Molecular characterization of Histomonas meleagridis and other parabasalids in the United States using the 5.8S, ITS-1, and ITS-2 rRNA regions

Genetic diversity of Trichomonads from Milu deer (Elaphurus davidianus) in China

The Milu deer, or Père David's deer (Elaphurus davidianus), a rare endemic species in China, represents a case of successful reintroduction of a species previously considered extinct in the wild. Trichomonads, protozoan symbionts capable of infecting vertebrates, are transmitted via the fecal-oral route; they are a subgroup of Parabasalia and include some pathogenic species that pose zoonotic risks. Until now, data on the diversity and prevalence of trichomonads in Chinese Milu deer have not been reported. To better understand the colonization status of trichomonads, fecal samples from 112 Milu deer across five nature reserves in China were collected. The ITS-1/5.8S/ITS-2 sequences were amplified using PCR to investigate the colonization rate of trichomonads and to assess evolutionary relationships and genetic characteristics through phylogenetic analysis. An occurrence of 38.39% was recorded in Milu deer, with sample collection sites (OR = 55.159, 95% CI = 3.166-961.113, p = 0.006), high relative humidity and average annual rainfall (OR = 11.675, 95% CI = 1.747-77.781, p = 0.011) identified as significant risk factors for trichomonads colonization. Undescribed trichomonads from four genera were identified, including Simplicimonas spp., Hypotrichomonas spp., Hexamastix spp., and Tetratrichomonas spp. To our knowledge, this is the first study to report on trichomonads in Milu deer in China. This study aims to enhance understanding of trichomonad colonization and associated risk factors, providing scientific guidance for the ex-situ conservation of Milu deer.

Diagnostic dilemma: application of real-time PCR assays for the detection of Dientamoeba fragilis in medical and veterinary specimens

BACKGROUND

Real-time PCR (qPCR) diagnostics developed for use in human clinical settings have been implemented to identify new animal hosts of the gastrointestinal protozoan Dientamoeba fragilis. The gut microbiome varies between species; unrecognised cross-reactivity could occur when applying these assays to new animal hosts. The use of qPCR diagnostics was assessed for the identification of new animal hosts of the gastrointestinal protozoan Dientamoeba fragilis.

METHODS

Forty-nine cattle, 84 dogs, 39 cats and 254 humans were screened for D. fragilis using two qPCR assays: EasyScreen (Genetic Signatures) and a laboratory-based assay commonly used in Europe. The reliability of the identifications made by these assays were assessed using melt curve analysis of qPCR products, conventional PCR targeting the SSU rDNA sequencing and NGS amplicon sequencing of qPCR product.

RESULTS

PCR products from the D. fragilis identified in cattle had a 9 °C cooler melt curve than when detected in humans. This melt curve discrepancy, indicative of cross-reactivity with an unknown organism, was investigated further. DNA sequencing determined that Simplicimonas sp. was the genera responsible for this cross-reactivity in cattle specimens. Dientamoeba fragilis was not detected in either dogs or cats. There was a discrepancy in the number of positive samples detected using the two qPCR assays when applied to human samples. The EasyScreen assay detected 24 positive samples; the laboratory-based assay detected an additional 34 positive samples. Of the discrepant samples, 5 returned sequence data for D. fragilis, and 29 were unsupported (false) positive samples.

CONCLUSIONS

Analysis of the melt curve after the qPCR reaction is a valuable technique to help differentiate samples containing D. fragilis compared to cross-reactions with non-target organisms. The identification of new animal hosts requires further evidence from either microscopy or DNA sequencing to confirm the presence of D. fragilis. Additionally, to reduce the risk of false-positive results due to non-specific amplification, we recommend reducing the number of PCR cycles to less than 40. Based on these results, we consider the ramifications of this identified cross-reactivity to the known host species distribution of D. fragilis.

