Trichomonad infection in endemic and introduced columbids in the Seychelles

Island endemic avifaunas face many threats, including the now well-documented impacts of pathogens. The impacts of pathogens on the endemic Seychelles avifauna, however, have been little studied. The protozoan parasite Trichomonas gallinae has been shown to reduce survival and reproductive success of the endemic Pink Pigeon Columba mayeri on the nearby island of Mauritius. I investigated trichomonad infection prevalence and pathogenicity in endemic Seychelles Blue Pigeons, Alectroenas pulcherrima, and two introduced species of columbid, the Madagascar Turtle-dove, Streptopelia picturata, and the Barred Ground Dove, Geopelia striata, on the Seychelles island of Mahé during September-October 2007. I asked whether: 1) trichomonad infections occur in these species; 2) prevalence varies among species; and 3) birds show any signs of pathogenicity consistent with tricho-monosis. I use the results to assess the potential threat of this pathogen to A. pulcherrima. All three species were infected with trichomonads, and the overall prevalence was 27.5%. Alectroenas pulcherrima had higher prevalence (47.1%) than the two introduced species combined (24.3%). No infected individuals showed any signs of disease. These findings suggest that trichomonad parasites should be considered as a potential disease threat to the A. pulcherrima population.     

Prevalence of Leucocytozoon marchouxi in the endangered Pink Pigeon Columba mayeri

The prevalence and density of infection with the haematozoan parasite Leucocytozoon marchouxi was studied in captive and free-living Pink Pigeons Columba mayeri on Mauritius between 1994 and 2002. Blood smears from adults, juveniles and squabs were screened. Overall prevalence of L. marchouxi was 30% and there were age class and year differences. Younger birds (≤ 1 year) were more often infected and had a higher density of infection than did older birds. High parasite levels were found in 6% of birds, all but one of which were less than 1 year old. Leucocytozoonosis has been recorded elsewhere in 20 out of 45 Pink Pigeons post-mortem and was the primary cause of death in 15 birds. However, we detected no significant difference in the survival of infected and uninfected birds examined in this study, suggesting that only subclinical infections were detected and any mortality was probably due to additional contributing factors such as concurrent disease and food shortages. A smaller sample of smears from other columbid species was collected to examine their role as reservoir hosts. The parasite was probably introduced to Mauritius with exotic columbids, which may be partially resistant, but the Pink Pigeon has acquired sufficient immunity now to be a maintenance host for the parasite.     

Trichomonas gallinae in wintering Common Wood Pigeons Columba palumbus in Spain

We studied the prevalence and potential subclinical effects of infestation by Trichomonas gallinae in 91 hunter-harvested Common Wood Pigeons Columba palumbus from northern ( n  = 30) and southern ( n  = 61) Spain during the winter period. All animals were measured, sexed, aged, necropsied and their organs were weighed. Infestation with T. gallinae was diagnosed using three different methods: direct inspection for the presence of lesions, direct microscopic observation and culture. Of the sampled birds, 34.2% were positive for the presence of T. gallinae . Prevalence was significantly higher in adult Wood Pigeons than in the juvenile group, and prevalence was significantly lower in birds sampled from the north. No significant differences in prevalence were found between males and females. Culture was significantly more sensitive than the other methods of diagnosis. Parasitized birds were in poorer body condition, as revealed by their lower body mass and fat reserves. No significant variation could be detected in heart or spleen weight between parasitized and healthy birds. However, juvenile Wood Pigeons in which T. gallinae was detected had a significantly larger bursa of Fabricius. Variations in the prevalence of T. gallinae in Wood Pigeons could be related to migration as well as increased exposure through shared feed and water where these are artificially provided. We also discuss the potential effect of T. gallinae on body condition and the eventual risk for endangered predators through increased exposure to infected prey.     

