A clonal strain of Trichomonas gallinae is the aetiologic agent of an emerging avian epidemic disease (original) (raw)
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Molecular identity and heterogeneity of trichomonad parasites in a closed avian population
2007
Columbids (pigeons and doves) are the primary host of Trichomonas gallinae, the flagellate protozoon which causes avian trichomoniasis, a widespread, often lethal disease. Although predominantly apathogenic, the organism is paradigmatic for the study of strain-specific virulence, with some strains causing greater than 75% mortality and epizootic die-offs in wildlife populations. In recent years, research on this important emerging pathogen has been neglected and genetic variation within the parasite has not hitherto been investigated. The pink pigeon (Columba mayeri), endemic to Mauritius and one of the world's rarest pigeons, suffers high levels of nestling/fledgling mortality from trichomoniasis. As a closed oceanic island population with recorded life-history parameters for all birds, this species represents a unique resource for the study of this hostparasite interaction. To investigate genetic variation within T. gallinae in Mauritian columbids, isolates were collected from pink pigeons and another widespread species, the Madagascar turtle-dove (Streptopelia picturata). Comparison of the 5.8S region of rDNA and surrounding internally transcribed spacer regions (ITS) showed no sequence variation between isolates or with an unrelated but previously sequenced T. gallinae isolate (Genbank). This confirmed all 24 isolates as T. gallinae, and defined this section of the genome as a good species marker. In contrast, Random Amplified Polymorphic DNA (RAPD) analysis of the isolates revealed considerable genotypic variation between isolates. RAPD genotypes appeared to correlate with geographic distribution and host species, suggesting inter-species transmission and rapid host adaptation by the parasite. #
The finch epidemic strain of Trichomonas gallinae is predominant in British non-passerines
Parasitology, 2013
Avian trichomonosis, caused by the flagellated protozoan Trichomonas gallinae, is a recently emerged infectious disease of British passerines. The aetiological agent, a clonal epidemic strain of the parasite, has caused unprecedented finch mortality and population-level declines in Britain and has since spread to continental Europe. To better understand the potential origin of this epidemic and to further investigate its host range, T. gallinae DNA extracts were collected from parasite culture and tissue samples from a range of avian species in Britain. Sequence typing at the ITS1/5.8S rRNA/ITS2 region resolved three distinct ITS region types circulating in free-ranging British birds. Subtyping by sequence analyses at the Fe-hydrogenase gene demonstrated further strain variation within these ITS region types. The UK finch epidemic strain was preponderant amongst columbids sampled, however, wide strain diversity was encountered in isolates from a relatively small number of pigeons, suggesting further strains present in columbid populations across the UK are yet to be identified. Fe-hydrogenase gene sequence data in isolates from birds of prey with disease were predominantly identical to the UK finch epidemic strain, demonstrating its presence as a virulent strain in UK birds of prey since at least 2009.
Genome Biology and Evolution, 2019
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.
Parasitology, 2016
Finch trichomonosis is an emerging infectious disease affecting European passerines caused by a clonal strain of Trichomonas gallinae. Migrating chaffinches (Fringilla coelebs) were proposed as the likely vector of parasite spread from Great Britain to Fennoscandia. To test for such parasite carriage, we screened samples of oesophagus/crop from 275 Apodiform, Passeriform and Piciform birds (40 species) which had no macroscopic evidence of trichomonosis (i.e. necrotic ingluvitis). These birds were found dead following the emergence of trichomonosis in Great Britain, 2009-2012, and were examined post-mortem. Polymerase chain reactions were used to detect (ITS1/5·8S rRNA/ITS2 region and single subunit rRNA gene) and to subtype (Fe-hydrogenase gene) T. gallinae. Trichomonas gallinae was detected in six finches [three chaffinches, two greenfinches (Chloris chloris) and a bullfinch (Pyrrhula pyrrhula)]. Sequence data had 100% identity to the European finch epidemic A1 strain for each spec...
High prevalence of Trichomonas gallinae in wild columbids across western and southern Europe
Parasites & vectors, 2017
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. 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). T...
