Dual-pathogen etiology of avian trichomonosis in a declining band-tailed pigeon population

Molecular detection and characterization of Trichomonas gallinae isolated from ornamental birds in Tehran, Iran

Trichomonas gallinae is a widespread protozoan parasite that primarily affects birds, causing a disease known as avian trichomonosis. The present study aimed to investigate the prevalence and genetic diversity of T. gallinae, a parasite causing avian trichomoniasis in feral pigeons, budgerigars, and finches in Tehran, Iran. The 5.8S ribosomal RNA locus, along with the internal transcribed spacer 2 (ITS2) region, has been extensively utilized for genotype identification and for determining inter- and intra-specific diversity. More recently, the Fe-hydrogenase (Fe-Hyd) gene has been suggested as an additional genetic marker to enhance the accuracy of strain subtyping discrimination. In the present study, a total of 12% (12/100) birds examined were infected with T. gallinae using microscopy and PCR methods. Infection was found in seven of 30 (23.3%) feral pigeons, three of 40 (7.5%) budgerigars, and two of 30 (6.66%) finches. Analysis of the ITS2 region of T. gallinae isolates revealed two highly similar sequences. The first sequence (GenBank: OQ689964-OQ689970) was found in five feral pigeons and two budgerigars, whereas the second sequence (GenBank: OQ689971-OQ689975) was identified in two feral pigeons, one budgerigar, and two finches. Phylogenetic analysis confirmed the presence of two distinct clusters (cluster I and cluster II) within the trichomonads based on the ITS2 region. However, further analysis using Fe-Hyd revealed greater diversity, with three subtypes identified (A1, A2, and C1). One isolate identified in the present study (GenBank accession number: OQ694508.1) belonged to subtype A1. Combining ITS2 and Fe-Hyd markers holds promise for a more comprehensive understanding of the population structure of T. gallinae and the potential role of ITS2 in host adaptation.

Prevalence and molecular characterization of Trichomonas gallinae from pigeons in Anhui, China

Trichomonas gallinae, a protozoan parasite causing avian trichomonosis, exhibits a widespread global prevalence. It primarily affects the upper digestive tract of birds and has resulted in significant ecological problems worldwide. This study aimed to investigate the prevalence and genotypes of T. gallinae in Anhui Province, China. A total of 1612 oropharyngeal swab samples were collected from pigeon farms in Anhui Province to determine the prevalence of T. gallinae infection. The results revealed 565 (35.1%) positive samples of T. gallinae. Significant differences in infection rates were observed among different regions and age groups. Furthermore, the ITS1/5.8 S/ITS2 region was amplified, sequenced, and subjected to phylogenetic analysis. Genotypes A and B of T. gallinae were identified, and genotype B was the dominant genotype in Anhui Province. This is the first report on the prevalence and molecular characterization of T. gallinae in Anhui Province, China. Additionally, we integrated reports on the prevalence and genotype of T. gallinae in relevant provinces in China.

Genotypic diversity and epidemiology of Trichomonas gallinae in Columbidae: Insights from a comprehensive analysis

Trichomonas gallinae is a protozoa that parasitizes the upper gastrointestinal and respiratory tracts of various animals and birds, including Columbidae, Passeriformes, and Falconiformes. Polymerase chain reaction-based T. gallinae ITS1/5.8S/ITS2 gene typing yields inconsistent results owing to methodological differences. To standardize the statistical analysis of T. gallinae genotype distributions, this study employed MEGA-X software with the Tamamura 3-parameter (T92) + G model in the neighbor-joining method, with 2,000 bootstrap replicates, to calculate a systematic evolutionary tree. The resulting tree comprised 12 branches, ITS-OBT-Tg-1 to ITS-OBT-Tgl, with similar phylogenetic relationships. Relevant literature review yielded T. gallinae prevalence data in Columbidae. Statistical analysis was conducted from two perspectives: non-biological and biological factors, using chi-square tests and ordered logistic regression analysis. T. gallinae positivity rates differed significantly across diverse regions (χ2 = 4,609.9, P = 0.000, df = 4) and at various times (χ2 = 2,810.8, P = 0.000, df = 3). However, temperature and precipitation did not significantly affect T. gallinae positivity rates. Additionally, T. gallinae positivity rates differed significantly among diverse hosts (χ2 = 2,958.6, P = 0.000, df = 14) and by host age (χ2 = 478.5, P = 0.000, df = 2) and sex (χ2 = 96.00, P = 0.000, df = 1). This comprehensive analysis aimed to control T. gallinae transmission, reduce economic and species resource losses, and provide a foundation for future related research.

