Showing papers in "Avian Pathology in 1999"
TL;DR: The regime of administering the infectious bronchitis Ma5 vaccine (Massachusetts serotype) at 1 day old and the heterologous 4/91 vaccine at 2 weeks of age, was shown to be highly effective in protecting the respiratory tract of specified pathogen free chickens.
Abstract: The regime of administering the infectious bronchitis (IB) Ma5 vaccine (Massachusetts serotype) at 1 day old and the heterologous 4/91 vaccine at 2 weeks of age, was shown to be highly effective in protecting the respiratory tract of specified pathogen free chickens. Protection, as measured by assessing ciliary activity of the tracheal epithelium following challenge, was excellent against challenge at 5 weeks of age with IB strains of many serotypes, isolated from disease outbreaks in different parts of the world. This vaccination protocol was more effective than revaccination with a vaccine of the same serotype as the first vaccine. Furthermore, significantly better protection was seen when the Ma5 vaccine was given before, rather than at the same time as or following, the 4/91 vaccine. It is suggested that the use of these two IB vaccines will frequently broaden the protection possible against challenge with IB isolates of many different serotypes, without the need to develop a new IB vaccine to combat ...
230 citations
TL;DR: It is shown that vaccinal IBV can be detected for several weeks, and the dominance of the IBV 793/B type and Avian pneumovirus (APV) vaccines, applied at the hatchery or later, were either not detected or were detected only after a delay of 1 to 3 weeks.
Abstract: In longitudinal studies, 13 flocks were swabbed twice each week for the life of the flock (up to 46 days). The swabs were analyzed by type-specific reverse transcriptase polymerase chain reactions. Massachusetts type vaccinal infectious bronchitis virus (IBVs), applied at the hatchery, were usually maximal during the first week, as expected and, notably, remained detectable for 3 to 4 weeks, occasionally longer. IBV of the 793/B type (also known as 4/91 and CR88) was detected in 11/13 flocks (85%). The time of first detection of 793/B varied over several weeks and was sometimes within the first week in low amounts, which increased gradually. In some flocks, detection of 793/B remained intermittent. IBV types D274 and D1466 were each detected once, in the same flock, for short periods, in low amounts, and in the presence of higher amounts of 793/B. In swabs from a further 30 broiler flocks, plus those already mentioned, there was an incidence for 793/B, D274 and D1466 of 79, 10 and 2%, respectively. Avian ...
199 citations
TL;DR: Although O. rhinotracheale is difficult to identify, some commercial identification systems have been found to be suitable, although the media used in such systems will not always support its growth.
Abstract: Ornithobacterium rhinotracheale is a relatively recently discovered bacterium of the rRNA superfamily V It is of worldwide distribution in commercial poultry, in which it is associated with respiratory diseases, and it is also found in wild birds Airsacculitis and pneumonia are the most common features of infection with O rhinotracheale These signs can be induced by aerosol in intra-tracheal or intra-thoracic administration of the organism, and can be aggravated by other factors, such as respiratory viruses, bacteria or climatic conditions Osteitis, meningitis and joint-infections, which can be induced by intravenous application, have been associated with O rhinotracheale, but it remains uncertain whether the organism should be regarded as a primary pathogen The infection can be transmitted horizontally by aerosol, as well as vertically through eggs, which probably accounts for its rapid and worldwide spread Although O rhinotracheale is difficult to identify, some commercial identification systems have been found to be suitable, although the media used in such systems will not always support its growth A PCR assay was also found to be suitable for identification purposes Twelve serotypes can be distinguished within the species O rhinotracheale, of which serotype A is the most prevalent Genetic investigation has revealed that more species or subspecies probably exist within the genus Ornithobacterium Therapeutic treatment of the disease can be difficult because acquired resistance against the regular antibiotics is very common within the genus Vaccination with autogenous inactivated vaccines has been successful in reducing clinical signs, but success depends on the adjuvant used Only potent oil adjuvants are effective in young birds with maternal antibodies, but the use of these adjuvants is known to induce some local reactions Live vaccination is feasible, but up to now, no avirulent strains of O rhinotracheale have been found Vaccination of broiler breeders induced protection against experimental infection of the progeny to at least 3 weeks of age
187 citations
TL;DR: Of the approximately 9000 bird species, about 232 species in 23 orders have been reported to have acquired a natural poxvirus infection, and it is likely that many more birds are susceptible to avipoxviruses.