The incidence of the parasitic disease trichomoniasis and its treatment in reintroduced and wild Pink Pigeons Columba mayeri

The recovery programme for the endangered Pink Pigeon Columba mayeri Prévost, 1843 of Mauritius has involved intensive management to promote rapid population growth. As the Pink Pigeon population has increased in size and distribution, disease problems have emerged that have affected wild and reintroduced birds. Trichomoniasis first appeared in the remnant wild population in 1992, and became established in a reintroduced subpopulation on the offshore island of Ile aux Aigrettes. We aimed to control the disease by treating individuals and, on Ile aux Aigrettes, by routinely treating the population with medicated drinking water. On Ile aux Aigrettes, 49% of squabs were clinically diseased and only 27% of all squabs survived without treatment. Treatment of squabs that were not clinically diseased improved survival from 36 to 82%, suggesting that subclinical infections also affected survival. Subclinical infections were demonstrated by microscopy in 22% of Pink Pigeons and 17% of exotic doves on Ile aux Aigrettes. Clinical disease was observed in 4.5% of adults and 3.1% of juveniles, but more juveniles than adults died from the disease. It is likely that Trichomoniasis and other diseases will continue to affect the Pink Pigeon's recovery and the species may require long-term management to counteract the effects of disease and other limiting factors.     

Primary moult and body-mass of the Cape Turtle Dove Streptopelia capicola,and its abundance relative to the Laughing Dove S. senegalensis,in the Western Cape

Underhill, L.G., Underhill, G.D. & Spottiswoode, C.N. 1999. Primary moult and body-mass of the Cape Turtle Dove Streptopelia capicola, and its abundance relative to the Laughing Dove S. senegalensis, in the Western Cape. Ostrich 70 (3&4): 196–199.

The duration of primary moult of adult Cape Turtle Doves Streptopelia capicola was estimated to be 192 days. 23 November was the estimated mean starting date, with 95% of birds starting within 88 days of this date. The mean body-mass of adults was 148 g and of first-year birds was 130 g. In residential areas, Cape Turtle Doves were trapped less frequently than Laughing Doves S. senegalensis; at most rural sites, Cape Turtle Doves comprised about two-thirds of the catch. On a dairy farm, where doves were attracted to cattle feed, 1 % of doves were Cape Turtle Doves. The emerging pattern is that Laughing Doves predominate at sites where food is provided on a long-term basis.     

Prevalence of Trichomonas gallinae in northern goshawks from the Berlin area of northeastern Germany

In recent years, the northern goshawk (Accipiter gentilis) has colonized suburban and urban areas in Berlin, Germany, and elsewhere in Europe. Because of the high proportion of feral pigeons (Columba livia f. domestica) in their diet, urban goshawks are suspected to have a high infection rate with Trichomonas gallinae. Therefore, from 1998 to 2001, we examined 269 nestlings from 90 nests for infection with T. gallinae by culture of swabs taken from the oropharynx and checked their oropharynx for the presence of caseous lesions indicative of trichomonosis. In 80% of the nest sites (n=90), at least one nestling was infected. The nestling infection rate with T. gallinae was 69.7% (n=33) in 1998, 73.0% (n=89) in 1999, 55.8% (n=77) in 2000, and 62.9% (n=70) in 2001. In total, 65.1% of the northern goshawk nestlings were culture positive for T. gallinae. Prevalence increased with the age of nestlings (chi2=12.4, n=269, df=5, P=0.03) and tended to increase with brood size (chi2=9.345, n=269, df=4, P=0.053). Caseous lesions were present in 12 nestlings (4.5%), but only 10 of these were culture positive for T. gallinae. Two nestlings (0.7%) had large caseous lesions (diameter>1 cm) characteristic of late-stage trichomonosis and died shortly after examination. It is suggested that the combination of a high prevalence of T. gallinae with a low rate of pathologicic changes is the result of an evolutionary-adapted parasite-host relationship.     

Clinical and pathological studies on the Mauritian Pink Pigeon Columba mayeri

Six Pink Pigeons Columba = Nesoenas mayeri from the captive breeding project on Mauritius which showed a range of physical abnormalities were examined clinically and post mortem. Significant findings included a pedal deformity in several birds and cerebellar hypoplasia/aplasia in another. Parasites were not detected and none of the birds showed serum antibodies to Newcastle disease virus, Paramyxovirus or Chlamydia psittaci. The results are of relevance to the captive breeding and management of this endangered species.     

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.     