First reported case of Trichomonas gallinae infection in red-breasted toucan (Ramphastos dicolorus)

This study reports the infection and diagnosis of the protozoan morphologic complex Trichomonas gallinae in a baby red-breasted toucan (Ramphastos dicolorus). Nodular lesions on the soft palate and edema in the oral cavity were observed macroscopically. Microscopically, a granuloma with multiple layers of necrosis interspersed with inflammatory polymorphonuclear infiltrates was observed. Parasitism was confirmed by parasitological diagnosis, isolation of the flagellates in culture medium, and Polymerase Chain Reaction (PCR) using 5.8S ribosomal RNA (rRNA). Flanking internal transcribed spacer (ITS) gene regions were amplified by polymerase chain reaction, and the sequences were analyzed phylogenetically using MEGA 11 software. Phylogenetic analysis based on ITS1/5.8S rRNA/ITS2 sequences demonstrated high nucleotide identity with two Trichomonas sequences available in GenBank, which were more closely related to T. vaginalis (99%) than to T. gallinae (98%). In addition to being potential transmitters of this protozoan, rigorous monitoring of infectious and parasitic diseases in wild bird populations is essential for their preservation. The forms of transmission of Trichomonas sp. favor the occurrence of the disease in many non-Columbiformes species, which is essential for the monitoring of this disease in wild birds.

Identification of new drug candidates against Trichomonas gallinae using high-throughput screening

Trichomonas gallinae is a protozoan parasite that is the causative agent of trichomoniasis, and infects captive and wild bird species throughout the world. Although metronidazole has been the drug of choice against trichomoniasis for decades, most Trichomonas gallinae strains have developed resistance. Therefore, drugs with new modes of action or targets are urgently needed. Here, we report the development and application of a cell-based CCK-8 method for the high-throughput screening and identification of new inhibitors of Trichomonas gallinae as a beginning point for the development of new treatments for trichomoniasis. We performed the high-throughput screening of 173 anti-parasitic compounds, and found 16 compounds that were potentially effective against Trichomonas gallinae. By measuring the median inhibitory concentration (IC50) and median cytotoxic concentration (CC50), we identified 3 potentially safe and effective compounds against Trichomonas gallinae: anisomycin, fumagillin, and MG132. In conclusion, this research successfully established a high-throughput screening method for compounds and identified 3 new safe and effective compounds against Trichomonas gallinae, providing a new treatment scheme for trichomoniasis.

Adaptation of the classical end-point ITS-PCR for the diagnosis of avian trichomonosis to a real-time PCR reveals Bonelli's eagle as a new host for Trichomonas gypaetinii

Avian trichomonosis is a parasitic disease caused mainly by Trichomonas gallinae and other Trichomonas species. It can be asymptomatic, or it can produce a necrotic lesion in the upper digestive tract and spread to other organs, causing the death of the infected birds. In this study, we aimed to evaluate an adapted real-time PCR method for the diagnosis of different genotypes and species of avian oropharyngeal trichomonads. Fifty-six samples from the oropharynx of Bonelli's eagles (Aquila fasciata) obtained between 2018 and 2019 were analyzed using the real-time PCR and the end-point PCR, both targeting trichomonads ITS, and the results were compared by a coefficient of agreement. All positive samples were sequenced. The analysis showed a higher percentage of detection of real-time PCR ITS compared with end-point PCR ITS (64.3 vs 55.4%), and good agreement value (Kappa = 0.816). Melting temperature value for resulting amplicons of real-time PCR for avian trichomonads was 83.45 ± 0.72 °C. Genotypes A, D, and III were found among the sequences. Moreover, Trichomonas gypaetinii, a common species in scavenger birds, is reported for the first time in Bonelli's eagles.

Successful storage of Trichomonas gallinae on Whatman FTA cards following culture

Logistical constraints concerning parasite sample storage can hinder progress with the discovery of genetic variation on a global scale. New storage methods are being developed to address this, but require testing in order to understand how widely applicable these methods are. Whatman FTA cards have been tested previously under laboratory conditions for storing low-concentration Trichomonas gallinae isolates with the conclusion that they are not suitable, but have not been tested under field conditions. Here, we conducted a field-test, comparing FTA cards with storage in ethanol for T. gallinae samples collected and cultured from wild Columbiformes in Africa using standard field methods, before transportation to the UK. After 6 months storage, both methods resulted in an overall prevalence of 100% following PCR amplification (n = 59), suggesting that FTA cards are suitable for estimation of T. gallinae prevalence. However, samples stored in ethanol produced more, and longer, sequences than those stored on FTA cards. These data suggest storage in ethanol is preferable for the acquisition of high quality genetic strain data, but that FTA cards can be used successfully to ascertain infection prevalence and identify parasite strains under field conditions.