Abstract: A review is given of the occurrence of poxviruses in different bird species. The first publications appeared in Europe around 1850. At that time, pox as a definite disease entity was diagnosed on the basis of clinical signs, while later the detection of Bollinger's inclusion bodies (1877) allowed an aetiological diagnosis by microscopically visible viral aggregates. Virus isolation in embryonated chicken eggs and direct electron microscopy gained importance as diagnostic tools in the 1950s. Also briefly described are avipoxvirus taxonomy, virus characteristics, clinical signs, modes of prevention and diagnostic procedures. Of the approximately 9000 bird species, about 232 species in 23 orders have been reported to have acquired a natural poxvirus infection. However, it is likely that many more birds are susceptible to avipoxviruses.
183 citations
TL;DR: It is demonstrated that chickens vaccinated with inactivated H5 whole virus AI vaccines were protected from clinical signs and death, but usage of vaccine generally did not prevent infection by the challenge virus, as indicated by recovery of virus from the oropharynx.
Abstract: The influence of vaccine strain and antigen mass on the ability of inactivated avian influenza (AI) viruses to protect chicks from a lethal, highly pathogenic (HP) AI virus challenge was studied. Groups of 4-week-old chickens were immunized with inactivated vaccines containing one of 10 haemagglutinin subtype H5 AI viruses, one heterologous H7 AI virus or normal allantoic fluid (sham), and challenged 3 weeks later by intra-nasal inoculation with a HP H5 chicken-origin AI virus. All 10 H5 vaccines provided good protection from clinical signs and death, and produced positive serological reactions on agar gel immunodiffusion and haemagglutination inhibition tests. In experiment 1, challenge virus was recovered from the oropharynx of 80% of chickens in the H5 vaccine group. In five H5 vaccine groups, challenge virus was not recovered from the cloaca of chickens. In the other five H5 vaccine groups, the number of chickens with detection of challenge virus from the cloaca was lower than in the sham group (P < 0.05). Reductions in the quantity of challenge virus shed from the cloaca and oropharynx were also evident in some H5 vaccinate groups when compared to the sham group. However, there was no positive correlation between the sequence identity of the haemagglutinin gene from the vaccine strain and challenge virus, and the ability to reduce the quantity of challenge virus shed from the cloaca or oropharynx. As the quantity of AI antigen in the vaccines increased, all parameters of protection improved and were virus strain dependent. A/turkey/Wisconsin/68 (H5N9) was the best vaccine candidate of the H5 strains tested (PD50= 0.006 μg AI antigen). These data demonstrate that chickens vaccinated with inactivated H5 whole virus AI vaccines were protected from clinical signs and death, but usage of vaccine generally did not prevent infection by the challenge virus, as indicated by recovery of virus from the oropharynx. Vaccine use reduced cloacal detection rates, and quantity of virus shed from the cloaca and oropharynx in some vaccine groups, which would potentially reduce environmental contamination and disease transmission in the field.
133 citations
TL;DR: The antigenic and genetic relationships between very virulent infectious bursal disease viruses from different countries were investigated and all viruses exhibited antigenic profiles characterized by no binding of Mabs 3 and 4, which might thus be helpful for differentiating classical and vvIBDVs.
Abstract: The antigenic and genetic relationships between very virulent (vv) infectious bursal disease viruses (IBDV) from different countries were investigated. Antigenic characterization was performed using an antigencapture ELISA based on a panel of seven neutralizing monoclonal antibodies (Mabs), which probe at least three VP2-located antigenic domains. All these domains are reactive in the Faragher 52/70 (F52/70) reference strain for European classical serotype 1 IBDV. Genomic characterization was achieved by reverse transcription, amplification and direct sequencing of a genome fragment encoding the VP2 variable domain. Eleven vv isolates from France were compared to the British, Dutch and Belgian UK661, DV86 and 849VB viruses, and to an early vv isolate obtained from the Ivory Coast in 1988. All viruses exhibited antigenic profiles characterized by no binding of Mabs 3 and 4. Lack of binding of Mabs 3 and 4 might thus be helpful for differentiating classical and vvIBDVs. None of the non-French strains resemb...
116 citations
TL;DR: The final description of the ascites aetiology may lie in the concept of a circuit of events between the cardiac, pulmonary and vascular systems that satisfy the metabolic requirements of the bird.