Analysis of microtubule cytoskeleton distribution using a fluorescent taxoid in two trichomonadid protozoa: Trichomonas gallinae and Tritrichomonas foetus

Trichomonas gallinae and Tritrichomonas foetus are flagellated parasitic protozoa of the upper digestive tract of birds and the urogenital tract of cattle, respectively. Both of these species are important in the veterinary field, due to the fact that they cause significant economic losses. Therefore, we investigated the morphology of these parasites by studying microtubule cytoskeleton organization. FLUTAX-2, an active fluorescent derivative of Taxol, was used in this study. This fluorescent taxoid binds to polymerized alphabeta-tubulin dimers. Our results showed that FLUTAX-2 was able to bind to and stabilize microtubules of intact T. gallinae and T. foetus trophozoites, allowing the microtubular cytoskeleton to be easily observed by fluorescence microscopy. T. foetus and T. gallinae had no differences in their FLUTAX-2 binding profiles. Further studies may allow this technique to be improved, and it may possibly be used as a routine laboratory method for the diagnosis of avian and bovine trichomonosis.     

Trichomonosis in a free-living Stock Dove (<Emphasis Type="Italic">Columba oenas</Emphasis>)

In October 2004, a free-living Stock Dove (Columba oenas) was found infected with Trichomonas spp. in the district of Soest, North Rhine-Westphalia, Germany. A huge buccal nodular lesion caused an occlusion of the esophagus and an external swelling. The bone of the mandibula was already softened and nearly solubilised. The microscopical examination of a wet swab sample from the carcass detected Trichomonas spp. in huge numbers. The morphological diagnosis of the flagellate revealed T. gallinae. Although trichomonosis is well described for several other columbid species around the world, this is probably the first described case of a trichomonosis in a free-living Stock Dove. The possible prevalence in the dove population is discussed.     

Interspecific variation in growth of British pigeons Columbidae

Growth patterns of nestling Collared Doves Streptopetia decaocto , Woodpigeons Columba palumbus , Feral Pigeons C. livia and Stock Doves C. oenas , in Britain were compared. Open-nesting Collared Doves and Woodpigeons left the nest at about 60% of adult weight, hole-nesting Stock Doves at adult weight, and partial hole-nesting Feral Pigeons at an intermediate stage. Other species of pigeons and doves studied to date also fit this pattern. Stock Dove nestlings reared in nest-boxes reached heavier weights and left the nest later than those in more exposed sites. These results were correlated with differential predation pressure on open- versus hole-nesting birds.     

Genetically different clonal isolates of Trichomonas gallinae, obtained from the same bird, can vary in their drug susceptibility, an in vitro evidence

Trichomonas gallinae is a flagellated protozoon which parasitizes in the upper digestive tract of different birds, especially columbiformes (doves and pigeons) and falconiformes. The parasite is also a common inhabitant of the crop of psittacine birds and is frequently detected in budgerigars. The lesions associated with T. gallinae infection of the upper digestive tract range from mild inflammation of the mucosa to large caseous lesions that block the lumen of the oesophagus. Nitroimidazoles are considered to be the drugs of choice for the treatment of trichomonosis. However, only a few studies report the existence of resistant strains of T. gallinae to these drugs. Thus, in the present investigation cloned cultures of T. gallinae obtained from budgerigars and pigeons were analysed for the first time for their in vitro susceptibilities against four 5′-nitroimidazole derivates, including metronidazole, dimetridazole, ronidazole and ornidazole. Significantly different minimal lethal concentrations (MLCs) were observed for them against all four drugs. The lowest MLCs revealed the Trichomonas isolates obtained from two budgerigars, ranging from 2.0 ± 0.3 to 3.0 ± 0.7 μg/ml for metronidazole and dimetridazole, and from 2.0 ± 0.6 to 6.7 ± 1.7 μg/ml for ornidazole and ronidazole. Contrary to this, the highest MLCs were recorded for one Trichomonas isolate obtained from a pigeon, ranging from 83.3 ± 6.7 (for dimetridazole and ronidazole) to 103.3 ± 3.3 μg/ml (for metronidazole and ornidazole). The data obtained for the resistance testing were further compared with already available genetic data of the small subunit rRNA gene sequences and ITS-1, 5.8S rRNA and ITS-2 sequences, indicating a certain correlation between in vitro results and strain relationships.     