Assessing rates of parasite coinfection and spatiotemporal strain variation via metabarcoding: insights for the conservation of European Turtle Doves Streptopelia turtur

Understanding the frequency, spatiotemporal dynamics and impacts of parasite coinfections is fundamental to developing control measures and predicting disease impacts. The European turtle dove (Streptopelia turtur) is one of Europe's most threatened bird species. High prevalence of infection by the protozoan parasite Trichomonas gallinae has previously been identified, but the role of this and other coinfecting parasites in turtle dove declines remains unclear. Using a high‐throughput sequencing approach, we identified seven strains of T. gallinae, including two novel strains, from ITS1/5.8S/ITS2 ribosomal sequences in turtle doves on breeding and wintering grounds, with further intrastrain variation and four novel subtypes revealed by the iron‐hydrogenase gene. High spatiotemporal turnover was observed in T. gallinae strain composition, and infection was prevalent in all populations (89%–100%). Coinfection by multiple Trichomonas strains was rarer than expected (1% observed compared to 38.6% expected), suggesting either within‐host competition, or high mortality of coinfected individuals. In contrast, coinfection by multiple haemosporidians was common (43%), as was coinfection by haemosporidians and T. gallinae (90%), with positive associations between strains of T. gallinae and Leucocytozoon suggesting a mechanism such as parasite‐induced immune modulation. We found no evidence for negative associations between coinfections and host body condition. We suggest that longitudinal studies involving the recapture and investigation of infection status of individuals over their lifespan are crucial to understand the epidemiology of coinfections in natural populations.

To get sick or not to get sick-Trichomonas infections in two Accipiter species from Germany

Trichomonosis caused by the flagellate Trichomonas gallinae is one of the most important avian diseases worldwide. The parasite is localised in the oesophageal area of its host and mainly infects pigeon and dove species. During the last decade, a host expansion to passerine birds occurred, making the disease a potential threat for passerine predators as naïve host species. Here, we investigated the effect of the parasite on two Accipiter species in Germany which show a comparable lifestyle but differ in prey choice, the Northern goshawk (Accipiter gentilis) mainly hunting pigeons and the Eurasian sparrowhawk (Accipiter nisus) mainly feeding on passerines. We genetically identified the parasite strains using the Fe-Hydrogenase gene as marker locus and compared the incidence of parasite presence and clinical signs of trichomonosis between nestlings of the two Accipiter species. In total, we identified 14 strains, with nine strains unknown so far. There was a higher strain diversity and prevalence of Trichomonas spp. in goshawks than sparrowhawks (42.4% vs. 21.2%) whereas sparrowhawks when being infected more often displayed clinical signs of trichomonosis than goshawks (37.1% vs. 6.1%). Even though sparrowhawks were mainly infected with the finch epidemic strain and genetic data indicated some variation between isolates, no correlation with virulence could be detected. All in all, goshawks seem to be better adapted to Trichomonas infections, whereas to sparrowhawks, this is a novel disease with more severe manifestations, from individual morbidity to a higher risk of population decline caused by trichomonosis.

Genetic characterization of Trichomonas gallinae (Rivolta, 1878) in companion birds in Japan and the genotypical relationship in the Asia region

BACKGROUND/PURPOSE

Avian trichomonosis is a parasitic infection that affects a wide range of avian species, including free-ranging and pet birds worldwide, and Trichomonas gallinae has been considered as the only causative agent for decades. The sequence of the 5.8S ribosomal RNA with internal transcribed spacer (ITS) regions was widely used for identifying genotypes and determining inter-specific and intra-specific diversity. Moreover, the sequence of Fe-hydrogenase (FeHyd) was proposed as the second genetic marker for providing improved resolution of strain subtyping discrimination. Though the correlation between genetic variability and strain virulence is controversial, FeHyd analyses seemed to be useful to investigate the host or geographic origin of isolates. This study aimed to investigate the genetic characteristics of avian Trichomonas spp.

METHODS

Forty-seven oral swabs and crop lavage fluids were collected from 9 avian genera, which were diagnosed as Trichomonas-positive by microscopy in animal hospitals in Japan, were analyzed.

RESULTS

Genetic analysis of clonal isolates revealed the prevalence of the single genotype, ITS-OBT-Tg-1, by ITS region analysis, while two different subtypes, A2 and novel A3, were suggested by FeHyd gene analysis among Japanese companion birds. Phylogenetic analyses of available ITS sequences obtained from the Asia region (China, Iran, Iraq, and Saudi Arabia) were also preformed, revealing endemic ITS-OBT-Tg-1, ITS-OBT-Tg-2, ITS-OBT-Ttl-1, genotype III, and Saudi Arabia's unique lineages. Furthermore, ITS-OBT-Tg-2 predominance in these countries indicates different strains origination from Japan.

CONCLUSION

This is the first report of the genetic characterization of T. gallinae in Japan with discovery of novel subtype A3.