Abstract: In recent years, ascites research has centred on gaining an increased understanding of pulmonary hypertension syndrome together with the potential role of primary cardiac pathologies. The impact at a cellular level of factors which trigger ascites and substances that protect against it has also been documented. Primary pulmonary hypertension has been induced when birds are exposed to hypoxia during incubation. The conditions experienced during this phase of development may impact on the ability of the bird to regulate its basal metabolic rate through endocrine signals controlled by thyroid activity. The extent of ventilation in the lung influences the ability of the bird to oxygenate haemoglobin. Ventilation/ perfusion mismatches may occur prior to or post-hatching. This factor has been studied extensively using the pulmonary artery/bronchus clamp model. At high altitude, a decreased ventilation/perfusion ratio may occur following the effective increase in physiological dead space due to the lowered oxygen tension at the level of the parabronchi. This explains the mechanism by which ascites is triggered by hypoxia in this particular situation. The effects of ascites are ameliorated by the use of beta agonists and dietary arginine, which act by increasing ventilation and blood flow in the lungs and thus correcting a ventilation/perfusion mismatch. Transient bacterial and viral infections may also influence the induction of pulmonary hypertension. The increases in blood viscosity associated with ascites are most probably a consequence of the condition rather than a cause. A bird may alleviate the effects of pulmonary hypertension by decreasing blood viscosity through inhibition of platelet function, increased erythrocyte deformability and the production of coronary relaxants. Evidence is accumulating that primary cardiac pathology may be associated with a number of ascites cases. Broilers that subsequently develop ascites, exhibit lower heart rates than their normal flock mates. Furthermore, during ascites, hypoxic broilers exhibit bradycardia as opposed to the expected tachycardia. In these cases, a tachycardia induced by feed restriction may protect the bird by raising its cardiac output. Right atrio-ventricular regurgitant flow velocities in chickens are relatively slow compared with similar regurgitant flows induced by pulmonary hypertension in other species. The conduction system in the avian heart is specialized and contains a recurrent bundle branch that innervates the right atrio-ventricular valve, thus initiating active valve closure before right ventricular systole. This predisposes the heart to right ventricular volume overload through a valvular incompetance following a failure of valvular innervation. The resultant elevated diastolic wall stress can trigger the production of angiotensin II and its converting enzyme, which mediate ventricular hypertrophy. Subclinical myocardial damage, irrespective of its cause, can be detected by the presence of troponin T in the blood. Reactive oxygen species may damage cell membranes compromising cellular function in a number of body systems. A positive correlation exists between oxidized glutathione concentrations and right ventricular weight ratio. This indicates a failure to cope with oxidative stress at the level of the respiratory membrane. It is not known if it is possible to modulate levels of antioxidants at this location and hence protect the bird. The final description of the ascites aetiology may lie in the concept of a circuit of events between the cardiac, pulmonary and vascular systems that satisfy the metabolic requirements of the bird. A deficit in one of these systems, at a level that prevents adequate compensation from other components, triggers the pathological cascade that results in the end point of clinical ascites.
108 citations
TL;DR: Eighteen isolates of infectious bronchitis virus from Italy and Poland in 1997 to 1998 were comprehensively analysed by serum haemagglutination inhibition and virus neutralization tests, and by type-specific polymerase chain reactions and spike protein S1 gene sequencing, showing four types of IBV co-existing within a single year.
Abstract: Eighteen isolates of infectious bronchitis virus (IBV) from Italy and Poland in 1997 to 1998 were comprehensively analysed by serum haemagglutination inhibition and virus neutralization tests, and by type-specific polymerase chain reactions and spike protein S1 gene sequencing. Four types of IBV (793/B, 624/I, B1648 and Massachusetts) were detected in Italy, while the presence of 793/B was confirmed in Poland. This showed that not only were four types of IBV co-existing within a single year, but also that several types of IBV have persisted in Europe for many years (at least 13 to 14 years for types B1648 and 793/B). Sequencing of the S1 gene of the 624/I isolate confirmed this as a unique type of IBV.
106 citations
TL;DR: Results indicate that Colorado should be classified as an APV, but the antigenic differences suggest that it does not belong to subgroups A or B, and represents a separate subgroup (subgroup C) or possibly a separate serotype.
Abstract: An avian pneumovirus (APV) isolated from turkeys showing respiratory disease in Colorado, USA, shared some characteristics with earlier subgroup A and B APV strains. This virus, designated the Colorado isolate (Colorado), when used after either seven passages in chick embryo fibroblasts (CEF), or seven passages in CEF followed by six turkey passages, induced clinical signs in turkeys that were similar to those caused by earlier APV strains. Although it induced an antibody response in specific pathogen free chickens, clinical signs were not seen. Unlike subgroups A or B, Colorado did not cause ciliostasis in tracheal organ cultures, but produced a cytopathic effect in chick embryo fibroblasts typical of that seen with other APV strains. Monospecific antisera to A or B strains did not neutralize Colorado and vice versa; nor did monoclonal antibodies, which neutralize subgroup A or B strains, neutralize Colorado. However, it was partially neutralized by a subgroup A hyperimmune serum. A homologous enzyme-linked immunosorbent assay (ELISA) antigen was essential for the detection of Colorado antibodies, since ELISAs in which subgroup A or B strains were used detected antibody to Colorado very poorly. Subgroup A and B vaccines protected turkeys against challenge with Colorado. However, while Colorado protected turkeys, and to some extent chickens, against subgroup A strains, protection against a subgroup B challenge was less good in both species. These results indicate that Colorado should be classified as an APV, but the antigenic differences suggest that it does not belong to subgroups A or B, and represents a separate subgroup (subgroup C) or possibly a separate serotype.
