Necrotic ingluvitis in wild finches

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.

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.

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.

Multilocus Analysis Resolves the European Finch Epidemic Strain of Trichomonas gallinae and Suggests Introgression from Divergent Trichomonads

In Europe, Trichomonas gallinae recently emerged as a cause of epidemic disease in songbirds. A clonal strain of the parasite, first found in the United Kingdom, has become the predominant strain there and spread to continental Europe. Discriminating this epidemic strain of T. gallinae from other strains necessitated development of multilocus sequence typing (MLST). Development of the MLST was facilitated by the assembly and annotation of a 54.7 Mb draft genome of a cloned stabilate of the A1 European finch epidemic strain (isolated from Greenfinch, Chloris chloris, XT-1081/07 in 2007) containing 21,924 protein coding genes. This enabled construction of a robust 19 locus MLST based on existing typing loci for Trichomonas vaginalis and T. gallinae. Our MLST has the sensitivity to discriminate strains within existing genotypes confidently, and resolves the American finch A1 genotype from the European finch epidemic A1 genotype. Interestingly, one isolate we obtained from a captive black-naped fruit dove Ptilinopsus melanospilus, was not truly T. gallinae but a hybrid of T. gallinae with a distant trichomonad lineage. Phylogenetic analysis of the individual loci in this fruit dove provides evidence of gene flow between distant trichomonad lineages at 2 of the 19 loci examined and may provide precedence for the emergence of other hybrid trichomonad genomes including T. vaginalis.

Tetratrichomonas and Trichomonas spp.-Associated Disease in Free-Ranging Common Eiders ( Somateria mollissima) from Wellfleet Bay, MA and Description of ITS1 Region Genotypes

During an outbreak of Wellfleet Bay virus (WFBV) in common eiders ( Somateria mollissima) from the Cape Cod region of Massachusetts, several birds were diagnosed with trichomonosis consisting of multiple trichomonad species. Six birds were examined, with trichomonads found in ceca in four birds and associated typhlitis in three of these four birds. PCR and DNA sequencing utilizing trichomonad-specific primers targeting the ITS1 region of the ribosomal DNA (rDNA) revealed the presence of Tetratrichomonas gallinarum in the gastrointestinal tracts of five birds and Trichomonas spp. in the livers of two birds, one of which had a dual Te. gallinarum-Trichomonas gallinae infection. Sequence analysis revealed no variation between Te. gallinarum sequences whereas the ITS1 sequences obtained from the other Trichomonas spp. demonstrated the presence of multiple genotypes. One sequence had 100% identity to a Trichomonas sp. previously isolated from a Cooper's hawk ( Accipiter cooperii) and the other sequence was 100% identical to a previously described Tr. gallinae isolate obtained from a Pacific Coast band-tailed pigeon ( Patagioenas fasciata monilis). These findings suggest Te. gallinarum and other Trichomonas spp. possibly contributed to morbidity and mortality in this species. Furthermore, to the authors' knowledge, this is the first report of trichomonad-associated disease in a free-ranging sea duck.

Improved subtyping affords better discrimination of Trichomonas gallinae strains and suggests hybrid lineages

Trichomonas gallinae is a protozoan pathogen that causes avian trichomonosis typically associated with columbids (canker) and birds of prey (frounce) that predate on them, and has recently emerged as an important cause of passerine disease. An archived panel of DNA from North American (USA) birds used initially to establish the ITS ribotypes was reanalysed using Iron hydrogenase (FeHyd) gene sequences to provide an alphanumeric subtyping scheme with improved resolution for strain discrimination. Thirteen novel subtypes of T. gallinae using FeHyd gene as the subtyping locus are described. Although the phylogenetic topologies derived from each single marker are complementary, they are not entirely congruent. This may reflect the complex genetic histories of the isolates analysed which appear to contain two major lineages and several that are hybrid. This new analysis consolidates much of the phylogenetic signal generated from the ITS ribotype and provides additional resolution for discrimination of T. gallinae strains. The single copy FeHyd gene provides higher resolution genotyping than ITS ribotype alone. It should be used where possible as an additional, single-marker subtyping tool for cultured isolates.

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.

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.

Multi-locus sequence typing confirms the clonality ofTrichomonas gallinaeisolates circulating in European finches

In recent years,Trichomonas gallinaeemerged as the causative agent of an infectious disease of passerine birds in Europe leading to epidemic mortality of especially greenfinchesChloris chlorisand chaffinchesFringilla coelebs. After the appearance of finch trichomonosis in the UK and Fennoscandia, the disease spread to Central Europe. Finch trichomonosis first reached Austria and Slovenia in 2012. In the present study the genetic heterogeneity ofT. gallinaeisolates from incidents in Austria and Slovenia were investigated and compared with British isolates. For this purpose comparative sequence analyses of the four genomic loci ITS1-5.8S-ITS2, 18S rRNA,rpb1and Fe-hydrogenase were performed. The results corroborate that one clonalT. gallinaestrain caused the emerging infectious disease within passerine birds and that the disease is continuing to spread in Europe. The same clonal strain was also found in a columbid bird from Austria. Additionally, the present study demonstrates clearly the importance of multi-locus sequence typing for discrimination of circulatingT. gallinaestrains.