Parasites of domestic and wild pigeons in the south of Ukraine

Pigeons are closely related to human life and are both a source of food and object for hobbies and sports. Parasitic diseases of birds are the main reason for their growth retardation, reduced productivity and viability. The article presents the results of studying the prevalence of trichomonosis, cestodes and nematodes among the population of wild and domestic pigeons in the south of Ukraine. According to the results of the conducted researches it is established that in the south of Ukraine endoparasitoses of domestic and wild pigeons are quite widespread, and all species of this bird are carriers of Trichomonas gallinae. At the same time, the highest rate of Trichomonas infection was recorded in Columba palambus and C. livia domestica, and the overall infestation of males is higher by 4.4% compared to females. It was determined that domestic pigeons C. livia domestica were infested with trichomonosis (27.5%) and nematodes (Ascaridia columbae, 57.1%), C. palambus – trichomonosis (32.1%) and cestodes (Raillietina spp., 82.4%), Streptopelia turtur – cestodes (Raillietina spp., 12.5%) and S. decaocto – cestodes (Raillietina spp., 71.4%) and nematodes (Heterakis gallinarum, A. columbae – 33.3% and 44.4% respectively). The overall rate of infestation of pigeons with cestodes was 28.4% and the incidence in males was higher by 3.9% compared to females. It was found that the most common species among pigeon cestodes is Raillietina spp. In addition, 22.9% of pigeons are carriers of nematodes (H. gallinarum, A. columbae and Capillaria spp.). Continuous monitoring of pigeon parasites is necessary because they, in most cases, come into contact with other species of poultry and are a source of general invasion. In terms of further research, it would be promising to study the prevalence of helminthic infestation among wild migratory birds.

Molecular characterization of Trichomonas gypaetinii isolated from the upper alimentary tract of Steller's sea eagles (Haliaeetus pelagicus) and white-tailed sea eagles (Haliaeetus albicilla) in Hokkaido, Japan

Recent phylogenetic and morphologic studies of Trichomonas spp. suggests that there are more than 3 species that infect the upper alimentary tract of wild birds, which include T. gallinae, T. stableri, and T. gypaetinii. In this study, investigations were conducted on the prevalence of trichomonads in the upper alimentary tract of 12 Steller's sea eagles (Haliaeetus pelagicus) and 18 white-tailed sea eagles (H. albicilla). All birds were rescued from the wild and kept at a rehabilitation facility in Hokkaido, Japan, for variable durations and did not show any symptoms of trichomonosis. The ITS1-5.8SrRNA-ITS2 (ITS) genomic region of Trichomonas spp. was detected from 29 samples by PCR, and flagellates were confirmed from 4 samples by culture. Morphologic observations and measurement recordings were conducted under a light microscope on trophozoites obtained from the cultured isolates. Genomic sequences of the ITS, 18S ribosomal RNA (18S rRNA), Fe-hydrogenase, and RNA polymerase II largest subunit (Rpb1) regions were determined by direct sequencing, and phylogenetic analyses were conducted with previously published sequences of Trichomonas spp. All isolates were concluded as T. gypaetinii based on morphologic and molecular characterizations of the ITS and 18S rRNA genes. This is the first study to isolate T. gypaetinii from Haliaeetus eagles and further provide novel sequences of the Fe-hydrogenase and Rpb1 genes of T. gypaetinii. Both genomic regions also confirmed that T. gypaetinii belong to independent clusters from other Trichomonas spp.

Emergence and molecular characterization of pigeon Paramyxovirus-1 in non-native Eurasian collared doves (Streptopelia decaocto) in California, USA

Eurasian collared doves (Streptopelia decaocto) were introduced into Florida in the 1980s and have since established populations throughout the continental United States. Pigeon paramyxovirus-1 (PPMV-1), a species-adapted genotype VI Avian orthoavulavirus 1, has caused periodic outbreaks among collared doves in the U.S. since 2001 with outbreaks occasionally involving native doves. In California, PPMV-1 mortality events were first documented in Riverside County in 2014 with subsequent outbreaks in 23 additional counties from southern to northern California between 2015 and 2019. Affected collared doves exhibited torticollis and partial paralysis. Pale kidneys were frequently visible on gross necropsy (65.4%; 51/78) while lymphoplasmacytic interstitial nephritis often with acute tubular necrosis (96.0%; 24/25) and pancreatic necrosis (80.0%; 20/25) were common findings on histopathology. In total, PPMV-1 was confirmed by rRT-PCR and sequence analysis from oropharyngeal and/or cloacal swabs in 93.0% (40/43) of the collared doves tested from 16 California counties. In 2017, Avian orthoavulavirus 1 was confirmed in a native mourning dove (Zenaida macroura) found dead during a PPMV-1 outbreak in collared doves by rRT-PCR from formalin-fixed paraffin-embedded (FFPE) tissues, after the initial rRT-PCR from swabs failed to detect the virus. Molecular sequencing of the fusion protein of isolates collected from collared doves during outbreaks in 2014, 2016, and 2017 identified two distinct subgenotypes, VIa and VIn. Subgenotype VIn has been primarily isolated from collared doves in the southern U.S., while VIa has been isolated from mixed avian species in the northeastern U.S., indicating two independent introductions into California. While populations of collared doves are not expected to be substantially impacted by this disease, PPMV-1 may pose a threat to already declining populations of native columbids. This threat could be assessed by monitoring native and non-native columbids for PPMV-1. Based on our study, swab samples may not be sufficient to detect infection in native columbids and may require the use of non-traditional diagnostic approaches, such as FFPE tissues, to ensure virus detection.

