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

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.

Supplementation of exogenous bile acids improve antitrichomonal activity and enhance intestinal health in pigeon (Columba livia)

The study investigated the effects of supplementation of bile acids in drinking water on antitrichomonal activity, growth performance, immunity and microbial composition of pigeon. A total of 180 pairs of White King parent pigeons were randomly assigned to 5 treatments of 6 replications with 6 pairs of parent pigeons and 12 squabs in each replicate. The control (CON) group drank water without any additions. The metronidazole (MTZ) group drank water with 500 μg/mL metronidazole for 7 d and without any additions in other days. The else groups drank water with 500, 750, and 1,250 μg/mL bile acid (BAL, BAM, BAH) for 28 d. The results showed that Trichomonas gallinae (T. gallinae) in MTZ, BAL, BAM, and BAH groups were lower than that in CON group at 14, 21, and 28 d of parent pigeons (P < 0.05) and at 21 and 28 d of squabs (P < 0.05). Albumin and alanine transaminase in CON group were higher than those in MTZ, BAL, and BAH groups (P < 0.05). The levels of soluble CD8 were higher in MTZ and BAH groups compared with CON group (P < 0.05). The lesions in oral mucosa, thymus, liver, and spleen tissues of CON group could be observed. Abundance-based coverage estimator (ACE) index in BAH group was higher than that in CON and MTZ groups. Simpson index in CON and BAH groups was higher than MTZ group (P < 0.05). Lactobacillus was the highest colonized colonic bacteria in genera that were 77.21, 91.20, and 73.19% in CON, MTZ, and BAH, respectively. In conclusion, drinking water supplemented with 500, 750, and 1,250 μg/mL bile acid could inhibit growth of T. gallinae in both parent pigeons and squabs. Squabs infected with T. gallinae in control group had higher mortality rate and more serious tissue lesions. Squabs in bile acids treated group had more sCD8 in serum and abundant intestinal morphology. Bile acids could be an efficient drinking supplements to inhibit T. gallinae and improve pigeon adaptive immunity and intestinal health.

Molecular epidemiological study of Trichomonas gallinae focusing on central and southeastern Europe

Trichomonas gallinae is a geographically widespread protozoan parasite of birds. In this study, oropharyngeal swab samples were collected in Hungary and Romania from 99 columbiform birds, including 76 feral pigeons (Columba livia domestica: 42 kept for racing, 32 with urban and two with rural habitat), four common wood pigeons (C. palumbus), 16 ring doves (Streptopelia risoria) and three Eurasian collared doves (S. decaocto). These samples were analyzed for the presence of T. gallinae using molecular methods. Racing feral pigeons had significantly higher prevalence of T. gallinae infection than urban feral pigeons. The rate of PCR-positivity was the highest among wood pigeons and ring doves. Based on 18S rRNA gene, T. gallinae was the most heterogenous among racing feral pigeons sampled in a trading-breeding place. Clinical signs were associated with only one 18S rRNA gene subtype. The most divergent 18S rRNA gene subtype, Trichomonas sp. Hu-TG37 clustered with T. canistomae and T. tenax and represents probably a new species. To our knowledge, this is the first report on the genetic diversity of T. gallinae in the southeastern European region. The results suggest that most detected T. gallinae 18S rRNA gene subtypes are not host-specific and do not cause clinical signs. The highest number of 18S rRNA gene subtypes was demonstrated among racing feral pigeons. Significantly more captive than free-living columbiform birds had T. gallinae infection. These data highlight the importance of epizootic monitoring of the genetic diversity and presence of T. gallinae in trading-breeding places of pigeons and doves.

A new duplex real-time PCR for simultaneous detection and differentiation of Tetratrichomonas gallinarum and Trichomonas gallinae

Tetratrichomonas gallinarum and Trichomonas gallinae are pathogenic avian parasites that infect a wide range of bird species. The pathologic potential of T. gallinarum is controversial, whereas T. gallinae causes disease in many avian species. Infections are often asymptomatic in doves and pigeons; thus, columbids are presumed to represent the natural hosts for trichomonads. The detection of T. gallinarum and T. gallinae is based on direct microscopic observation or a conventional PCR assay. Microscopy is not very sensitive, and identification of the trichomonads at the genus or species level is not possible. Conventional PCR assays have been developed primarily for phylogenetic studies, which detect a wide range of Trichomonas spp. but do not allow their differentiation. We developed a duplex real-time PCR (rtPCR) assay for the simultaneous detection and differentiation of T. gallinarum and T. gallinae. We found that the rtPCR assay detected 10² plasmid DNA copies of T. gallinarum and as few as 10¹ plasmid DNA copies of T. gallinae.

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.

High-Throughput Sequencing of faeces provides evidence for dispersal of parasites and pathogens by migratory waterbirds

Examination of faecal material has demonstrated how a broad range of organisms are distributed by bird movements. Such research has largely focused on dispersal of plant seeds by frugivores and of freshwater organisms by waterbirds. However, with few exceptions (e.g. avian influenza, Ebola virus), there is a dearth of evidence for transport of parasites and pathogens. High-throughput sequencing methods now provide a powerful means of addressing this knowledge gap by elucidating faecal contents in unprecedented detail. We collected faeces excreted by a range of migratory waterbirds in south-west Spain and pooled faecal DNA to create libraries reflective of feeding behavior. We created sets of libraries using high-throughput metagenomic and amplicon sequencing. For the latter we employed two sets of primers to broadly target the V4 region of the 18S rRNA gene (one set amplifying the region across all eukaryotes, the other excluding amplification of metazoans). Libraries revealed a wide diversity of eukaryotes, including parasites of the faecal producers themselves, parasites of food items, or those incidentally ingested. We also detected novel microbial eukaryotic taxa and found that parasite assemblage profiles were relatively distinct. Comparing the performance of the methods used supports their joint use for future studies of diversity and abundance. Because viable stages of many parasites are likely to be present in faeces, our results suggest significant levels of bird-mediated dispersal of parasites (both from avian and other hosts). Our methods revealed much hidden biodiversity, and allowed identification of the individuals who produced the faecal samples to species level, facilitating the study of interaction networks.

Antibiotic treatment increases yellowness of carotenoid feather coloration in male greenfinches (Chloris chloris)

Carotenoid plumage coloration is an important sexually selected trait in many bird species. However, the mechanisms ensuring the honesty of signals based on carotenoid pigments remain unclear. It has recently been suggested that intestinal integrity, which is affected by gut parasites and microbiota and influences nutrient absorption and acquisition, mediates the relationship between carotenoid ornamentation and individual quality. Here, we test whether carotenoid plumage coloration in greenfinches (Chloris chloris) is affected by the treatment of an antibiotic or an antiparasitic drug. We captured wild greenfinches (N = 71) and administered anticoccidial medication toltrazuril (TOLTRA) to one group, antibiotic metronidazole (METRO) to the second group to target trichomonosis, and the third group received no medication. In the METRO group, feathers grown during the experiment had significantly higher chroma of yellow parts, but there was no effect of TOLTRA on feather chroma. The results suggest that METRO increased the efficiency of carotenoid modification or deposition to the feathers rather than nutrient acquisition and/or freed energy resources that could be invested in coloration. Alternatively, though not measured, METRO might have affected microbial community and host physiology as microbial metabolites can modulate mitochondrial and immune function.

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.

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.