Staphylococcosis in captive exotic waterfowl

Pathological and epidemiological findings are presented on Staphylococcus aureus infections in 10 genera of waterfowl kept at the National Zoological Park, USA. Of 2450 Anseriformes necropsied between 1975 and 1992, 43 birds had local or systemic forms of staphylococcosis. Of these 28 (65.1%) were males and 15 (34.9%) were females and most of the deaths occurred between January and June (38 birds, 88.4%). Gross and histopathological lesions were seen in the heart, liver, spleen, kidneys, joints and central nervous system. They were consistent with multiple acute to chronic patterns of inflammatory reaction, ranging from mild to severe necrotizing suppurative exudation. Granulomatous responses were noted in many cases, mainly in the spleen and liver. Amyloidosis occurred concurrently in 14 birds, affecting mainly liver, spleen, kidneys, thyroids, pancreas and adrenals. The epidemiological factors indicate that the most likely route of infection was through the skin, secondary to the naturally aggressive anseriform breeding behaviour. This probably accounted for the greater prevalence of staphylococcosis in the males.     

Susceptibility of wild passerines to subtype H5N1 highly pathogenic avian influenza viruses

Highly pathogenic avian influenza (HPAI) viruses of the H5N1 subtype have spread throughout many areas of Asia, Europe and Africa, and numerous cases of HPAI outbreaks in domestic and wild birds have been reported. Although recent studies suggest that the dissemination of H5N1 viruses is closely linked to the migration of wild birds, information on the potential for viral infection in species other than poultry and waterfowl is relatively limited. To investigate the susceptibility of terrestrial wild birds to infection with H5N1 HPAI viruses, common reed buntings (Emberiza schoeniclus), pale thrushes (Turdus pallidus) and brown-eared bulbuls (Hypsipetes amaurotis) were infected with A/mountain hawk-eagle/Kumamoto/1/07(H5N1) and A/whooper swan/Aomori/1/08(H5N1). The results showed that common reed buntings and brown-eared bulbuls were severely affected by both virus strains (100% mortality). While pale thrushes did not exhibit any clinical signs, seroconversion was confirmed. In common reed buntings, intraspecies-transmission of A/whooper swan/Aomori/1/08 to contact birds was also confirmed. The findings show that three passerine species; common reed buntings, brown-eared bulbuls and pale thrushes are susceptible to infection by H5N1 HPAI viruses, which emphasizes that continued surveillance of species other than waterfowl is crucial for effective monitoring of H5N1 HPAI virus outbreaks.     

Susceptibility of two species of wild terrestrial birds to infection with a highly pathogenic avian influenza virus of H5N1 subtype

The recent epidemic caused by H5N1 highly pathogenic avian influenza (HPAI) viruses has spread over many parts of Asia, Europe and Africa. Wild birds, particularly waterfowl, are considered to play a role in viral dissemination. However, detailed information on whether wild terrestrial birds act as carriers is currently unavailable. To investigate the susceptibility of terrestrial birds to HPAI viruses, two species of wild bird (great reed warbler and pale thrush) that are common in East Asia were infected with H5N1 HPAI virus. The results showed that both species were highly susceptible to the virus. The great reed warbler showed fatal infection with 100% mortality, but the pale thrush survived for longer periods (>8 days) with viral shedding. These findings suggest that there is variation in clinical outcome after infection of wild terrestrial birds, and that some bird species could become subclinical excretors of the H5N1 virus.     