Molecular detection and genetic characterization of Trichomonas gallinae in falcons in Saudi Arabia

Avian trichomonosis is primarily caused by Trichomonas gallinae, a flagellated protozoan parasite that especially infects the upper digestive tract of columbid bird species and their avian predators. However, this parasite has recently been found to be distributed worldwide in various other avian species. This parasitic disease is common in captive falcons in Saudi Arabia and the Middle East. This study aimed to examine and identify the genetic variation of T. gallinae obtained from three species of falcons in Saudi Arabia via the sequencing analysis of the internal transcribed spacer (ITS) region. Swab samples from 97 saker falcons (Falco cherrug), 24 peregrine falcons (Falco peregrinus) and 37 gyrfalcons (Falco rusticolus) were cultured and analysed for infection between 2018 and 2019. The overall prevalence of infection by T. gallinae was 26.58% (n = 42), of which 35 (83.33%) were collected from Riyadh region and seven (16.67%) were collected from Qassim region. The results indicate the presence of four genotypes of T. gallinae in Saudi falcons: A, C, II, and KSA11. This study reports for the first time genetic diversity of T. gallinae in these falcons in Saudi Arabia.

Oral trichomonosis: Description and severity of lesions in birds in Spain

Avian trichomonosis is a parasitic disease caused by the flagellated protozoan Trichomonas gallinae. Columbiformes are the reservoir host of the parasite, with high levels of infection, but also other domestic and wild birds from a variety of orders are susceptible to the infection and development of gross lesions. In this paper we describe the type and severity of lesions in wild birds in four avian orders (Accipitriformes, Falconiformes, Strigiformes and Columbiformes). A total of 94 clinical cases diagnosed of trichomonosis were selected for the categorization of their lesions in the upper digestive tract. The affected birds were classified into three different categories (mild, moderate and severe) based on size (in relation to the tracheal opening), depth and location of the lesions. Mild cases are those with small and superficial lesions far from the oropharyngeal opening; moderate cases possess larger and deeper lesions, and severe cases very large and deep lesions that impede swallowing or affect the skull. Mild lesions were found in 10.6 % of cases; moderate lesions were observed in 18.1 % of the birds and severe lesions in 71.3 %. Treatment outcomes in birds with either mild or moderate lesions were favorable, while severe lesions were related to poor body score, leading to death or euthanasia in most cases. A relationship between severe lesions and avian order was found, with a higher percentage of birds with this type in Falconiformes, Columbiformes and Strigiformes. Multifocal lesions were more frequent in Columbiformes and Falconiformes. In Strigiformes, 93.3 % of birds showed lesions in the upper jaw. This study seeks to further understanding of avian trichomonosis and to provide information that will be useful to veterinarians and related professionals for assessment, prognosis and treatment choice for these birds.

Clinical isolates of Tritrichomonas foetus in bulls in Wyoming, South Dakota and Montana, USA

BACKGROUND

Several Tritrichomonas species have been found in mammalian hosts. Among these trichomonads T. foetus is often found in the urogenital tract of cattle and the gastrointestinal tract of the domestic cat, resulting in sexually transmitted bovine trichomonosis and fecal-orally transmitted feline trichomonosis, respectively. The aims of the current study were to molecularly characterize clinical isolates of T. foetus in cattle populations in Wyoming, South Dakota, and Montana of the United States of America and to phylogenetically analyze Tritrichomonas species of mammalian hosts.

RESULTS

DNA sequencing of rRNA genes showed over 99% identity of the newly described isolates to other bovine isolates. Further, T. foetus isolates of various mammalian hosts originated in different geographic regions worldwide were clustered into two well-defined clades by phylogenetic analysis of rRNA and cysteine protease 2 genes. Clade I consisted of isolates originated from cattle, pig, and human whereas clade II contained isolates of cat and dog.

CONCLUSION

It is concluded that all mammalian Tritrichomonas spp. apparently belong to T. foetus. Analysis of more sequences is warranted to support this conclusion.

Trichomonosis in Greenfinches (Chloris chloris) in the Netherlands 2009-2017: A Concealed Threat

Finch trichomonosis in Europe is caused by a Trichomonas gallinae subtype A1 strain, considered to be clonal because lacking genetic heterogeneity in partial genotyping. The disease recently emerged and has been associated with a 66% reduction of the British breeding greenfinch (Chloris chloris) population. In contrast, in the Netherlands, where trichomonosis was detected in 2009, the breeding greenfinch population continued to grow in subsequent years. This study aimed to elucidate whether this discrepancy in population trends is because Trichomonas infection in Dutch greenfinches is associated with less severe disease, i.e., disease being less fatal. Therefore, it characterized and quantified trichomonosis in a convenience sample of greenfinches found dead and examined post-mortem between 2009 and 2017 and compared results to published data from Great Britain. Trichomonads were detected by cytology, histology, or culture in 95/101 greenfinches. The birds with trichomonads all had microscopic lesions in the upper digestive tract consistent with trichomonosis, indicating the trichomonads caused disease. The occurrence of significant lesions due to other causes was low. Some greenfinches with trichomonosis showed no macroscopic lesions. These birds showed significantly less ulceration of the mucosa and less extensive heterophil infiltration, but extent of macrophage infiltration and presence of bacteria was similar to that of birds with macroscopic lesions, and significant lesions due to other causes were equally rare. Therefore, trichomonosis was considered similarly fatal in both groups. The frequency of fatal trichomonosis in the Dutch greenfinches did not differ significantly from that reported from Great Britain. Partial genotyping of the ITS1-5,8S-ITS2 and Fe-hydrogenase regions of T. gallinae was performed to detect genetic heterogeneity, that could indicate the presence of other, possibly less virulent, strains. In 60/63 samples there was full alignment of sequences with the clonal strain of T. gallinae subtype A1. The remaining three samples had the same single synonymous nucleotide difference in the Fe-hydrogenase region; however, pathology is these three was identical to the others. Collectively, the results provide no clear evidence for less severe disease as explanation for the discrepancy in census data trends. We conclude that trichomonosis is a threat concealed in Dutch breeding greenfinch census data.