94 citations
TL;DR: A complete set of ITS1-based, species-specific primers for the detection and discrimination of all seven Eimeria species that infect the domestic fowl is now available.
Abstract: A polymerase chain reaction (PCR) assay, based on the amplification of internal transcribed spacer 1 (ITS1) regions of ribosomal DNA, was developed for the chicken coccidian species Eimeria maxima, E. mitis and E. praecox. Thus, taking into account our previous work, a complete set of ITS1-based, species-specific primers for the detection and discrimination of all seven Eimeria species that infect the domestic fowl is now available. ITS1 primers for each of these seven species of Eimeria were also used as capture probes in a paper chromatography assay (PACHA). The addition of PACHA to the PCR assay provided a faster, more simplified read-out compared to staining of amplified bands in an agarose gel with ethidium bromide.
91 citations
TL;DR: Studies in floor pens and the field indicate that broilers given various drug programs can develop immunity when exposed to natural infections but that this process takes time: solid immunity not developing until birds are 6 to 7 weeks of age, which suggests that drugs should not be withdrawn from the feed prematurely since birds may not have had time to develop adequate immunity.
Abstract: The long-held view that anticoccidial drugs, to a greater or lesser extent, interfere with the development of immunity to Eimeria species may no longer be correct because few drugs, if any, are capable of preventing some degree of parasite multiplication. Acquisition of immunity is, therefore, a real possibility, providing sufficient parasites are present in the environment. Immunity is an important consideration during the rearing of replacement layers, broiler breeders, turkeys, and gamebirds, but little research has been carried out on the effects of drugs on immunity development in these categories of stock. In recent years, there has been a change in the perception of the significance of immunity in broilers, and some broiler producers have taken this into consideration when designing drug programs for use in the field. Studies in floor pens and the field indicate that broilers given various drug programs can develop immunity when exposed to natural infections but that this process takes time: solid immunity not developing until birds are 6 to 7 weeks of age. This suggests that drugs should not be withdrawn from the feed prematurely since birds may not have had time to develop adequate immunity.
TL;DR: It could be shown that all adenoviruses isolated from various field cases of infectious hydropericardium (Angara Disease) in several countries belong to fowlAdenovirus serotype 4.
Abstract: Serology, restriction enzyme analysis and polymerase chain reactions were used to classify a total of 12 fowl adenoviruses (FAV) isolated from clinical cases of infectious hydropericardium from fie...
TL;DR: It is indicated that infections with intestinal spirochaetes are a common but currently under-diagnosed cause of wet litter and/or reduced egg production in broiler breeder and layer flocks in Australia.
Abstract: Faecal samples (n = 1786) from chickens in broiler breeder (n = 28), layer (n = 22) or broiler (n = 19) flocks in the eastern states of Australia were cultured for intestinal spirochaetes. Overall, birds in 42.9% of broiler breeder and 68.2% of layer flocks were colonized with spirochaetes, but no birds in broiler flocks were infected. Colonization rates in infected flocks ranged from 10 to 100% of birds sampled. Faeces from colonized flocks were on average 14% wetter than those from non-colonized flocks. There was a highly significant association between colonization with spirochaetes and the occurrence of wet litter and/or reduced production. A subset of 57 spirochaete isolates from birds in 16 flocks were identified to the species level using a panel of polymerase chain reaction tests. Isolates from nine (56%) of these flocks were spirochaetes that are known to be pathogens of poultry: Serpulina pilosicoli was isolated from birds from five flocks, birds from two flocks were infected with Serpulina intermedia, and in two other flocks both species were identified. Isolates from the other seven flocks belonged to other Serpulina species, which are currently of unknown pathogenicity. This study indicates that infections with intestinal spirochaetes are a common but currently under-diagnosed cause of wet litter and/or reduced egg production in broiler breeder and layer flocks in Australia.
TL;DR: 149 virus isolates were identified as pigeon variant PMV-1 (PPMV- 1).