Comparison of the replication and transmissibility of two infectious laryngotracheitis virus chicken embryo origin vaccines delivered via drinking water

Infectious laryngotracheitis (ILT) is an acute infectious viral disease that affects chickens, causing respiratory disease, loss of production and mortality in severe cases. Biosecurity measures and administration of attenuated viral vaccine strains are commonly used to prevent ILT. It is notable that most recent ILT outbreaks affecting the intensive poultry industry have been caused by vaccine-related virus strains. The purpose of this study was to characterize and compare viral replication and transmission patterns of two attenuated chicken embryo origin ILT vaccines delivered via the drinking water. Two groups of specific pathogen free chickens were each inoculated with SA-2 ILT or Serva ILT vaccine strains. Unvaccinated birds were then placed in contact with vaccinated birds at regular intervals. Tracheal swabs were collected every 4 days over a period of 60 days and examined for the presence and amount of virus using a quantitative polymerase chain reaction. A rapid increase in viral genome copy numbers was observed shortly after inoculation with SA-2 ILT virus. In contrast, a comparatively delayed virus replication was observed after vaccination with Serva ILT virus. Transmission to in-contact birds occurred soon after exposure to Serva ILT virus but only several days after exposure to SA-2 ILT virus. Results from this study demonstrate in vivo differences between ILT vaccine strains in virus replication and transmission patterns.     

Degenerative joint disease in captive waterfowl

A retrospective study was conducted to evaluate degenerative joint disease (DJD) in captive waterfowl that died or were euthanized at Fresno's Chaffee Zoo in Fresno, California, USA from 2001 to 2005. Of these, 16 out of 33 birds (48%) had DJD in one or both stifle (femoral–tibiotarsal joint; n = 13), hock (tibiotarsal–tarsometatarsal joint; n = 4), or toe joints (n = 2), based on gross, histologic and/or radiographic confirmation. No joint disease was observed in any wings, nor were any infectious pathogens isolated from affected joints. Sixteen species of waterfowl were included (n = 1 to 5 per species), with an average age at death of 12.1 years and 11.3 years for waterfowl with, and without DJD, respectively. Neither age nor sex was associated with the presence of joint disease. Waterfowl housed in the Rainforest exhibit were more likely to be diagnosed with DJD compared with waterfowl housed in the duck pond exhibit, possibly due to the rough-textured concrete surfaces in the Rainforest exhibit. Further research involving a larger number of zoological collections and birds is necessary to gain a better understanding of risk factors in captive waterfowl.     

Avian host range of Chlamydophila spp. based on isolation,antigen detection and serology

Published reports and our own diagnostic data on the avian host range of avian Chlamydophila spp. are presented in an attempt to provide evidence for the large number of bird species that have been naturally infectedwith chlamydia. The term 'chlamydia-positive' is based on either isolation of the organism and antigen detection or on serological detection of circulating antibodies. The list of chlamydia-positive birds contains the six majordomestic species (chicken, turkey, Pekin duck, Muscovy duck, goose, and pigeon), the three minor domestic species (Japanese quail, bobwhite quail, and peafowl) and a total of 460 free-living or pet bird species in 30 orders. The order Psittaciformes contains by far the most (153 of 342; 45%) chlamydia-positive bird species. More than 20% of all species per order are positive for chlamydia in the orders Lariformes (gulls, 26 of 92species; 28%), Alciformes (alks, six of 23 species; 26%), Sphenisciformes (penguins, four of 16 species; 25%), and Anseriformes (ducks and geese, 33 of 157 species; 21%). Only 5% of all bird species (14 of 259 species) inthe order Phasianiformes (gallinaceus birds) are chlamydia-positive. The different percentages of chlamydiapositive bird species reflect: (i) a high rate of investigations (e.g. of domestic birds) compared with infrequenttesting (e.g. of Charadriiformes or Cuculiformes), (ii) frequent zoonotic implications (e.g. psittacine and columbiform birds), and (iii) an assumed high susceptibility to infection and subsequent seroconversion (e.g.waterfowl).     

Experimental infection of emus (Dromaiius novaehollandiae) with avian influenza viruses of varying virulence: clinical signs, virus shedding and serology.