Membrane associated proteins of two Trichomonas gallinae clones vary with the virulence

Oropharyngeal avian trichomonosis is mainly caused by Trichomonas gallinae, a protozoan parasite that affects the upper digestive tract of birds. Lesions of the disease are characterized by severe inflammation which may result in fatality by starvation. Two genotypes of T. gallinae were found to be widely distributed in different bird species all over the world. Differences in the host distribution and association with lesions of both genotypes have been reported. However, so far no distinct virulence factors of this parasite have been described and studies might suffer from possible co-infections of different genotypes. Therefore, in this paper, we analyzed the virulence capacity of seven clones of the parasite, established by micromanipulation, representing the two most frequent genotypes. Clones of both genotypes caused the maximum score of virulence at day 3 post-inoculation in LMH cells, although significant higher cytopathogenic score was found in ITS-OBT-Tg-1 genotype clones at days 1 and 2, as compared to clones with ITS-OBT-Tg-2. By using one representative clone of each genotype, a comparative proteomic analysis of the membrane proteins enriched fraction has been carried out by a label free approach (Data available via ProteomeXchange: PXD013115). The analysis resulted in 302 proteins of varying abundance. In the clone with the highest initial virulence, proteins related to cell adhesion, such as an immuno-dominant variable surface antigen, a GP63-like protein, an armadillo/beta-catenin-like repeat protein were found more abundant. Additionally, Ras superfamily proteins and calmodulins were more abundant, which might be related to an increased activity in the cytoskeleton re-organization. On the contrary, in the clone with the lowest initial virulence, larger numbers of the identified proteins were related to the carbohydrate metabolism. The results of the present work deliver substantial differences between both clones that could be related to feeding processes and morphological changes, similarly to the closely related pathogen Trichomonas vaginalis.

An outbreak of trichomonosis in European greenfinches Chloris chloris and European goldfinches Carduelis carduelis wintering in Northern France

Avian trichomonosis is a common and widespread disease, traditionally affecting columbids and raptors, and recently emerging among finch populations mainly in Europe. Across Europe, finch trichomonosis is caused by a single clonal strain of Trichomonas gallinae and negatively impacts finch populations. Here, we report an outbreak of finch trichomonosis in the wintering populations of Chloris chloris (European greenfinch) and Carduelis carduelis (European goldfinch) from the Boulonnais, in northern France. The outbreak was detected and monitored by bird ringers during their wintering bird ringing protocols. A total of 105 records from 12 sites were collected during the first quarter of 2017, with 46 and 59 concerning dead and diseased birds, respectively. Fourteen carcasses from two locations were necropsied and screened for multiple pathogens; the only causative agent identified was T. gallinae. Genetic characterization was performed by four markers (small subunit ribosomal RNA, hydrogenosomal iron-hydrogenase, and RNA polymerase II subunit 1 genes, and the internal transcribed spacers (ITS) region) and confirmed the T. gallinae strain to be A1, which affects the finch populations of Europe. This was also confirmed by an ITS-based phylogenetic analysis which further illustrated the diversity of the Trichomonas infecting birds. Preliminary data on the survival and dispersion of infected birds were obtained from ring-returns of diseased individuals. The anthropogenic spread of diseases through bird feeding practices is highlighted and some suggestions to prevent pathogen transmission via backyard supplementary feeders for garden birds are given.

Avian trichomonosis mortality events in band-tailed pigeons (Patagioenas fasciata) in California during winter 2014-2015