Trichomonad Disease in Wild Turkeys (Meleagris gallopavo): Pathology and Molecular Characterization of Histomonas, Tetratrichomonas, Tritrichomonas, and Simplicimonas spp

The Wild Turkey (Meleagris gallopavo) is a geographically widespread, popular game bird and conservation icon in North America. Following successful reestablishment in parts of the US and Canada, regional declines have fueled population health concerns; therefore, understanding mortality causes and spatiotemporal patterns of disease is important to uncover potential ongoing and future health risks. Histomonosis, caused by the trichomonad Histomonas meleagridis, is a well-established and potentially fatal disease in Wild Turkeys; however, its prevalence and potential population health impacts remain poorly understood. Moreover, molecular tools recently have allowed for the detection of additional trichomonads that similarly can cause fatal disease in Wild Turkeys. We describe and compare disease due to H. meleagridis with that of Tetratrichomonas gallinarum, Tritrichomonas sp., and Simplicimonas sp. in Wild Turkeys in the southeastern US. Among 857 Wild Turkeys evaluated postmortem from 2002 to 2023, 34 (4.0%) were diagnosed with trichomonad disease, often assumed to be histomonosis prior to molecular testing. However, among 25 debilitating to fatal trichomonad disease cases for which etiologies were confirmed by PCR from 2015 to 2023, H. meleagridis was detected in 16/25 (64.0%), T. gallinarum in 6/25 (24.0%), Tritrichomonas sp. in 2/25 (8.0%) and Simplicimonas sp. in 1/25 (4.0%). These turkeys had similar clinical manifestations, and although lesion patterns varied to some extent, liver and/or intestinal tract was most commonly affected. Coinfections were common among all turkeys with trichomonad disease from 2015 to 2023 (21/25, 84.0%) and included viruses (lymphoproliferative disease virus, avian poxvirus), bacteria (Streptococcus gallolyticus, Listeria monocytogenes, Escherichia coli), and other protozoa (Sarcocystis sp., Haemoproteus sp.). Our results highlight the importance of molecular diagnostic testing in determining etiologies of trichomonad disease in Wild Turkeys. Further evaluation of the epidemiology and pathogenesis of trichomonad disease and its varied etiologies in Wild Turkeys and other birds is warranted to better understand risk factors and potential health impacts.

Health Assessment of Adult Male Eastern Wild Turkeys (Meleagris gallopavo silvestris) from Western Kentucky, USA

Wild turkeys (Meleagris gallopavo) are an important game species throughout the geographic range. Populations throughout multiple regions of the US have been declining, including in Kentucky, US, raising concerns among managers and resource users. To better understand the overall population health, we performed postmortem examinations and targeted pathogen, mineral, and toxicant testing on 36 adult male, apparently healthy, wild turkeys that were hunter harvested in western Kentucky during April 2018. We found that birds were in fair to good nutritional condition with no significant gross or microscopic lesions. Ticks (Amblyomma spp.) and lice (three species) were present on 94 and 31% of birds, respectively. We commonly detected intestinal nematodes and cestodes and found coccidian oocysts in 39% and capillarid eggs in 6% of birds. The prevalences of lymphoproliferative disease virus and reticuloendotheliosis virus were 39 and 11%, respectively. Spleen samples tested with PCR were positive for Borrelia burgdorferi, Haemoproteus sp., and Leucocytozoon sp. in 11, 83, and 3%, respectively. Based on a subjective histologic assessment of testis tissues, most birds had widespread and abundant sperm present. Mineral analysis and broad toxicant screening on liver samples from 32 turkeys were unremarkable. Further work is needed to assess potential population risk factors and to determine individual- and population-level impacts of pathogens on adults and poults.

Antimicrobial Peptides (AMP) in the Cell-Free Culture Media of Xenorhabdus budapestensis and X. szentirmaii Exert Anti-Protist Activity against Eukaryotic Vertebrate Pathogens including Histomonas meleagridis and Leishmania donovani Species

Anti-microbial peptides provide a powerful toolkit for combating multidrug resistance. Combating eukaryotic pathogens is complicated because the intracellular drug targets in the eukaryotic pathogen are frequently homologs of cellular structures of vital importance in the host organism. The entomopathogenic bacteria (EPB), symbionts of entomopathogenic-nematode species, release a series of non-ribosomal templated anti-microbial peptides. Some may be potential drug candidates. The ability of an entomopathogenic-nematode/entomopathogenic bacterium symbiotic complex to survive in a given polyxenic milieu is a coevolutionary product. This explains that those gene complexes that are responsible for the biosynthesis of different non-ribosomal templated anti-microbial protective peptides (including those that are potently capable of inactivating the protist mammalian pathogen Leishmania donovanii and the gallinaceous bird pathogen Histomonas meleagridis) are co-regulated. Our approach is based on comparative anti-microbial bioassays of the culture media of the wild-type and regulatory mutant strains. We concluded that Xenorhabdus budapestensis and X. szentirmaii are excellent sources of non-ribosomal templated anti-microbial peptides that are efficient antagonists of the mentioned pathogens. Data on selective cytotoxicity of different cell-free culture media encourage us to forecast that the recently discovered "easy-PACId" research strategy is suitable for constructing entomopathogenic-bacterium (EPB) strains producing and releasing single, harmless, non-ribosomal templated anti-microbial peptides with considerable drug, (probiotic)-candidate potential.

