Showing papers in "Avian Pathology in 1997"
TL;DR: Since there are no methods at present to prevent resistance, more attention should be given to developing strategies for preserving the efficacy of anticoccidial drugs.
Abstract: Anticoccidial drugs are widely used for the control of coccidiosis in the fowl which has inevitably led to the development of drug resistance. Resistance has developed to all of the compounds that have been introduced and if chemotherapy is to remain the principal method of control of coccidiosis, it will be important to continue the search for new anticoccidial agents. Knowledge of biochemical pathways present in the Eimeria parasite and how they differ from those of the host might help identify novel targets for inhibition. Studies of the mode of action of drugs are required if the biochemical mechanisms of resistance are to be understood. Information on the genetic origins of resistance, the stability of resistance and the factors involved in the spread of resistance throughout parasite populations is required. Since there are no methods at present to prevent resistance, more attention should be given to developing strategies for preserving the efficacy of anticoccidial drugs.
292 citations
TL;DR: The humoral, local and cellular responses of the chicken to IBV are reviewed, together with genetic resistance of theChicken, and changes in the S1 protein may be related to differences in tissue tropisms shown by different strains.
Abstract: Summary The immunopathogenesis of infectious bronchitis virus (IBV) infection in the chicken is reviewed. While infectious bronchitis (IB) is considered primarily a disease of the respiratory system, different IBV strains may show variable tissue tropisms and also affect the oviduct and the kidneys, with serious consequences. Some strains replicate in the intestine but apparently without pathological changes. Pectoral myopathy has been associated with an important recent variant. Several factors can influence the course of infection with IBV, including the age, breed and nutrition of the chicken, the environment and intercurrent infection with other infectious agents. Immunogenic components of the virus include the S (spike) proteins and the N nucleoprotein. The humoral, local and cellular responses of the chicken to IBV are reviewed, together with genetic resistance of the chicken. In long‐term persistence of IBV, the caecal tonsil or kidney have been proposed as the sites of persistence. Antigenic varia...
202 citations
TL;DR: The results broadly support the view that differences in the sequence of the S1 protein do contribute to the ability of an IBV strain to break through the immunity induced by another strain, and indicate that some conserved sequences in S1 and/or epitopes in the other, less variable, proteins also contribute to immunity.
Abstract: Summary The notion that the S1 subunit of the spike glycoprotein (S) of infectious bronchitis virus (IBV) is the major inducer of protective immunity has been examined. Groups of 10 1‐day‐old chicks were vaccinated with isolate UK/6/82 and challenged in‐tranasally 3 or 6 weeks later with strains whose S1 protein differed from that of UK/6/82 to different extents: NL/D207/79, UK/142/86 and UK/167/84 (2%), UK/123/82 (4%), UK/918/67 (19%), USA/M41/41 and Portugal/322/82 (20%; both of the Massachusetts serotype), and NL/D1466/79 (49%). Four days after challenge tracheas were removed and observed for ciliary activity. Overall, the degree of cross‐protection induced by UK/6/82 diminished as the similarity of the S1 proteins diminished, although in only two cases was the protection induced statistically less (P< 0.10) against the heterologous isolates than against the homologous strain. Even when a group as a whole was poorly protected against heterologous challenge, some individual chicks, including some challe...
162 citations
TL;DR: It is concluded that the RT-PCR described can be used to confirm diagnosis of Newcastle disease within 24 h using RNA isolated directly from tissue homogenate by using the reverse transcrip-tase-polymerase chain reaction (RT- PCR).
Abstract: Fast diagnosis of Newcastle disease is a prerequisite for confining outbreaks. Diagnosis implies the differentation of virulent and non-virulent Newcastle disease viruses (NDV). However, conventional methods, i.e. isolation of the virus and determination of the intracerebal pathogenicity index, take at least 5 days. Therefore, we investigated whether diagnosis can be performed by using the reverse transcrip-tase-polymerase chain reaction (RT-PCR) on RNA isolated directly from tissue homogenate. Two oligonucleotide primers, representing the sequence at the cleavage site of the F protein of either virulent or non-virulent NDV strains, respectively, were used to differentiate NDV. Using the RT-PCR we were able to differentiate 15 NDV reference strains, 11 of which were virulent and 14 non-virulent. The RT-PCR was further validated by using homogenate of brain, trachea, lung and spleen from 12 chicken flocks and one turkey flock suspected of Newcastle disease. The RT-PCR detected virulent NDV in samples of seven flocks and non-virulent NDV in two out of three flocks in agreement with conventional methods. However the RT-PCR failed to detect virus in 1/3 flocks from which non-virulent virus was isolated. The results are discussed. We conclude that the RT-PCR described can be used to confirm diagnosis of Newcastle disease within 24 h using RNA isolated directly from tissue homogenate.