Avian trichomonosis is an upper digestive tract disease of birds typically caused by the protozoan parasite Trichomonas gallinae. In California (U.S.A), trichomonosis is known to cause periodic epidemics in the Pacific Coast band-tailed pigeon (Patagioenas fasciata monolis), a migratory upland game bird. We summarize the mortality events that occurred during winter 2014-2015 including the duration, estimated mortality, pathology, and genetic identity of infecting parasites. Increased mortality was reported from locations in 25 counties between November 2014 and June 2015. Based on reports, carcasses received, wildlife rehabilitation center admissions, site visits, and regular monitoring by local personnel, total mortality was estimated at 18,440. At necropsy, birds had multiple coalescing lesions in the oral cavity involving the upper palate and/or around the tongue and glottis, esophagus, crop, and/or proventriculus. Birds collected from Contra Costa (63.9%; 30/47); Marin (75.0%; 6/8), San Mateo (46.7%; 14/30), and Santa Clara (35.0%; 37/106) counties were more likely to have lesions extending into their head involving muscle, sinuses, ear canals, eye sockets, and bone (χ2 = 62.9; df = 11; P < 0.001). Histopathologic findings included pharyngitis, esophagitis, myositis, and air sacculitis of the pneumatic bone of the skull. Mixed bacterial colonies were found multifocally at the fronts of the necrosis in six of the eleven birds examined histologically. Infecting trichomonads included T. gallinae subtype A2 (n = 5), un-typed T. gallinae (n = 4), mixed infection with T. gallinae subtype A2 and T. stableri (n = 1), and mixed infection with un-typed T. gallinae and T. stableri (n = 1). The winter 2014-2015 epidemic was the largest on record in terms of duration, locations, and birds affected. Infection dynamics may have been exacerbated by the drought in California. Increased monitoring of band-tailed pigeons is needed to understand the long-term impacts of large-scale mortality events on their population.

Prevalence of Trichomonas, Salmonella, and Listeria in Wild Birds from Southeast Texas

Infectious diseases can be a major threat to wildlife populations, especially in human-modified habitats, but infection rates in populations of wild animals are often poorly studied. Trichomonas, Salmonella, and Listeria are all pathogens known to infect birds, but their infection rates in wild bird populations are not well documented. This study documents infection rates of the three pathogens in wild bird populations inhabiting a suburban to rural gradient in Southeast Texas. Various species of wild birds were sampled at five sites in Southeastern Texas representing rural (<1 house per ha), exurban (approximately 1 house per ha), and suburban (approximately 10 houses per ha) habitat types. Birds were captured in mist nets and samples were taken from the oral cavity, crop, and vent to detect the presence of pathogens. Samples were screened for Trichomonas by examining wet mounts under a light microscope, whereas samples were screened for Salmonella and Listeria by examining colonies grown on agar plates. Pathogens detected during the initial screening were further confirmed by PCR and DNA sequencing. Infection rates for Trichomonas, Salmonella, and Listeria were 9%, 17%, and 5%, respectively. The distributions of infection rates across habitats (i.e., rural, exurban, rural) did not differ significantly from the expected null distributions for any of the three pathogens; however, the data suggested some interesting patterns that should be confirmed with a larger dataset. Infection rates for Trichomonas and Salmonella were highest at the suburban sites, whereas the infection rate for Listeria was highest at the rural site. Feeder birds were more likely to be infected by all three pathogens than non-feeder birds. Small sample sizes prevent definitive conclusions regarding variation in infection rates along the suburban to rural gradient, but the results suggest that pathogens followed the predicted patterns. For many of the bird species sampled, this study presents the first report of infection rates by these three pathogens in wild populations.

High prevalence of Trichomonas gallinae in wild columbids across western and southern Europe

Background

Avian trichomonosis is known as a widespread disease in columbids and passerines, and recent findings have highlighted the pathogenic character of some lineages found in wild birds. Trichomonosis can affect wild bird populations including endangered species, as has been shown for Mauritian pink pigeons Nesoenas mayeri in Mauritius and suggested for European turtle doves Streptopelia turtur in the UK. However, the disease trichomonosis is caused only by pathogenic lineages of the parasite Trichomonas gallinae. Therefore, understanding the prevalence and distribution of both potentially pathogenic and non-pathogenic T. gallinae lineages in turtle doves and other columbids across Europe is relevant to estimate the potential impact of the disease on a continental scale.

Results

We examined 281 samples from four wild columbid species for Trichomonas infection and determined the genetic lineages. The overall prevalence was 74%. There were significant differences between the species (P = 0.007). The highest prevalence was found in stock doves Columba oenas (86%, n = 79) followed by wood pigeons Columba palumbus (70%, n = 61) and turtle doves (67%, n = 65), while three of five collared doves Streptopelia decaocto (60%) were infected. We found seven different lineages, including four lineages present in columbids in the UK, one lineage already described from Spain and three new lineages, one of those found in a single turtle dove migrating through Italy and another one found in a breeding stock dove. Stock doves from Germany and collared doves from Malta were infected with a potentially pathogenic lineage (lineage A/B), which is known to cause lesions and mortality in columbids, raptors and finches.

Conclusions

Generally, turtle doves showed high prevalence of Trichomonas infection. Furthermore, the potentially pathogenic lineage A/B (or genotype B according to previous literature) was found in a recovering stock dove population. Both findings are worrying for these columbid species due to the occasional epidemic character of trichomonosis, which can have severe negative effects on populations.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-017-2170-0) contains supplementary material, which is available to authorized users.