Abstract: In Germany all avian paramyxoviruses (APMV) isolated in regional laboratories are collected and characterized by the National Reference Laboratory. From 1992 until 1996, 635 APMV-1 virus isolates were submitted from almost all regions. Of these viruses, 371 were isolated from chickens, 39 from other poultry, 171 from pigeons and 54 from exotic birds. All isolates were examined for virulence in intracerebral pathogenicity index (ICPI) tests, for their ability to react with a panel of monoclonal antibodies (mAb) and their thermostability. In addition, the nucleotide sequences of the cleavage site of the fusion protein of a few virus isolates were determined. Most isolates from chickens and other poultry were of the velogenic pathotype. This virus was responsible for the epizootic in 1993 to 1995 in many small flocks. The same virus was obtained from some pigeons and some exotic birds. The pathogenicity of the velogenic/epizootic virus was high with most viruses giving ICPI values of 1.8 to 1.9, and the sequences of the cleavage site of all velogenic isolates tested were closely related. However, viruses isolated at the beginning of the epizootic period differed from viruses isolated towards the end in their reaction with some mAbs. 149 virus isolates were identified as pigeon variant PMV-1 (PPMV-1). Most of these were obtained from pigeons but a few were isolated from chickens and other birds. Most lentogenic isolates proved to be vaccine virus strains.
TL;DR: A total of 100 free-living urban pigeons (Columba livia) were captured in the city of Santiago, Chile, in order to evaluate, for the first time, their health status, and seven species of nematodes were identified.
Abstract: A total of 100 free-living urban pigeons (Columba livia) were captured in the city of Santiago, Chile, in order to evaluate, for the first time, their health status. Negligible antibody titres (1 to 3 log2) were detected in 22% of the birds against a strain of the paramyxovirus (PMV) serotype 1. No pigeons had antibodies against PMV serotype 7 and avian influenza. Salmonella sp. belonging to serogroups B and D were isolated from the intestinal tract of three pigeons (3%). The protozoa Haemoproteus columbae, Plasmodium sp., and Leucocytozoon sp. were not detected in any pigeons. Trichomonas gallinae was detected in 11%, without observation of either clinical signs or gross pathological changes at necropsy. Sixty-seven percent of the birds showed the presence of the chewing lice Columbicola columbae and Campanulotes bidentatus compar, and 1% harboured the mite Laminosioptes cysticola. Seven species of nematodes were identified. The frequency at which each species was detected was; Tetrameres sp. (14%), Capi...
TL;DR: In a study from October, 1996 to March, 1997, 34 pigeons in three different locations were studied for parasites, revealing that Pseudolynchia canariensis (the 'pigeon fly') was the most prevalent parasite (100%).
Abstract: In a study from October, 1996 to March, 1997, 34 pigeons in three different locations were studied for parasites. The majority of birds in Nakulabye appeared clinically sick, while those within Makerere University and Wandegeya were apparently healthy. Biometric data were taken for each bird and, during the process, ectoparasites were collected. Faecal and blood samples were obtained. The study of ectoparasites revealed that Pseudolynchia canariensis (the 'pigeon fly') was the most prevalent parasite (100%). The louse Columbicola columbae was next in prevalence (94.1%). It is postulated that the pigeon fly transports this parasite. Three lice of economic importance were found: Menopon gallinae, Menacanthus stramineus and Chelopistes meleagridis. Cestodes were the only helminths found, occurring in 23.5% of the birds. Identification of the cestodes was not possible. Haemoparasites were mainly of two genera, Haemoproteus and Plasmodium. Haemaproteus was the most prevalent (76.5%). This was possibly due to t...
TL;DR: In the described flock of geese, a virus-induced immunosuppression could have been a predisposing factor for other infectious agents such as Riemerella anatipestifer or Aspergillus fumigatus, thus contributing to the increased losses and developmental disorders.
Abstract: Diagnostic investigations in a large commercial flock of geese with a history of increased losses and runting, lead to the negative contrast electron microscopic detection of circovirus-like viruses in the lymphoreticular tissue in eight of nine selected geese with growth retardation. With the exception of a mild cloudiness of some air sacs, macroscopic changes pointing to an infection were missed. Histopathological changes concentrated on the lymphoreticular tissue. Lymphocytic depletion and histiocytosis were most evident in the bursa of Fabricius. Basophilic globular inclusions were found in the cytoplasm of medullar and cortical bursal follicular cells, and bursal epithelial cells. Ultrastructural examination of these inclusions revealed paracrystalline or multilayered arrays, or randomly arranged complexes of isometric viral particles, about 14 nm in diameter. The pathological appearence of this, so far unknown, infection in geese shows numerous similarities to circovirus infection in pigeons. In the described flock of geese, a virus-induced immunosuppression could have been a predisposing factor for other infectious agents such as Riemerella anatipestifer or Aspergillus fumigatus, thus contributing to the increased losses and developmental disorders.