123 citations
TL;DR: Cluster analysis of the mAb binding patterns did not produce concise, discrete groupings, but did emphasise some relationships between virus properties and antigenicity, especially for viruses causing discrete epizootics.
Abstract: Summary Newcastle disease (ND) virus (APMV‐1) isolates submitted to the International Reference Laboratory for ND were characterised antigenically by their ability to cause binding of mouse monoclonal antibodies (mAbs) to cell cultures infected with the isolate. Since the availability of the mAbs 1526 viruses have been examined using a panel of nine mAbs and 818 with an extended panel of 26 mAbs. Using the nine mAb panel a total of 14 different patterns was seen and viruses grouped by the same pattern showed relationships with each other which were either biological, temporal or geographical or more than one of these. There was a marked tendency of viruses placed in the same group to show similar virulence for chickens. Extension of the panel to 26 mAbs produced 39 distinct patterns, although some of these were seen with only a single virus. Again, viruses inducing similar binding patterns shared similar properties and some binding patterns were specific for viruses causing discrete epizootics. Cluster an...
122 citations
TL;DR: The finding that the 793/B isolates could be placed into three subgroups suggests that either (a) they had diverged from a common progenitor present, but undetected, in Britain prior to 1990/91 or (b) at least three different strains of the 7 93/B serotype had entered Britain in or prior to1990/91.
Abstract: Since the winter of 1990/91 respiratory disease of poultry in Great Britain has commonly been associated with the 793/B (or 4/91) serotype of infectious bronchitis virus (IBV). We have sequenced a variable part of the S1 region of the spike protein (5) gene. Comparison of up to 270 nucleotides of 12 British 793/B isolates, obtained in 1991 and 1993, revealed 94 to 100% nucleotide identity with each other. Eleven of them fell into one of two subgroups, A and B, one isolate forming subgroup C. Identity within subgroups A and B was > 98%. The whole S1 gene sequence (1617 nucleotides) was determined for five 793/B isolates, two from each of subgroups A and B and one from subgroup C; nucleotide identity between any two isolates was > 97%. A large proportion of the nucleotide differences corresponded to amino acid changes. The whole S1 amino acid sequence differed by 21 to 25% or more from that of all other published IBV sequences. This extensive difference has probably contributed to the persistence of the 793/B serotype in Britain even though het-erologous vaccines have been used. The finding that the 793/B isolates could be placed into three subgroups suggests that either (a) they had diverged from a common progenitor present, but undetected, in Britain prior to 1990/91 or (b) at least three different strains of the 793/B serotype had entered Britain in or prior to 1990/91.
120 citations
TL;DR: Adding vitamin C to the feed significantly reduced ascites mortality while it had no effect on performance parameters, and plasma thyroid hormone levels were significantly reduced by dietary vitamin C administration, but neither haematocrit nor blood gas levels were influenced.
Abstract: In a two-factorial experiment, 420 1-day-old male commercial broiler chickens were randomly divided and fed a basal diet with or without vitamin C (500 parts/10(6)). Half of the birds within each group receiving the same kind of feed were fed a T(3 )supplemented diet from day 1, in order to increase the ascites incidence. Weekly body weight and feed intake were measured. Venous blood samples were taken from 10 birds per group weekly from day 14 on, for haematocrit measurements, blood gas analysis, measurement of thyroid hormones and lactate/pyruvate ratios. Ascites mortality was recorded daily. Dietary T(3) significantly increased ascites mortality. Adding vitamin C to the feed significantly reduced ascites mortality while it had no effect on performance parameters. Plasma thyroid hormone levels were significantly reduced by dietary vitamin C administration, but neither haematocrit nor blood gas levels were influenced.
72 citations
TL;DR: The results confirm that outbreaks of respiratory disease in turkeys in Britain during 1994 to 1995 were still associated with APV and that the virus was type B.