Avian trichomonosis in spotted owls (Strix occidentalis): Indication of opportunistic spillover from prey

Avian trichomonosis, caused by the flagellated protozoan parasite Trichomonas gallinae, has variable pathogenicity among bird species ranging from asymptomatic infections to severe disease periodically manifesting in epidemic mortality. Traditionally, columbids are identified as highly susceptible to infection with occasional spillover into raptors that prey on infected birds. We identified avian trichomonosis in two dead California spotted owls (Strix occidentalis occidentalis) and three dead northern spotted owls (S. o. caurina) in California during 2011–2015; infection was confirmed in four owls by PCR. Pathologic lesions associated with trichomonosis in the owls included caseonecrotic lesions of the upper palate accompanied by oropharyngitis, cellulitis, myositis, and/or sinusitis. Spotted owls are known to mainly feed on small mammals; therefore, the source of infection as well as the significance of the disease in spotted owls is unclear. These owl trichomonosis cases coincided temporally and spatially with three trichomonosis epidemics in band-tailed pigeons (Patagioenas fasciata monilis). The same parasite, T. gallinae subtype A2, was isolated from the spotted owls and band-tailed pigeons, suggesting the owls became infected when opportunistically feeding on pigeons during mortality events. Avian trichomonosis is an important factor in the decline of the Pacific Coast band-tailed pigeon population with near-annual mortality events during the last 10 years and could have conservation implications for raptor species at risk, particularly those that are facing multiple threats.

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Band-tailed pigeons evaluated for trichomonad infections during mortality events.

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Spotted owls evaluated for trichomonad infections coinciding with mortality events.

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Trichomonads characterized using ITS1/5.8S rRNA/ITS2 and Fe-hydrogenase loci.

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Trichomonas gallinae subtype A2 was predominant parasite in both pigeons and owls.

Molecular characterization of Trichomonas gallinae isolates recovered from the Canadian Maritime provinces’ wild avifauna reveals the presence of the genotype responsible for the European finch trichomonosis epidemic and additional strains

Finch trichomonosis, caused by Trichomonas gallinae, emerged in the Canadian Maritime provinces in 2007 and has since caused ongoing mortality in regional purple finch (Carpodacus purpureus) and American goldfinch (Carduelis tristis) populations. Trichomonas gallinae was isolated from (1) finches and rock pigeons (Columbia livia) submitted for post-mortem or live-captured at bird feeding sites experiencing trichomonosis mortality; (2) bird seed at these same sites; and (3) rock pigeons live-captured at known roosts or humanely killed. Isolates were characterized using internal transcribed spacer (ITS) region and iron hydrogenase (Fe-hyd) gene sequences. Two distinct ITS types were found. Type A was identical to the UK finch epidemic strain and was isolated from finches and a rock pigeon with trichomonosis; apparently healthy rock pigeons and finches; and bird seed at an outbreak site. Type B was obtained from apparently healthy rock pigeons. Fe-hyd sequencing revealed six distinct subtypes. The predominant subtype in both finches and the rock pigeon with trichomonosis was identical to the UK finch epidemic strain A1. Single nucleotide polymorphisms in Fe-hyd sequences suggest there is fine-scale variation amongst isolates and that finch trichomonosis emergence in this region may not have been caused by a single spill-over event.

Intra-annual patterns in adult band-tailed pigeon survival estimates

Context The band-tailed pigeon (Patagioenas fasciata) is a migratory species occurring in western North America with low recruitment potential and populations that have declined an average of 2.4% per year since the 1960s. Investigations into band-tailed pigeon demographic rates date back to the early 1900s, and existing annual survival rate estimates were derived in the 1970s using band return data. Aims The primary purpose of the paper was to demonstrate that the apparent paradox between band-tailed pigeon population dynamics (long-term steady decline) and breeding season survival rates (very high) can be explained by changes in survival probability during the remainder of the year. Methods We trapped Pacific coast band-tailed pigeons during two separate periods: we equipped pigeons with very high frequency (VHF) radio-transmitters in 1999–2000 (1999 = 20; 2000 = 34); and outfitted pigeons with solar powered platform transmitting terminal (PTT) transmitters in 2006–08 (n = 20). We used known fate models to estimate annual survival rates and seasonal survival variation among four periods based on an annual behavioural cycle based on phenological events (nesting, autumn migration, winter and spring migrations). We used model averaged parameter estimates to account for model selection uncertainty. Key results Neither body condition nor sex were associated with variation in band-tailed pigeon survival rates. Weekly survival during the nesting season did not differ significantly between VHF-marked (0.996; CI = 0.984–0.999) and PTT-marked pigeons (0.998; CI = 0.990–1.00). Model averaged annual survival of PTT-marked pigeons was 0.682 (95% CI = 0.426–0.861) and was similar to annual survival estimated in previous studies using band return data. Survival probability was lowest during both migration periods and highest during the nesting period. Conclusions Our survival estimates are consistent with those of prior studies and suggest that mortality risk is greatest during migration. Weekly survival probability during winter was nearly the same as during the nesting season; however, winter was the longest period and survival throughout winter was lower than other seasons. Implications We present the first inter-seasonal analysis of survival probability of the Pacific coast race of band-tailed pigeons and illustrate important temporal patterns that may influence future species management including harvest strategies and disease monitoring.