Experimental reproduction of histomonosis caused by Histomonas meleagridis genotype 2 in turkeys can be prevented by oral vaccination of day-old birds with a monoxenic genotype 1 vaccine candidate

Histomonosis (syn. blackhead disease) is caused by the protozoan parasite Histomonas meleagridis and can result in high mortality in turkey flocks, a situation driven by the limitation of prophylactic and therapeutic interventions. Multi-locus sequence typing confirmed the existence of two genotypes, with the vast majority of reported histomonosis outbreaks being caused by genotype 1 in contrast to only a few detections of genotype 2. For the first time, genotype 2 of H. meleagridis was successfully isolated from an outbreak of histomonosis in a flock of 5-week-old turkeys and a clonal culture was established. Using this culture, an experimental infection was performed in naïve turkeys. The animal trial reflected the observations from the field outbreak and coincided with a previously reported case of histomonosis caused by genotype 2, albeit no mortality was observed in the infected birds whereas 17.1% mortality was noticed in the field outbreak from appearance of disease until slaughter. Post mortem investigations demonstrated that lesions were restricted to the caeca in the field outbreak and the experimental trial. In parallel with the experimental reproduction of pathological changes, an oral vaccination of day-old turkeys with a monoxenic genotype 1 vaccine was carried out to determine efficacy against a genotype 2 challenge. Successful vaccine uptake was characterized by the presence of the vaccine in the caeca determined by qPCR and immunohistochemistry (IHC). Excretion of the vaccine strain was confirmed prior challenge, with the majority of birds developing antibodies. The new monoxenic vaccine was able to minimize lesions in the caeca demonstrating heterologous protection. No parasites were detected in the liver by IHC in any of the vaccinated birds, compared to non-vaccinated animals. However, in 6 out of 17 birds of the vaccinated group a positive signal was obtained by real time PCR from liver samples with 2 positives being typeable by conventional PCR as genotype 2. Overall, H. meleagridis genotype 2 infection was successfully reproduced. Experimental vaccination with a genetically distantly related genotype 1 was able to reduce lesions, supporting protection by a recently developed vaccine candidate as an efficacious prophylactic strategy.

Histomonosis in Poultry: A Comprehensive Review

Histomonas meleagridis, the etiological agent of histomonosis, is a poultry parasite primarily detrimental to turkeys. Characteristic lesions occur in the liver and ceca, with mortalities in turkey flocks often reaching 80-100%. Chickens and other gallinaceous birds can be susceptible but the disease was primarily considered sub-clinical until recent years. Treating and preventing H. meleagridis infection have become more difficult since 2015, when nitarsone was voluntarily removed from the market, leaving the poultry industry with no approved prophylactics, therapeutics, or vaccines to combat histomonosis. Phytogenic compounds evaluated for chemoprophylaxis of histomonosis have varied results with in vitro and in vivo experiments. Some recent research successes are encouraging for the pursuit of antihistomonal compounds derived from plants. Turkeys and chickens exhibit a level of resistance to re-infection when recovered from H. meleagridis infection, but no commercial vaccines are yet available, despite experimental successes. Safety and stability of live-attenuated isolates have been demonstrated; furthermore, highly efficacious protection has been conferred in experimental settings with administration of these isolates without harming performance. Taken together, these research advancements are encouraging for vaccine development, but further investigation is necessary to evaluate proper administration age, dose, and route. A summary of the published research is provided in this review.

Retrospective investigation of Echinococcus canadensis emergence in translocated elk (Cervus canadensis) in Tennessee, USA, and examination of canid definitive hosts

BACKGROUND

Few reports of Echinococcus spp. have been described in the USA; however, the geographical distribution of Echinococcus spp. in wild hosts is increasing consequent to human activities. In the early 2000's, 253 elk (Cervus canadensis) originating from Alberta, Canada were released into the Great Smoky Mountains National Park and North Cumberland Wildlife Management Area in an effort to re-establish their historical range.

