eukaryotes are important components of ecosystems in wastewater treatment processes. However, little is known about eukaryotic community in anaerobic wastewater treatment systems. In this study, eukaryotic communities in an up flow anaerobic sludge blanket (UASB) reactor treating domestic sewage during two years of operation were investigated using V4 and V9 regions of 18S rRNA gene for amplicon sequencing. In addition, activated sludge and influent sewage samples were also analyzed and used as the references for aerobic eukaryotic community to characterize anaerobic eukaryotes. The amplicon sequence V4 and V9 libraries detected different taxonomic groups, especially from the UASB samples, suggesting that commonly used V4 and V9 primer pairs could produce a bias for eukaryotic communities analysis. Eukaryotic community structures in the UASB reactor were influenced by the immigration of eukaryotes via influent sewage but were clearly different from the influent sewage and activated sludge. Multivariate statistics indicated that protist genera Cyclidium, Platyophrya and Subulatomonas correlated with chemical oxygen demand and suspended solid concentration, and could be used as bioindicators of treatment performance. Uncultured eukaryotes groups were dominant in the UASB reactor, and their physiological roles need to be examined to understand their contributions to anaerobic processes in future studies.

Coinfection with Entamoeba polecki and Brachyspira hyodysenteriae in a pig with severe diarrhea

Enteric disease in pigs is usually of multifactorial etiology, including infectious and non-infectious factors. In many cases of endemic diarrhea in weaner-to-finisher pigs, the combination of 2 or more microorganisms leads to aggravation of intestinal lesions and, consequently, clinical signs. We autopsied a 4-mo-old fattening pig with diarrhea and diagnosed severe fibrinonecrotizing typhlocolitis. Numerous spiral-shaped bacteria and amoeba-like PAS-positive protozoa were observed in the cecal and colonic mucosa and submucosa. Brachyspira hyodysenteriae was detected by PCR from colonic content. By in situ hybridization, large numbers of Entamoeba polecki were found within the lamina propria and submucosa; moderate numbers of Blastocystis sp. and scattered trichomonads were present in intestinal content. In addition, Entamoeba polecki, Balantidium spp., Blastocystis sp., and Trichomonas sp. were also detected by PCR.

Survey and Molecular Characterization of Trichomonads in Pigs in Anhui Province, East China, 2014

BACKGROUND

In pigs, several different trichomonad species such as Tritrichomonas foetus, Tetratrichomonas buttreyi, and Pentatrichomonas hominis have been described as inhabiting the digestive tract. However, little information is available on the epidemiology of these neglected parasites in the Chinese pig population.

METHODS

The prevalence of T. suis, T. buttreyi and P. hominis among 500 fecal specimens from pigs at seven pigs farms in Anhui Province in China between Oct and Dec 2014, was determined by PCR and DNA sequence analysis of the small subunit ribosomal RNA (SSU rRNA) genes.

RESULTS

The prevalence rates for T. suis, T. buttreyi, and P. hominis were 2.8% (14/500), 42.0% (210/500) and 7.8% (39/500), respectively. Mixed infections of two or three trichomonads were detected in 24 samples. The prevalence of the three trichomonads differed significantly between some age groups, with higher infection rates of T. suis and T. buttreyi in nursery pigs and P. hominis in preweaned pigs. The SSU rRNA sequences from T. suis and P. hominis showed 100% homology with their respective homologous database sequences. However, we observed minor allelic variations in the SSU rRNA sequences from T. buttreyi, and the five representative sequences identified were named firstly as types 1, 2, 3, 4 and 5. Moreover, type 1 was found to be dominant in the present study.

CONCLUSION

These findings highlight the potential risk posed by pigs in the transmission of trichomonad infections to humans and other animals.