The emergence and spread of finch trichomonosis in the British Isles

Finch trichomonosis, caused by the protozoal parasite Trichomonas gallinae, was first recognized as an emerging infectious disease of British passerines in 2005. The first year of seasonal epidemic mortality occurred in 2006 with significant declines of greenfinch Carduelis chloris and chaffinch Fringilla coelebs populations. Here, we demonstrate that large-scale mortality, principally of greenfinch, continued in subsequent years, 2007-2009, with a shifting geographical distribution across the British Isles over time. Consequent to the emergence of finch trichomonosis, the breeding greenfinch population in Great Britain has declined from ca 4.3 million to ca 2.8 million birds and the maximum mean number of greenfinches (a proxy for flock size) visiting gardens has declined by 50 per cent. The annual rate of decline of the breeding greenfinch population within England has exceeded 7 per cent since the initial epidemic. Although initially chaffinch populations were regionally diminished by the disease, this has not continued. Retrospective analyses of disease surveillance data showed a rapid, widespread emergence of finch trichomonosis across Great Britain in 2005 and we hypothesize that the disease emerged by T. gallinae jumping from columbiforms to passeriforms. Further investigation is required to determine the continuing impact of finch trichomonosis and to develop our understanding of how protozoal diseases jump host species.

Evidence of spread of the emerging infectious disease, finch trichomonosis, by migrating birds

Finch trichomonosis emerged in Great Britain in 2005 and led to epidemic mortality and a significant population decline of greenfinches, Carduelis chloris and chaffinches, Fringilla coelebs, in the central and western counties of England and Wales in the autumn of 2006. In this article, we show continued epidemic spread of the disease with a pronounced shift in geographical distribution towards eastern England in 2007. This was followed by international spread to southern Fennoscandia where cases were confirmed at multiple sites in the summer of 2008. Sequence data of the ITS1/5.8S/ITS2 ribosomal region and part of the small subunit (SSU) rRNA gene showed no variation between the British and Fennoscandian parasite strains of Trichomonas gallinae. Epidemiological and historical ring return data support bird migration as a plausible mechanism for the observed pattern of disease spread, and suggest the chaffinch as the most likely primary vector. This finding is novel since, although intuitive, confirmed disease spread by migratory birds is very rare and, when it has been recognised, this has generally been for diseases caused by viral pathogens. We believe this to be the first documented case of the spread of a protozoal emerging infectious disease by migrating birds.

Clinical signs and histopathologic findings associated with a newly recognized protozoal disease (Trichomonas gallinae) in free-ranging house finches (Carpodacus mexicanus)

This paper describes the clinical signs and histopathologic findings associated with an emergent disease associated with Trichomonas gallinae infections in free-ranging house finches (Carpodacus mexicanus) in California. Wet mounts were necessary to detect T. gallinae infections in house finches because classical clinical presentation, such as caseous stomatitis or ingluvitis, occurred in < 25% of cases. Early detection was instrumental in preventing trichomonosis outbreaks in a high-density nursery (P < 0.0001). Detection before onset of clinical signs was critical. Despite treatment, approximately 95% of house finches died within 24 hr of displaying signs of illness. In contrast, 58% of T. gallinae-positive house finches housed in a nursery survived if they received treatment before onset of clinical signs. Recurrent protozoal shedding in survivors was not evident.

Emerging infectious disease leads to rapid population declines of common British birds

Emerging infectious diseases are increasingly cited as threats to wildlife, livestock and humans alike. They can threaten geographically isolated or critically endangered wildlife populations; however, relatively few studies have clearly demonstrated the extent to which emerging diseases can impact populations of common wildlife species. Here, we report the impact of an emerging protozoal disease on British populations of greenfinch Carduelis chloris and chaffinch Fringilla coelebs, two of the most common birds in Britain. Morphological and molecular analyses showed this to be due to Trichomonas gallinae. Trichomonosis emerged as a novel fatal disease of finches in Britain in 2005 and rapidly became epidemic within greenfinch, and to a lesser extent chaffinch, populations in 2006. By 2007, breeding populations of greenfinches and chaffinches in the geographic region of highest disease incidence had decreased by 35% and 21% respectively, representing mortality in excess of half a million birds. In contrast, declines were less pronounced or absent in these species in regions where the disease was found in intermediate or low incidence. Also, populations of dunnock Prunella modularis, which similarly feeds in gardens, but in which T. gallinae was rarely recorded, did not decline. This is the first trichomonosis epidemic reported in the scientific literature to negatively impact populations of free-ranging non-columbiform species, and such levels of mortality and decline due to an emerging infectious disease are unprecedented in British wild bird populations. This disease emergence event demonstrates the potential for a protozoan parasite to jump avian host taxonomic groups with dramatic effect over a short time period.

Salmonellosis in garden birds in Scotland, 1995 to 2008: geographic region, Salmonella enterica phage type and bird species

Salmonellosis was diagnosed in garden birds from 198 incidents in Scotland between September 1995 and August 2008. Salmonellosis was essentially a disease of finches in the north of Scotland, but in the south of Scotland it was also a problem in house sparrows. Almost all of the incidents were caused by Salmonella Typhimurium phage types 40 or 56/variant, but regional variation in phage types was observed. In the north of Scotland, one phage type (DT 40) predominated, but in the south of Scotland two phage types were commonly isolated (DTs 40 and 56/variant, with the latter the more common of the two phage types). This regional difference was statistically significant for salmonellosis in greenfinches, chaffinches and 'other garden birds', but not for house sparrows. Different temporal patterns for different species of bird and different phage types were also observed within regions. These findings suggest that the epidemiology of salmonellosis in garden birds varies depending on the phage type of Salmonella and the species of garden bird, with additional regional differences depending on the wild bird populations and the phage types of Salmonella in circulation. An awareness of these differences will help when formulating guidelines aimed at reducing the impact of salmonellosis in garden birds.