METHODS

We investigated the prevalence of Echinococcus spp. in re-established elk populations in the North Cumberland Wildlife Management Area and the Great Smoky Mountains National Park via a retrospective analysis of banked elk tissues and helminth examinations on intestinal contents from coyotes (Canis latrans) from the North Cumberland Wildlife Management Area.

RESULTS

Four elk were PCR and sequence positive for E. canadensis. Each sequence had 98% or greater coverage and identity to multiple E. canadensis genotypes on GenBank. Adult Echinococcus spp. were not detected in any of the coyotes examined in this study.

CONCLUSIONS

Continued surveillance of this disease in susceptible species in these areas is warranted, and these data further underscore the risk of zoonotic pathogen introduction secondary to wildlife translocation.

Tetratrichomonas gallinarum granuloma disease in a flock of free range layers

Granuloma disease in a flock of free range productive layers in the Netherlands in 2017 is described. The disease resembled granuloma outbreaks in layers caused by Tetratrichomonas gallinarum in 2013 and occurred in the same area in which the rearing farm considered as the source of the 2013 outbreaks was located. Between 55 and 84 weeks of age mortality was 20.3% (breeder's norm 3.9%). All dead hens examined (n = 20) showed granulomas especially in liver and ceca. Nine hens with or without liver and/or ceca granulomas were examined for trichomonads in mentioned organs by in situ hybridization (ISH), nested PCR, and cloning and sequencing. Ceca were also examined by culture. T. gallinarum ISH was positive in all livers and ceca with granulomas and negative in case granulomas were absent. T. gallinarum strain 13/16632, which caused the 2013 outbreaks was found in 4/8 hens with granulomas. Moreover, other trichomonads were detected: a T. gallinarum strain GPO-like and a Simplicimonas sp. strain GABC1-like. Mixed infections also occurred. Infectious causes of granuloma disease other than the afore-mentioned trichomonads could be excluded. Trichomonad DNA was not detected in environmental samples and wild ducks originating from the farm of concern, except for one duck in which the same Simplicimonas sp. as in hens was detected, leaving the source of the T. gallinarum infection in hens unknown. It is concluded that the herein described granuloma disease likely was caused by T. gallinarum strain 13/16632. However, the pathogenicity of the other trichomonads found remains to be clarified.

Epidemic Characteristics of Clinical Histomoniasis in Chicken Flocks in Eastern China

Preliminary diagnosis of clinical symptoms and gross lesions with subsequent histopathologic and PCR analyses revealed histomoniasis in 276 chicken flocks in Jiangsu Province, China, and surrounding areas from January 2012 to December 2015. Detailed statistical analysis was performed to explore the occurrence and epidemic characteristics of histomoniasis in chicken flocks. The results indicated that histomoniasis usually occurred in free-range flocks of local broilers and laying hens. Also, 2- to 3-mo-old chickens were most susceptible to infection, and adult chickens rarely developed infection. The morbidity rate of chickens was generally 10%-30%, with mortality rates of less than 10%. Moreover, histomoniasis is a seasonal disease, occurring most often from April to June, and the rate of coinfection with heterakids in the ceca of infected chicken was 50.8%. The symptoms of diseased chickens included mental fatigue, bowing of the head and wings, and yellowish green droppings, with bloody stool in very limited cases. Most of the pathologic changes were characteristic of the disease, but there were also some atypical lesions confirmed by laboratory techniques. In the current study, the histomoniasis epidemic was first investigated in Chinese chicken flocks, and the results provided a useful reference for further study of this disease.

Interactions Between Parasites and the Bacterial Microbiota of Chickens

Except for the important role coccidia have as predisposing factors of necrotic enteritis, the role parasites play in the dynamics of a healthy microbiota of chickens is not well explored. This review describes the interactions of relevant intestinal parasites of chickens with bacteria. Infection with Eimeria spp. favor the growth of Clostridium perfringens and suppress the growth of many other bacteria by increasing viscosity and passage time of the ingesta, and by causing lesions to the intestinal mucosa that improve the availability of nutrients for C. perfringens. Conversely, there are indications that bacteria influence the course of disease after infections with Eimeria spp. Not much is known about intestinal cryptosporidiosis in chickens, but results in mice show that the intestinal microbiota induces some resistance against infection with Cryptosporidium parvum and that the innate immune response triggered by infections with cryptosporidia might have an effect on other intestinal microbes. Histomonas meleagridis depend on bacteria in vitro, and in vivo it will cause lesions in chickens only in the presence of bacteria. Blastocystis spp. are very common in chickens, but there is no information about interactions with bacteria. In humans, there is evidence of the correlation of the detection of Blastocystis and changes in the intestinal microbiota. There are indications of interactions between Ascaridia galli and various bacteria in chickens and Ascaridia spp. of mammals are known to produce various types of antimicrobial molecules. However, often the underlying mechanisms of these interactions between parasites and bacteria remain unknown and only correlations but not causation can be established.