Molecular and morphological diversity of the genus Hypotrichomonas (Parabasalia: Hypotrichomonadida), with descriptions of six new species

The genus HypotrichomonasLee, 1960 belongs to the small parabasalian class Hypotrichomonadea. Although five Hypotrichomonas species have been described from intestines of lizards and birds, some descriptions were brief and incomplete. Only the type species H. acosta has been observed repeatedly. We have established 23 strains of the genus Hypotrichomonas in culture. Phylogenetic and morphological analyses showed that these isolates represent eight distinct species, six of which are novel. Three of the species showed unusual morphology, such as a reduced undulating membrane, absence of the free part of the recurrent flagellum or a costa-like fiber. Our strains were isolated from a wide range of hosts including cockroaches, frogs, tortoises, lizards, snakes, marsupials, pigs, rodents, and primates. The genus Hypotrichomonas thus contains a relatively large number of species that differ in morphology, phylogenetic position and host range. It is remarkable that such diversity of hypotrichomonads was previously undetected, although a number of studies dealt with intestinal trichomonads of vertebrates and invertebrates. Our results indicate that the diversity of the genus Hypotrichomonas as well as of the whole Parabasalia is still only poorly understood, and the lineages described so far likely represent only a small fraction of the true diversity of parabasalids.

Molecular and morphologic identification of Pentatrichomonas hominis in swine

A marasmic pig with watery diarrhea was identified to harbor the human-pathogenic protist Pentatrichomonas hominis by PCR and sequence analysis of three genetic loci (ITS1-5.8S rRNA-ITS2, 18S rRNA, and EF-1α), electron microscopy, and infection experiments. DNA sequencing and phylogenetic analysis indicated the organism isolated in this study was most closely related to P. hominis. SEM and TEM observation of the ultrastructure demonstrated that it had a morphology identical to P. hominis. The result of experimental infections with P. hominis exhibited that the cells had the ability to propagate in the cecum of piglets and fecal-oral route might be the major way in which pigs became infected. The present study confirmed that swine could be a host for P. hominis and might serve as a reservoir for human trichomoniasis.

New Hosts of Simplicimonas similis and Trichomitus batrachorum Identified by 18S Ribosomal RNA Gene Sequences

Trichomonads are obligate anaerobes generally found in the digestive and genitourinary tract of domestic animals. In this study, four trichomonad isolates were obtained from carabao, dog, and pig hosts using rectal swab. Genomic DNA was extracted using Chelex method and the 18S rRNA gene was successfully amplified through novel sets of primers and undergone DNA sequencing. Aligned isolate sequences together with retrieved 18S rRNA gene sequences of known trichomonads were utilized to generate phylogenetic trees using maximum likelihood and neighbor-joining analyses. Two isolates from carabao were identified as Simplicimonas similis while each isolate from dog and pig was identified as Pentatrichomonas hominis and Trichomitus batrachorum, respectively. This is the first report of S. similis in carabao and the identification of T. batrachorum in pig using 18S rRNA gene sequence analysis. The generated phylogenetic tree yielded three distinct groups mostly with relatively moderate to high bootstrap support and in agreement with the most recent classification. Pathogenic potential of the trichomonads in these hosts still needs further investigation.

Molecular survey of Tritrichomonas suis (=T. foetus) 'cat' and 'cattle' genotypes in pigs in Japan

Tritrichomonas suis (=T. foetus) is a protozoan parasite of pigs, cattle and cats. Based on host range and genetic differences, T. suis has been divided into a 'cat genotype' and a 'cattle genotype', with the latter genotype capable of infecting both cattle and pigs. Since no information is currently available on the genetic characteristics of T. suis from pigs in Japan, we conducted a molecular survey of T. suis using fecal DNA from pigs in Japan. Of the 64 pigs examined, nested PCR revealed that 36 (56.3%) were positive for T. suis. Sequence analysis of 8 positive samples showed that 7 of the pig isolates belonged to the 'cattle genotype' and the remaining isolate belonged to the 'cat genotype'. The findings revealed that T. suis infection is common in pigs in Japan and that pigs can be infected by both genotypes.