Two groups of emus were experimentally inoculated with a low and high pathogenic strain of avian influenza virus (AIV), type A to determine the virus susceptibility, pathogenicity, shedding and seroconversion. Emus were found susceptible to infection with AIV, with virus shedding detectable in tracheal and cloacal swabs between 3 and 10 days post-infection. Only the birds infected with the highly pathogenic viral isolate showed a brief period of mild clinical signs associated with infection. Virus recovered from the infected emus was found to be of similar pathogenicity to that of the virus inoculum. All the birds seroconverted by 10 days post-infection, as determined by haemagglutination inhibition, agar gel immunodiffusion and competitive ELISA assays. This study suggests that emus are similar to wild waterfowl in their response to AIV infection, in that they are susceptible and will replicate and shed the virus, but do not show any marked clinical signs of infection.     

Investigation of outbreaks of highly pathogenic H5N1 avian influenza in waterfowl and wild birds in Hong Kong in late 2002.

Outbreaks of highly pathogenic H5N1 avian influenza have occurred in Hong Kong in chickens and other gallinaceous poultry in 1997, 2001, twice in 2002 and 2003. High mortality rates were seen in gallinaceous birds but not in domestic or wild waterfowl or other wild birds until late 2002 when highly pathogenic H5N1 avian influenza occurred in waterfowl (geese, ducks and swans), captive Greater Flamingo (Phoenicopterus ruber) and other wild birds (Little Egret Egretta garzetta) at two waterfowl parks and from two dead wild Grey Heron (Ardea cinerea) and a Black-headed Gull (Larus ridibundus) in Hong Kong. H5N1 avian influenza virus was also isolated from a dead feral pigeon (Columba livia) and a dead tree sparrow (Passer montanus) during the second outbreak. The first waterfowl outbreak was controlled by immediate strict quarantine and depopulation 1 week before the second outbreak commenced. Control measures implemented for the second outbreak included strict isolation, culling, increased sanitation and vaccination. Outbreaks in gallinaceous birds occurred in some live poultry markets concurrently with the second waterfowl outbreak, and infection on a chicken farm was detected 1 week after the second waterfowl park outbreak was detected, on the same day the second grey heron case was detected. Subsequent virus surveillance showed the outbreaks had been contained.     

Molecular Epidemiology of Outbreak-Associated and Wild-Waterfowl-Derived Newcastle Disease Virus Strains in Finland,Including a Novel Class I Genotype

Newcastle disease (ND) is a highly contagious, severe disease of poultry caused by pathogenic strains of Newcastle disease virus (NDV; or avian paramyxovirus-1). NDV is endemic in wild birds worldwide and one of the economically most important poultry pathogens. Most of the published strains are outbreak-associated strains, while the apathogenic NDV strains that occur in wild birds, posing a constant threat to poultry with their capability to convert into more virulent forms, have remained less studied. We screened for NDV RNA in cloacal and oropharyngeal samples from wild waterfowl in Finland during the years 2006 to 2010: 39 of 715 birds were positive (prevalence, 5.5%). The partial or full-length F genes of 37 strains were sequenced for phylogenetic purposes. We also characterized viruses derived from three NDV outbreaks in Finland and discuss the relationships between these outbreak-associated and the wild-bird-associated strains. We found that all waterfowl NDV isolates were lentogenic strains of class I or class II genotype I. We also isolated a genetically distinct class I strain (teal/Finland/13111/2008) grouping phylogenetically together with only strain HIECK87191, isolated in Northern Ireland in 1987. Together they seem to form a novel class I genotype genetically differing from other known NDVs by at least 12%.     

Virus neutralizing antibodies to arboviruses in birds of the order Anseriformes in Czechoslovakia.

Sera from birds of the order Anseriformes in Czechoslovakia were examined for virus neutralizing (VN) antibodies to arboviruses. VN antibodies to Sindbis, Calovo and Tahyna viruses were found in 15, 5 and 6 out of 106 greylag goose (Anser anser) sera. Out of 38 ducks, 6 mallards (Anas platyrhynchos) and 1 garganey (Anas querquedula) contained VN antibodies to Sindbis virus, 6 mallards to Calovo virus, 4 mallards and 1 garganey to Tahyna virus, 2 mallards and 1 garganey to tick-borne encephalitis (TE) virus and 1 mallard to West Nile (WN) virus.     