TL;DR: Although it was not possible to trace the origin of infection, the epidemiological investigation revealed connections between several outbreaks and emphasized the well-known risk factors for avian influenza such as bird movement, rearing of mixed populations and contact with migratory waterfowl.
Abstract: Between the month of October 1997 and January 1998, eight outbreaks of highly pathogenic avian influenza were diagnosed in the Veneto and Friuli-Venezia Giulia regions in north-eastern Italy. For each of the eight outbreaks, influenza A virus of subtype H5N2 was isolated and the inoculation of susceptible chickens confirmed these viruses to be extremely virulent with intravenous pathogenicity indices in 6-week-old chickens of 2.98 to 3.00. Although it was not possible to trace the origin of infection, the epidemiological investigation revealed connections between several outbreaks and emphasized the well-known risk factors for avian influenza such as bird movement, rearing of mixed populations and contact with migratory waterfowl. Control measures listed in European Union directive 92/40/EEC were implemented promptly and spread of the infection to intensively-reared domestic poultry was avoided.
TL;DR: Results suggest that a selection for increased resistance to SE may be efficient, and the heritability of resistance of poultry to Salmonella enteritidis was investigated, which appeared to be heritable.
Abstract: The heritability of resistance of poultry to Salmonella enteritidis (SE) was investigated. Three measurements of resistance were made: survival after intramuscular inoculation of 419 day-old chicks, absence versus presence of Salmonella in spleens and caeca 4 weeks after oral inoculation of 304 hens at peak of laying, and antibody response of 228 hens following two inoculations of an aroA mutant of this serotype. In the first two models of infection, resistance appeared to be heritable. The heritability was estimated from the sire and dam components, respectively, at 0.14 ± 0.10 and 0.62 ± 0.16 for chick mortality, 0.47 ± 0.21 and 0.13 ± 0.26 for resistance to spleen contamination, and 0.24 ± 0.15 and 0.53 ± 0.26 for resistance to caecal contamination in laying hens. By contrast the estimated heritability of antibody response was very low (0.03 ± 0.08 and 0.10 ± 0.08 when estimated from the sire and dam components, respectively). These results suggest that a selection for increased resistance to SE may be...
TL;DR: Low cardiac index in broiler chickens appears to be the key haemodynamic problem leading to hypoxaemia and ultimately cardiovascular failure in fast growing broilers.
Abstract: The present study examines the differences in blood gas parameters, cardiac output, cardiac index, oxygen delivery and tissue oxygen extraction in slow growing chickens (leghorn and feed restricted...
TL;DR: Serpulina intermedia strain HB60, isolated from an Australian hen with diarrhoea, was used to infect 10 individually caged 14-week-old laying hens, and wet faeces in layer and broiler breeder flocks were recorded.
Abstract: Serpulina intermedia strain HB60, isolated from an Australian hen with diarrhoea, was used to infect 10 individually caged 14-week-old laying hens Another 10 birds were sham inoculated with sterile broth Birds were kept for 16 weeks, and faecal water content, egg production and body weights recorded Strain HB60 was isolated from the faeces of nine of the infected birds at irregular intervals throughout the experiment, and from their caeca at slaughter Infected birds tended to be lighter and their faeces, on average, were significantly wetter (by 285%; P < 0002) than those of the controls Significant reductions in mean number of eggs laid (14/week; P < 0002) and mean egg weights (116 g; P < 005) were recorded in infected birds Colonization did not induce any characteristic pathological changes S intermedia is potentially an economically significant cause of reduced egg production, and wet faeces in layer and broiler breeder flocks
TL;DR: It is suggested that buying eggs or poultry abroad and exchanging poultry within the country were factors, more important than wild birds, to explain the higher NDV seropositivity in pure-bred poultry flocks.
Abstract: Blood samples and cloacal swabs from poultry were collected in 107 small chicken flocks and 62 pure-bred poultry flocks to determine their status regarding Newcastle disease virus (NDV) infection. A questionnaire emphasizing potential contacts of poultry with wild birds and management practices associated with NDV infection was completed for each flock. Additionally, 1576 wild bird carcasses of 115 different bird species were collected from hunters and taxidermists. Poultry sera and tissue fluids of wild birds were tested for NDV antibodies using a blocking ELISA. Cloacal swabs were subjected to reverse transcription polymerase chain reaction (RT-PCR) for NDV genome detection. In-herd NDV seroprevalences between 5 and 29% were found in one small chicken flock, as well as in four pure-bred poultry flocks. NDV antibody positive wild birds were found in 10.2% of all wild birds examined. Highest proportions (i.e. 15%) of positive birds per species were found among sparrowhawks, kites, tawny owls, eagle owls, ...