Human intestinal parasites in Mahajanga, Madagascar: The kingdom of the protozoa

INTRODUCTION

Intestinal parasitic infections are a major public health problem in inter-tropical areas. The aim of our study was to describe the situation in Mahajanga, Madagascar with a particular focus on two protozoa, Dientamoeba fragilis and Blastocystis sp.

METHODS

This was a prospective study from February to June 2015. Stool samples from symptomatic hospitalized patients and asymptomatic volunteers were submitted to microscopy and molecular assays in order to detect parasites.

RESULTS

A wide panel of intestinal parasites were identified among the 265 included subjects, protozoa being the most prevalent with 72.8% whereas the prevalence of helminths and microsporidia was of 7.9% and 4.5%, respectively. Blastocystis sp. was the most prevalent protozoa (64.5% of the entire cohort) followed by various amoebas (35.5%) and flagellates (27,5%). We only detected subtypes 1, 2 and 3 of Blastocystis sp. Among the patients positive for D. fragilis (9.4%), 23 carried genotype 1 and 1 genotype 2. For the first time, we detected in 4 human stools the DNA of a recently described protozoon, Simplicimonas similis. Interestingly, subjects living in urban areas harbored significantly more different parasitic species than subjects living in rural areas with a correlation between sanitary level of neighborhood and protozoan infection. However, there was no difference in prevalence of digestive symptoms between parasite-free and parasite-infected subjects, except for Giardia intestinalis which had more symptomatic carriers.

DISCUSSION

Our study reveals a high overall parasite prevalence, similar to what had been found in 2003 in the same city and to other prevalence studies conducted in Africa. The poor access of the population to sanitary infrastructures may explain this result. Data from our study provide valuable key for sanitation programs and prevention of fecal-related infectious diseases.

Systemic Histomoniasis in a Leucistic Indian Peafowl (Pavo cristatus) from Southern Brazil

The pathological and molecular findings associated with Histomonas meleagridis are described in a leucistic Indian peafowl (Pavo cristatus) from Southern Brazil. The most significant gross findings were multifocal necrotizing hepatitis and diphtheric typhlitis. Histopathologic evaluation of the liver, ceca, kidney, spleen, and small intestine revealed systemic histomoniasis (SH) associated with intralesional and intravascular accumulations of histomonad organisms consistent with H. meleagridis. PCR was used to amplify the DNA of H. meleagridis from the liver, ceca, small intestine, spleen, lungs, and kidneys. Direct sequencing and phylogenetic analyses confirmed that the isolate of the flagellated trichomonad identified from this investigation is more phylogenetically related to H. meleagridis than Tetratrichomonas gallinarum, Tritrichomonas foetus, and Dientamoeba fragilis. These results confirmed the occurrence of SH in this peafowl and add to the diagnosis of this disease in birds from Brazil. This report might represent the first complete identification of spontaneous histomoniasis in a peafowl due to pathological and molecular characteristics and one of the few documented cases of SH in non-commercial birds.

Molecular characterization of internal transcribed spacer 1 (ITS 1) region of different Trypanosoma evansi isolates of India

Six Trypanosoma evansi isolates collected from ponies (PH1 and PK6), camel (CB2), donkeys (DJ3 and DH4) and cattle (CK5) from Haryana, Rajasthan, Uttar Pradesh and Gujarat states of India were used for molecular characterization of internal transcribed spacer 1 (ITS 1). The DNA was isolated from purified trypanosomes of these six isolates after propagation in mice model. ITS1-PCR of purified parasite DNA yielded an amplification product approximately 540 bp in size. Nucleotide sequence of ITS1 gene of CB2 isolate had 530 bp while CK5, DH4, DJ3, and PH1 isolates had 532 bp, whereas, PK6 isolates had 533 bp size. Blast data of the Indian isolates revealed 99 % homology with other available sequences of T. evansi. Multiple alignment of nucleotide sequence of ITS1 gene variants from Indian T. evansi isolates with selected homologous sequences from GenBank revealed that nucleotide substitution mostly occurred at the position of 101-103, 218-223, 243-244, 301-396 and 470-480. The isolates PH1, CK5, DH4 and DJ3 were found more associated with T. evansi isolates from the Philippines, Thailand, Iran, Egypt and China, whereas, PK6 and CB2 isolates were related to each other and were phylogenetically distant from rest of the Indian isolates used in this study. Based on the ITS1 rDNA sequence, the Neighbour-Joining consensus tree indicated clear evidence of existence of genetic diversity among T. evansi isolates from India.