Characterization of velogenic Newcastle disease viruses isolated from dead wild birds in Serbia during 2007

Avian paramyxoviruses type 1 or Newcastle disease viruses (NDV) are frequently recovered from wild birds and such isolates are most frequently of low virulence. Velogenic NDV are usually recovered from poultry and only occasionally from wild birds. Five NDV isolates were obtained from carcasses of four wild bird species during 2007 in Serbia: Mallard (Anas platyrhynchos), Eurasian Sparrowhawk (Accipiter nisus), feral Rock Pigeon (Columba livia), and Eurasian Collared Dove (Streptopelia decaocto). All the isolates have a typical fusion protein cleavage site motif of velogenic viruses ((112)R-R-Q-K-R-F(117)). The highest homology (99%) for the nucleotide sequences spanning the M and F gene of the studied isolates was with the genotype VII NDV isolate Muscovy duck/China(Fujian)/FP1/02. Phylogenetic analysis based on a partial F gene sequence showed that the isolates from wild birds cluster together with concurrent isolates from poultry in Serbia within the subgenotype VIId, which is the predominant pathogen involved currently in Newcastle disease outbreaks in poultry worldwide. It is unlikely that the wild birds played an important role in primary introduction or consequent spread of the velogenic NDV to domestic poultry in Serbia, and they probably contracted the virus from locally infected poultry.     

Survival of Trichomonas gallinae in white-winged dove carcasses

Survival of Trichomonas gallinae was examined in white-winged dove (Zenaida asiatica) carcasses to assess whether birds that have been dead up to 8 hr can be sampled reliably for this protozoan. Carcasses of 100 T. gallinae-positive white-winged doves were separated into four groups of 25 birds, representing 2, 4, 6, and 8 hr post mortem sampling intervals and placed into an environmental chamber maintained at 27 C and 75% relative humidity. Live T. gallinae were isolated in 96, 100, 100, and 92% of the carcasses at each of the respective post mortem intervals. The experiment was repeated with another 100 carcasses of T. gallinae-positive white-winged doves placed in the environmental chamber, this time maintained at 27 C and 40% relative humidity. Live T. gallinae occurred in 96, 100, 96, and 100% of the carcasses at each of the respective post mortem intervals. Across both trials, the overall ability to detect positive birds from sampling carcasses up to 8 hrs post mortem was 97%. An a posteriori experiment was conducted in which 23 and 18 carcasses from the second trial were maintained in the environmental chamber at 27 C and 40% relative humidity and resampled at 24 and 48 hr post mortem, respectively. Live trichomonads were isolated from 91 and 44% of the carcasses at 24 and 48 hr, respectively. Results suggest live T. gallinae can be obtained from dove carcasses reliably up to 8 hr and possibly up to 24 hr after host death. The ability for T. gallinae to survive within this time interval can aid wildlife personnel in monitoring this protozoan at hunter check stations or obtaining samples from recently killed birds.     

Molecular characterization of the Trichomonas gallinae morphologic complex in the United States

Forty-two Trichomonas gallinae isolates were molecularly characterized to determine whether isolates differed in genetic sequence of multiple gene targets depending on host species or geographical location. The 5.8S ribosomal RNA (rRNA) and flanking internal transcribed spacer (ITS) gene regions were amplified by polymerase chain reaction, and the sequences were analyzed phylogenetically. The results of the sequence analysis strongly suggest at least 2 species may exist within the T. gallinae morphologic complex. Based on ITS sequences, one group demonstrated high nucleotide identity to the 3 T. gallinae sequences available in GenBank, whereas the second group was more closely related to T. vaginalis (98%) than to T. gallinae (92%). Two common ground-dove (Columbina passerina) isolates shared a 95% identity with T. vaginalis and a 92% identity with T. gallinae and T. tenax. Sequence analysis of both the 18S rRNA and alpha-tubulin genes from a subset of the isolates supports the 5.8S-ITS sequence results. All of the T. vaginalis-like isolates originated from Arizona, California, or Texas, whereas T. gallinae isolates were found in all sampled states. Both T. vaginalis-like and T. gallinae isolates were involved in trichomoniasis outbreaks in California and Arizona.     

河北邢台市森林公园鸟类区系调查初报

2003年3月～2005年4月对邢台市森林公园的鸟类进行了调查,共记录鸟类121种,隶属15目38科.其中留鸟27种,占总数的22.31%;夏候鸟26种,占总数的21.49%;冬候鸟10种,占总数的8.26%;旅鸟58种,占总数的47.94%.山斑鸠（Streptopelia orientalis）、珠颈斑鸠（Streptopelia chinensis）、家燕（Hirundo rustica）、白头鹎（Pycnonotus sinensis）、灰椋鸟（Sturnus cineraceus）、喜鹊（Pica pica）、大山雀（Parus major）、[树]麻雀（Passer montanus）、金翅[雀]（Carduelis sinica）、小鹀（Emberiza pusilla）等10种鸟为公园的优势鸟种.国家Ⅱ级保护重点鸟类11种,河北省重点保护鸟类11种.     