Avian Pathology, 2019
Outbreaks of avian trichomonosis are being reported worldwide meanwhile the genetic and virulence variations are under investigation. In this study, the occurrence and genetic variability of oral or fecal trichomonads among various avian species were investigated. Samples obtained from either the oropharyngeal cavity, crop/esophagus, droppings/cloaca, or conjunctival swabs of avian species were inspected for flagellates. Phylogenetic analysis of partial ITS1-5.8s rRNA-ITS2 sequences from selected samples was performed to investigate the genetic diversity of the isolates. Investigation of 737 birds, revealed the infection rate of 15.7% in the upper gastrointestinal tract, 7.3% in the fecal samples and 0.7% involvement of the conjunctiva. Phylogenetic analysis of partial ITS1-5.8s rRNA-ITS2 sequences from selected samples, identified genotypes A and B of T. gallinae and genogroups A-C and E of Tetratrichomonas gallinarum. Novel ITS genotype of intestinal trichomonads was also detected in hooded crow (Corvus cornix) and common mynah (Acridotheres tristis). In the present study, in addition to Columbiformes and Falconiformes, trichomonads were detected in Passeriformes and Galliformes with the involvement of organs other than the gastrointestinal tract. Genotype A T. gallinae has been detected in domestic pigeons (Columba livia domestica), a laughing dove (Spilopelia senegalensis), a common kestrel (Falco tinnunculus), a budgerigar (Melopsittacus undulates), and a canary (Serinus canaria). Distinct genotype B has been detected in a common mynah and a budgerigar. Genogroups A-C of T. gallinarum was also demonstrated in Galliformes and Anseriformes. Furthermore, two novel trichomonad ITS genotypes were detected in hooded crows and a common mynah warranting detailed multi-loci molecular analysis.
Trichomonad parasite infection in four species of Columbidae in the UK
Parasitology, 2013
SUMMARYTrichomonas gallinaeis an emerging pathogen in wild birds, linked to recent declines in finch (Fringillidae) populations across Europe. Globally, the main hosts for this parasite are species of Columbidae (doves and pigeons); here we carry out the first investigation into the presence and incidence ofTrichomonasin four species of Columbidae in the UK, through live sampling of wild-caught birds and subsequent PCR. We report the first known UK cases ofTrichomonasinfection in 86% of European Turtle DovesStreptopelia turtursampled, along with 86% of Eurasian Collared DovesStreptopelia decaocto, 47% of WoodpigeonsColumba palumbusand 40% of Stock DovesColumba oenas. Birds were more likely to be infected if the farm provided supplementary food for gamebirds. We found three strains ofT. gallinaeand one strain clustering within theTrichomonas tenaxclade, not previously associated with avian hosts in the UK. OneT. gallinaestrain was identical at the ITS/5.8S/ITS2 ribosomal region to th...
To get sick or not to get sick—Trichomonas infections in two Accipiter species from Germany
Parasitology Research, 2021
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 an...
Avian pathology : journal of the W.V.P.A, 2014
Oropharyngeal trichomonad isolates of wild birds from Spain were studied. A total of 1688 samples (1214 of predator birds and 474 of prey species) from wildlife recovery centres and scientific bird-ringing campaigns were analysed from 2011 to 2013. The overall infection prevalence was 20.3% (11.4% in predator birds and 43.3% in prey species). Pathognomonic lesions were present in 26% of the infected birds (57.3% in predator birds and 4.9% in prey species). The most commonly parasitized species were the goshawk (Accipiter gentilis, 74.5%) and the rock pigeon (Columba livia, 79.4%). Host species in which the parasite has not been previously analysed by polymerase chain reaction and sequencing in Spain are also reported: Columba palumbus, Streptopelia turtur, Pica pica, A. gentilis, Accipiter nisus, Asio otus, Bubo bubo, Buteo buteo, Circus aeruginosus, Circus cyaneus, Falco naumanni, Falco peregrinus, Neophron percnopterus, Otus scops, Pernis apivorus and Strix aluco. Sequence analysi...