Wood ducks (Aix sponsa) as potential reservoirs for avian influenza and avian paramyxoviruses

Influenza A viruses (IAVs) and avian paramyxoviruses (APMVs) are important pathogens of poultry worldwide, and both commonly occur in wild waterfowl, especially ducks in the family Anatidae. Although wood ducks (Aix sponsa) are members of the Anatidae, their behaviour differs from most other species in this family, which could affect the transmission of IAVs and APMVs. We collected cloacal and oropharyngeal swab and blood samples from more than 700 wood ducks across nine states in the eastern United States of America. No IAVs were isolated, and based on blocking enzyme-linked immunoassay ELISA results, antibodies to IAVs were only detected in 0.2% of samples. In contrast, 23 (3%) APMVs were isolated (22 Newcastle disease virus and 1 APMV-6), and antibodies to multiple serotypes of APMVs were detected in more than 60% of the samples. After-hatch-year birds were more likely to be antibody positive for APMV-4 and APMV-6 compared to hatch-year birds. Female birds were more likely to be antibody positive for APMV-4 than were male birds. Our results indicate that wood ducks are probably not an important host for IAV but are frequently infected with APMVs.     

Calamicoptes anatidus sp. nov., a new quill wall mite (Acari: Laminosioptidae) from the Greater Scaup Aythya marila (L.) (Aves: Anseriformes)

Calamicoptes anatidus sp. nov., a new species of rarely found parasitic mites of the family Laminosioptidae (Acari: Astigmata) is described from quill walls of wing covert feathers of Aythya marila Linnaeus (Anseriformes: Anatidae) captured in Poland. This is the first record of the family Laminosioptidae on birds of the order Anseriformes and the first record of this mite family in the fauna of Poland. Females of the new species are most similar to those of C. arenariae Lombert, Gaud et Lukoschus, 1984 and differ from them by the presence of the pygidial shield, which covers dorsal and ventro-lateral parts of the opisthosoma, and by having setae c2 and d2 short and subequal in length, and setae se and cp not reaching the metapodonotal shield.     

Herpesviruses of birds--a review

The family of herpesviridae is divided into the subfamilies alpha-, beta- and gammaherpesvirinae. Members of the alphaherpesvirinae (infectious laryngo-tracheitis in gallinaceous birds and duck viral enteritis in waterfowl) may cause substantial economic and ecological losses. Marek's disease and turkey herpesviruses are the only members of the gammaherpesvirinae. Most herpesviruses from free-living and pet birds are tentatively classified as bctaherpesvirinae. These may induce diseases, with variably non-specific clinical signs but including respiratory distress, ocular lesions, enteritis and liver involvement. Prominent pathological lesions consist either of haemorrhages on respiratory or intestinal epithelium or of multi-focal necrotic lesions in livers, spleen and bone marrow. At least four different plaque types of betaherpersvirinae can be differentiated in infected chick embryo fibroblasts or chick kidney cell cultures. Infectivity may be cell-associated or detectable in supernatant fluids and transformed cultured cells. All avian herpesviruses are presently grouped on the basis of results of cross neutralisation tests into 11 different serotypes.     