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.     

POPULATION,DIET AND THE ANNUAL CYCLE OF THE LAUGHING DOVE AT BARBERSPAN,PART 3: THE ANNUAL CYCLE

Dean, W. R. J. 1979. Population, diet and the annual cycle of the Laughing Dove at Barbers-pan, Part 3: The annual cycle. Ostrich 50:234-239.

Laughing Doves Streptopelia senegalensis were collected each month from July 1976 to June 1977. In each sample some males and females were breeding. Breeding and primary moult overlapped, and some birds began to moult after starting to breed, and began to breed after starting moult. Adult Laughing Doves require about 120 days to complete primary moult, and juveniles require about 90 days. Weights of moulting birds were not significantly different from those of non-moulting birds, and there were no seasonal trends in the weights of either group. The mean weight of 79 males was 101,6 g and of 39 females was 100,2 g.     

Avian influenza a virus in wild birds in highly urbanized areas

Avian influenza virus (AIV) surveillance studies in wild birds are usually conducted in rural areas and nature reserves. Less is known of avian influenza virus prevalence in wild birds located in densely populated urban areas, while these birds are more likely to be in close contact with humans. Influenza virus prevalence was investigated in 6059 wild birds sampled in cities in the Netherlands between 2006 and 2009, and compared with parallel AIV surveillance data from low urbanized areas in the Netherlands. Viral prevalence varied with the level of urbanization, with highest prevalence in low urbanized areas. Within cities virus was detected in 0.5% of birds, while seroprevalence exceeded 50%. Ring recoveries of urban wild birds sampled for virus detection demonstrated that most birds were sighted within the same city, while few were sighted in other cities or migrated up to 2659 km away from the sample location in the Netherlands. Here we show that urban birds were infected with AIVs and that urban birds were not separated completely from populations of long-distance migrants. The latter suggests that wild birds in cities may play a role in the introduction of AIVs into cities. Thus, urban bird populations should not be excluded as a human-animal interface for influenza viruses.     

Metabolic and thermal physiology of pigeons and doves

Pigeons and doves (Columbidae) are an interesting group to examine for physiological adaptations to climate and diet because this cosmopolitan family comprises more than 300 species that are mostly granivores, although some are specialized frugivores. We determined allometric and phylogenetic effects on body temperature (T(b)), basal metabolic rate (BMR; J h(-1)), and wet thermal conductance (C(wet); J h(-1) C(-1)), and we examined mass (M) and phylogenetically corrected residuals for further effects of climate, diet, and landmass size (mainland or island). Independent contrasts, correlograms, autoregression, and phylogenetic eigenvector regression (PVR) were used to examine phylogenetically related effects. We found a small but significant phylogenetic pattern for body mass of columbids. For T(b), there was no significant effect of mass or phylogeny. There was a significant effect of climate on T(b) and no significant effects of diet or landmass without mass or phylogenetic correction, but after mass and phylogenetic correction, there were no effects of climate, diet, or landmass. For BMR, there was a strong allometric effect, and residuals were significantly lower for arid and tropical species but not for temperate species, compared to predictions for nonpasserine birds. There was a nearly significant autoregressive phylogenetic relationship for BMR parl0;r=0.44), and the strong allometry of BMR remained for independent contrasts (slope=0.731), autoregressive residuals (0.698), and PVR (0.705). Residuals, from regression of autoregression and PVR residuals of M and BMR, were significantly associated with climate: arid pigeons had a lower BMR residual than tropical and temperate pigeons. PVR residuals were significantly affected by landmass (island columbids had a smaller residual than mainland columbids), but autoregression residuals were not. There was no association of autoregression or PVR residuals with diet. For C(wet), there was a strong allometric effect, and residuals for columbids were significantly higher compared to other birds. There was no significant relationship for C(wet) of columbids to climate, diet, or landmass. There was no significant autoregressive or PVR relationship for C(wet), and the strong allometry remained after phylogenetic analysis by independent contrasts (slope=0.501), autoregression (0.509), and PVR (0.514). Residuals from autoregression and PVR were not significantly correlated with climate, diet, or landmass (mainland/island).