Daphnia parasite dynamics across multiple Caullerya epidemics indicate selection against common parasite genotypes

Studies of parasite population dynamics in natural systems are crucial for our understanding of host-parasite coevolutionary processes. Some field studies have reported that host genotype frequencies in natural populations change over time according to parasite-driven negative frequency-dependent selection. However, the temporal patterns of parasite genotypes have rarely been investigated. Moreover, parasite-driven negative frequency-dependent selection is contingent on the existence of genetic specificity between hosts and parasites. In the present study, the population dynamics and host-genotype specificity of the ichthyosporean Caullerya mesnili, a common endoparasite of Daphnia water fleas, were analysed based on the observed sequence variation in the first internal transcribed spacer (ITS1) of the ribosomal DNA. The Daphnia population of lake Greifensee (Switzerland) was sampled and subjected to parasite screening and host genotyping during C. mesnili epidemics of four consecutive years. The ITS1 of wild-caught C. mesnili-infected Daphnia was sequenced using the 454 pyrosequencing platform. The relative frequencies of C. mesnili ITS1 sequences differed significantly among years: the most abundant C. mesnili ITS1 sequence decreased and rare sequences increased over the course of the study, a pattern consistent with negative frequency-dependent selection. However, only a weak signal of host-genotype specificity between C. mesnili and Daphnia genotypes was detected. Use of cutting edge genomic techniques will allow further investigation of the underlying micro-evolutionary relationships within the Daphnia-C. mesnili system.

Histomonas meleagridis--new insights into an old pathogen

The protozoan flagellate Histomonas meleagridis is the etiological agent of histomonosis, first described in 1893. It is a fastidious disease in turkeys, with pathological lesions in the caeca and liver, sometimes with high mortality. In chickens the disease is less fatal and lesions are often confined to the caeca. The disease was well controlled by applying nitroimidazoles and nitrofurans for therapy or prophylaxis. Since their introduction into the market in the middle of the previous century, research nearly ceased as outbreaks of histomonosis occurred only very rarely. With the ban of these drugs in the last two decades in North America, the European Union and elsewhere, in combination with the changes in animal husbandry, the disease re-emerged. Consequently, research programs were set up in various places focusing on different features of the parasite and the disease. For the first time studies were performed to elucidate the molecular repertoire of the parasite. In addition, research has been started to investigate the parasite's interaction with its host. New diagnostic methods and tools were developed and tested with samples obtained from field outbreaks or experimental infections. Some of these studies aimed to clarify the introduction of the protozoan parasite into a flock and the transmission between birds. Finally, a strong focus was placed on research concentrated on the development of new treatment and prophylactic strategies, urgently needed to combat the disease. This review aims to summarize recent research activities and place them into context with older literature.

Molecular characterization of various trichomonad species isolated from humans and related mammals in Indonesia

Trichomonad species inhabit a variety of vertebrate hosts; however, their potential zoonotic transmission has not been clearly addressed, especially with regard to human infection. Twenty-one strains of trichomonads isolated from humans (5 isolates), pigs (6 isolates), rodents (6 isolates), a water buffalo (1 isolate), a cow (1 isolate), a goat (1 isolate), and a dog (1 isolate) were collected in Indonesia and molecularly characterized. The DNA sequences of the partial 18S small subunit ribosomal RNA (rRNA) gene or 5.8S rRNA gene locus with its flanking regions (internal transcribed spacer region, ITS1 and ITS2) were identified in various trichomonads; Simplicimonas sp., Hexamastix mitis, and Hypotrichomonas sp. from rodents, and Tetratrichomonas sp. and Trichomonas sp. from pigs. All of these species were not detected in humans, whereas Pentatrichomonas hominis was identified in humans, pigs, the dog, the water buffalo, the cow, and the goat. Even when using the high-resolution gene locus of the ITS regions, all P. hominis strains were genetically identical; thus zoonotic transmission between humans and these closely related mammals may be occurring in the area investigated. The detection of Simplicimonas sp. in rodents (Rattus exulans) and P. hominis in water buffalo in this study revealed newly recognized host adaptations and suggested the existence of remaining unrevealed ranges of hosts in the trichomonad species.