TL;DR: It is hypothesised that inoculation withCAV and IBDV at day 21 enhanced the development of bacterial chondronecrosis in birds exposed to S. aureus and inoculated with CAV andIBDV.
Abstract: A series of experiments was designed in an attempt to reproduce bacterial chondronecrosis with osteomyelitis in broiler chickens using a natural route of infection. Birds in isolators were exposed to a suspension of Staphylococcus aureus by aerosol or exposed to S. aureus and subsequently inoculated with chicken anaemia virus (CAV) alone, or with CAV and infectious bursal disease virus (IBDV). Subsequently, S. aureus was recovered and bacterial chondronecrosis with osteomyelitis was diagnosed, by histology, in the proximal end of the femur and/or tibiotarsus of lame birds exposed to S. aureus with and without CAV and IBDV infections. Birds fed 60% of the recommended feed intake for the breed developed a lower incidence of S. aureus infection and/or bacterial chondronecrosis (P < 0.05) than birds fed 100% of the recommended intake. A significantly lower incidence of S. aureus was recovered (P < 0.05) in birds simultaneously exposed to S. aureus and inoculated with CAV and IBDV at day 21, than in birds exposed to S. aureus at day 10, and inoculated with CAV and IBDV at day 21. With the exception of birds exposed to S. aureus at 1 day old, a higher incidence of bacterial chondronecrosis was diagnosed in birds exposed to S. aureus and inoculated with CAV and IBDV than in birds exposed to S. aureus alone. It is hypothesised that inoculation with CAV and IBDV at day 21 enhanced the development of bacterial chondronecrosis in birds exposed to S. aureus at day 10 and fed 100% of the recommended feed intake or ad libitum.
TL;DR: It is concluded that the direct detection of IBV in tracheal tissues by RT-PCR is more sensitive than IHC and that the RT- PCR technique is able to distinguish between types ofIBV.
Abstract: Oligonucleotide pairs were constructed for priming the amplification of fragments of nucleocapsid (N) protein and spike glycoprotein (S) genes of avian infectious bronchitis virus (IBV) by reverse transcriptionpolymerase chain reaction (RT-PCR). One oligonucleotide pair amplified a common segment of the N-gene and could detect various strains of IBV in allantoic fluid from inoculated chicken embryos, and in tracheal tissue preparations from experimentally infected chickens. Four pairs of oligonucleotides selectively primed the amplification of the S1 gene of Massachusetts/Connecticut, D1466, D274/D3896 and 793B strains of IBV, respectively. Groups of specific pathogen free chickens were experimentally inoculated with the Massachusetts (H120, M41), the D1466 and the 793B strains of IBV, and tracheal tissue preparations were made from each bird for RT-PCR and for immunohistochemistry (IHC) up to 3 days post-inoculation. The N-gene RT-PCR detected IBV in 82% of the chickens, while IHC only detected IBV in 60%. This difference was significant (P<0.02). The detection rate by N-gene RT-PCR varied from 67 to 100% for the various strains of IBV inoculated. The S1 gene oligonucleotide pairs were applied to the same tissue preparations and they detected specifically the Massachusetts (M41 and H120), the D1466 and the 793B strains of IBV at rates varying between 58 and 92%. When the mixtures of the primers were applied, the detection rate in tissue preparations was reduced to the level of 50 to 67%. It is concluded that the direct detection of IBV in tracheal tissues by RT-PCR is more sensitive than IHC and that the RT-PCR technique is able to distinguish between types of IBV.
TL;DR: Infection with O. rhinotracheale appears to be restricted to the respiratory tract, with lesions only evident in birds previously infected with NDV, even though a strong serological response can be established in the absence of prior viral infection.
Abstract: Immunohistochemical techniques were used to prove that Ornithobacterium rhinotracheale was the causative agent of lesions in the air sacs and lungs in chickens, but only after infection with Newcastle Disease virus (NDV). At first, the bacteria attached to the epithelium of the air sacs. Subsequently, they infiltrated the air sacs, and caused thickening of the air sacs, the formation of oedematous and granulomatous tissue, and accumulation of macrophages. The infection peaked at 5 to 9 days, after which recovery was seen. In the lungs, some areas with bronchially-associated lymphoid tissue were affected. The other organs investigated were shown not to be affected. In the absence of NDV infection, aerosol exposure of chickens to O. rhinotracheale only resulted in minimal and temporary microscopic air sac lesions. No O. rhinotracheale cells or fragments could be detected at any time point later than 2 days post-exposure. In spite of the absence of visible lesions, chickens exposed to O. rhinotracheale without prior NDV infection reacted serologically. The duration and the titre of this immune response was indistinguishable from that obtained in chickens exposed after NDV infection. Thus, infection with O. rhinotracheale appears to be restricted to the respiratory tract, with lesions only evident in birds previously infected with NDV, even though a strong serological response can be established in the absence of prior viral infection.