Effect of vaccination on transmission characteristics of highly virulent Newcastle disease virus in experimentally infected chickens

An experimental study was conducted to evaluate the effect of vaccines produced in Ethiopia from vaccine strains used worldwide on the transmission characteristics of velogenic Newcastle disease virus field strain after different vaccination schemes. Chickens were vaccinated with Hitchner B1, La Sota or I-2 via the intraocular and intranasal routes. Vaccine and challenge viruses induced high antibody levels, both in inoculated and contact birds. Prime-boost vaccination protected birds against morbidity and mortality and significantly reduced the incidence of viral shedding from chickens compared with single vaccinated and unvaccinated birds. Protection from disease and mortality was correlated with the presence of positive antibody titres (>4 log₂) at day of challenge. Most of the unvaccinated and in-contact birds excreted the virus and showed a high level of antibody titres, indicating the high infectivity of the challenge virus. The detection of the challenge virus in most of vaccinated birds demonstrated that the tested vaccination protocols cannot fully protect birds from viral infection, replication and shedding, and vaccinated–infected birds can act as a source of infection for susceptible flocks. The high mortality observed in unvaccinated birds and their contacts confirmed the virulence of the challenge virus and indicated that this field virus strain can easily spread in an unvaccinated poultry population and cause major outbreaks. Progressive vaccinations supported by biosecurity measures should therefore be implemented to control the disease and introduction of the virus to the poultry farms.     

Vaccination of chickens against H5N1 avian influenza in the face of an outbreak interrupts virus transmission.

Vaccination of chickens with a commercially available killed H5N2 vaccine was being evaluated as an additional tool to enhanced biosecurity measures and intensive surveillance for control of highly pathogenic avian influenza subtype H5N1 disease in Hong Kong in 2002. In December 2002 to January 2003, there were outbreaks of H5N1 disease in waterfowl in two recreational parks, wild water birds, several poultry markets and five chicken farms. In addition to quarantine, depopulation of the affected sheds and increased biosecurity, vaccination of the unaffected sheds and surrounding unvaccinated farms was undertaken on three farms. In at least two farms, infection spread to the recently vaccinated sheds with low rates of H5N1 mortality in sheds when the chickens were between 9 and 18 days post-vaccination. However, after 18 days post-vaccination no more deaths from H5N1 avian influenza occurred and intensive monitoring by virus culture on these farms showed no evidence of asymptomatic shedding of the virus. This provides evidence that H5 vaccine can interrupt virus transmission in a field setting.     

Antigenic variation between Newcastle disease viruses of goose and chicken origin

Newcastle disease virus (NDV) is believed to infect only domestic avian species, with waterfowl such as geese either not being infected, even by virulent strains, or developing only inapparent infection. Since the late 1990s, a new infectious disease producing high morbidity and mortality among geese broke out in many provinces of China. This disease was caused by a serotype I avian paramyxovirus known as (APMV-1)—NDV. To investigate how NDV spreads between chickens and geese, the serological similarities of NDV strains (goose-origin NDV/NA-1 and chicken-origin NDV/F48E9, F48E8) were assessed by cross-neutralization assays both in vivo and in vitro. The results indicated that antigenic variation had occurred between NDV/NA-1 strains and NDV/F48E9, F48E8 strains. Notably, NDV/NA-1 effectively protected vaccinated birds from morbidity and mortality against NDV/NA-1 strain challenge and significantly reduced virus shedding from the vaccinated birds when compared with F48E9-vaccinated birds. This might provide clues to the evolution of the goose NDV.     

The genome of budgerigar fledgling disease virus, an avian polyomavirus

Budgerigar fledgling disease virus (BFDV) represents the first avian member of the Polyomavirus family. In contrast to mammalian polyomaviruses BFDV exhibits unique biological properties, in particular it is able to cause an acute disease with distinct organ manifestations in affected birds. Here we present the complete nucleotide sequence of the BFDV genome, consisting of 4980 bp. When compared to published nucleotide sequences of other polyomaviruses, the BFDV genome exposes a number of very similar structural features, and undoubtedly qualifies as a member of that family of viruses. The most important differences include a large T antigen remarkably reduced in size, and an origin of replication region with fundamental deviations from the origin structure of all other polyomaviruses. The specific characteristics of the BFDV genome may be used to place this virus into a distinct subgroup within the Polyomavirus family and may give a clue to the elucidation of its extraordinary biological properties.