Retrospective study of central nervous system lesions and association with Parelaphostrongylus species by histology and specific nested polymerase chain reaction in domestic camelids and wild ungulates

Formalin-fixed, paraffin-embedded tissues from elk ( Cervus elaphus), goats, and camelids with case histories and lesions suggestive of Parelaphostrongylus tenuis were examined by histology to characterize lesions that could aid in definitively diagnosing P. tenuis infection. Additionally, sections of paraffin-embedded tissue were used in a nested polymerase chain reaction (nPCR) using Parelaphostrongylus-specific primers to determine how PCR results corresponded with histological findings. Histological changes in brain and spinal cord consisted of linear tracks of hemorrhage; tracks or perivascular accumulations of hemosiderin-laden macrophages; acute foci of axonal degeneration and/or linear glial scars; and perivascular, parenchymal, or meningeal accumulations of eosinophils and/or lymphocytes and plasma cells. Of the 43 samples with histologic lesions consistent with neural larval migrans, 19 were PCR positive; however, only 8 were confirmed Parelaphostrongylus by DNA sequencing. Additionally, 1 goat was identified with a protostrongylid that had a 97% identity to both Parelaphostrongylus odocoilei and a protostrongylid nematode from pampas deer ( Ozotoceros bezoarticus celer) from Argentina. None of the histologic lesions individually or in combination correlated statistically to positive molecular tests for the nematode. The results indicate that it is possible to extract Parelaphostrongylus DNA from formalin-fixed, paraffin-embedded tissue, but extended fixation presumably can cause DNA crosslinking. Nested PCR provides another diagnostic tool to identify the cause of neurologic disease in camelids and elk with histologic lesions consistent with neural larval migrans. Furthermore, potential novel protostrongylid DNA was detected from a goat with lesions consistent with P. tenuis infection, suggesting that other neurotropic Parelaphostrongylus species may occur locally.

Multi-locus typing of Histomonas meleagridis isolates demonstrates the existence of two different genotypes

Histomonas meleagridis is the aetiological agent of histomonosis or “blackhead disease”. Histomonosis is of special importance today, because there is no effective treatment to prevent its occurrence with considerable losses for the poultry industry. Despite its importance only a few molecular studies have yet been performed to investigate the degree of genetic diversity between different isolates of this parasite. In the present study a collection of well defined samples, previously shown positive for the DNA of H. meleagridis, was used to investigate genetic relatedness of the parasite. Samples originated from 25 turkey flocks collected in France between 2007 and 2010. Additionally, diagnostic samples, collected at our Clinic in Vienna, from different European countries and Azerbaijan, during 2010 to 2013 were included in the analyses. For the analysis three different genetic loci were analyzed: 18S rRNA, α-actinin1 and rpb1 genes. To amplify partial sequences of α-actinin1 and rpb1 genes, primers specifically targeting H. meleagridis were designed. Following PCR, the sequences of 18S rRNA, α-actinin1 and rpb1 loci were analyzed. Phylogenetic analyses demonstrated separation of H. meleagridis isolates in two different clusters. The majority of isolates grouped within the cluster 1 and originated from different European countries. The cluster 2 was rare and predominantly found in samples originating from France. Considering that the genetic variability of clusters can be seen as two distinct genetic types we propose the term genotype instead of cluster.

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.

An outbreak of blackhead disease (Histomonas meleagridis) in farm-reared bobwhite quail (Colinus virginianus)

An outbreak of blackhead disease (Histomonas meleagridis) in farm-reared flock of 13,500 bobwhite quail (Colinus virginianus) resulted in mortality totaling approximately 1500 in 4 wk. Necropsy of 56 dead birds at midoutbreak (from a total that day of 131) revealed that 55 had severe cecal lesions typical of blackhead, and only 3 had visible lesions in the liver. Necropsy of apparently healthy birds failed to detect any signs of infection. Presence of H. meleagridis in affected ceca was proved by culture in vitro and PCR tests.