TL;DR: A juvenile black-backed gull from the Manawatu region of New Zealand was found to have chronic airsacculitis due to Aspergillus spp, which suggests that circoviruses may be more widespread in avian species than previously recognized and may be responsible for diseases associated with immunosuppression in free-living birds.
Abstract: A juvenile black-backed gull (Larus dominicanus) from the Manawatu region of New Zealand was found to have chronic airsacculitis due to Aspergillus spp. Histologically, there was moderately severe inflammation in the bursa of Fabricius associated with large, basophilic, intracytoplasmic inclusions, which ultrastructurally had an appearance typical of circovirus inclusions. This finding suggests that circoviruses may be more widespread in avian species than previously recognized and may be responsible for diseases associated with immunosuppression in free-living birds.
TL;DR: It is concluded that in line 72, replication and spread of MDV is more efficient and T cell responses in early infection are greater, favouring the tumour stage of the disease.
Abstract: Changes in lymphocyte distribution in spleens of Marek's disease virus (MDV) infected White Leghorn chickens of line 72 (MD susceptible) and line 61 (MD resistant) were studied by immunocytochemistry. Lymphocytes expressing the MDV antigen pp38 (predominantly B cells) were detected from 4 to 6 days post-inoculation (d.p.i.) but not at or after 8 d.p.i., and were more numerous in line 72. In line 61, infection resulted in depletion of B lymphocytes and an increase in T lymphocytes from 3 to 6 d.p.i., but no change in distribution of these cells. From 8 d.p.i., the B-dependent tissue began to recover and the T cells decreased in number. In line 72, infection caused a dramatic change in lymphocyte distribution, with formation of 'lymphoid lesions'. Diffuse, irregular patches of B lymphocytes, around the capillaries, became surrounded by large aggregates of TCRαβ1+ CD8+ and CD4+ lymphocytes, bordered by a band of TCRγδ+ lymphocytes. From 8 d.p.i., the B-dependent areas partially recovered, while TCRαβ1+ CD4+ ...
TL;DR: Birds reared in commercial houses and given a synthetic drug followed by ionophores, also developed immunity to Eimeria species, and Immunity was acquired more rapidly to E. maxima than E. acervulina or E. tenella.
Abstract: The acquisition of immunity to Eimeria species was studied in broilers reared in floor-pens on new and used litter, and given different anticoccidial drug programmes. Programmes included a single drug (synthetic compound or ionophore) given in the starter and grower feed, or 'shuttle' programmes comprising a synthetic drug followed by an ionophore (or vice versa) given in the starter and grower feeds, respectively. None of the drug programmes prevented parasite multiplication, since oocysts were found in the intestines of birds and in the litter. Birds were challenged at weekly intervals with a mixture of species (E. acervulina, E. maxima and E. tenella) in order to establish whether protective immunity had developed. Birds reared on used litter that received no medication acquired immunity by 5 weeks, whereas birds reared on new litter were not fully protected against a challenge inoculum until 7 weeks of age. Apart from birds given an ionophore followed by a synthetic drug, medicated birds developed imm...
TL;DR: Vaccination did not prevent infection and excretion of either challenge virus, however, when compared with unvaccinated birds, vaccination reduced significantly the length of time virus was excreted and the overall proportion of swabs that were positive.
Abstract: The Newcastle disease virus isolated from healthy turkeys in outbreak GB 97/6 was used to challenge 4-week-old turkeys and chickens, which were either not vaccinated or had received a single dose o...
TL;DR: Findings indicate that thrombocytes may play a role in innate immunity to bacteria in the chicken.
Abstract: The potential role of chicken thrombocytes in immune responses to Salmonella, Escherichia coli and other bacteria was investigated by in vitro assays of phagocytosis and respiratory burst activity. Thrombocytes were found to phagocytose bacteria, but were found to be less phagocytic than heterophils. Oxidative burst activity was generated upon challenge of thrombocytes with various Salmonella strains, E. coli, three other bacterial species, and zymosan A. These findings indicate that thrombocytes may play a role in innate immunity to bacteria in the chicken.