Abstract: A survey in Britain in 1994/95 has shown that in all cases where avian pneumovirus (APV), was detected in turkeys of over 4 weeks of age, the virus was of type B. Oesophageal swabs were collected twice-weekly for up to 14 weeks in seven longitudinal surveys. RNA was extracted and analysed by reverse transcription-nested polymerase chain reaction designed to discriminate between type A and B APV. Virus of the same type as the vaccinal strain applied (type A or B) was detected from 7 and up to 35 days post-vaccination. Subsequently, type B virus only was detected when the poults were 32 to 67 days old, although in any one growing unit the period of detection was maximally one week. Episodes of increased mortality were usually associated with the detection of this type B virus a few days previously. In a single experiment inoculation of poults with virulent type A or B APV induced cross-protection although that protection was incomplete. Our results confirm that outbreaks of respiratory disease in turkeys in Britain during 1994 to 1995 were still associated with APV and that the virus was type B. In contrast, between 1985 and 1990 only APV antigenically similar to type A and B strains had been detected in Britain and in continental Europe respectively.
60 citations
TL;DR: Lack of clinical signs in neonate chickens was neither due to a failure to respond to the virus, to recruit leukocytes to the infected tissues nor to a lack of viral replication.
Abstract: In situ immunocytochemical staining was used to characterise leukocyte changes and determine tropism of infectious bursal disease virus following infection of neonate and 3-week-old chickens. In the bursae of both groups, massive replication of the virus, a rapid depletion of B cells and an influx of CD4(+) TCR-alphabeta(1)(+) and CD8 (+) TCR-alphabeta(1)(+) cells was detected within 4 days post-inoculation. Leukocyte changes in the spleen, thymus and Harderian gland were similar in both groups. From 8 days post-inoculation onwards all the lymphoid organs became repopulated with leukocytes and tissue architecture began to be slowly restored. Virus neutralizing antibodies developed more slowly in neonate birds and at 21 days post-inoculation the titres were much lower compared to older birds. Lack of clinical signs in neonate chickens was neither due to a failure to respond to the virus, to recruit leukocytes to the infected tissues nor to a lack of viral replication.
53 citations
TL;DR: A natural case of salpingitis, apparently caused by Mycoplasma gallisepticum (MG), in layer chickens is described, characterized by marked thickening of the oviductal mucosa due to epithelial hyperplasia and marked lymphoplasmacytic infiltration.
Abstract: A natural case of salpingitis, apparently caused by Mycoplasma gallisepticum (MG), in layer chickens is described. In the flock from which the chickens originated, there was a 3 to 4% drop in egg production per month around 250 days old. The production was reduced 70% at 400 days of age, which was 77% of the predisease level. Salpingitis was characterized by marked thickening of the oviductal mucosa due to epithelial hyperplasia and marked lymphoplasmacytic infiltration. Colonization of MG on the epithelial surface was evidenced by electron microscopy and immunohistochemistry using rabbit hyperimmune serum against the S6 strain of MG. Antibodies to MG were detected in all the chickens examined..
46 citations
TL;DR: It was shown that S.enterica serovar Tennessee had colonized areas of the hatchers which were protected from routine cleaning and disinfection, and subsequent inclusion of these areas into the sanitation programme resulted in the elimination of S. enterica ser.
Abstract: Summary A substantial increase in the prevalence of 5. enterica serovar Tennessee was observed in broiler flocks in Denmark at the turn of the year 1994 and in the following months. Epidemiological data indicated that a single hatchery was involved in spreading of the infection. Molecular characterization of S. enterica serovar Tennessee isolates from Danish broilers (1992 to 1995), the suspected hatchery and strains from various other sources included for comparison was initiated in order to trace the source of infection of the broilers. In general, strains of S. enterica ser. Tennessee showed only minor genotypic variation. Three different ribotypes were demonstrated when EcoRI was used for digestion of DNA. Two types were obtained by the use of HindIII. Nine different plasmids and seven different plasmid profiles were demonstrated. A 180 kb plasmid was, however, only demonstrated in isolates from broilers and the hatchery. Sixty‐nine per cent of the broiler isolates obtained during the period 1992 to 1...
TL;DR: It is concluded that AGP and ELISA are adequate to detect antibody responses to IBV challenge in both vaccinated and non-vaccinated broilers.
Abstract: Summary Broilers with maternally‐derived immunity (MDI) to infectious bronchitis (IB) were either spray‐vaccinated with H120 at 1 day old, or not vaccinated, then challenged at 28 days with one of four different IBV serotypes. Birds were bled frequently and the sera tested by agar gel precipitation (AGP), haemagglutination inhibition (HI), 2 commercial ELISAs, and virus neutralization (VN) to compare the sensitivity and specificity of the assays. The AGP detected a transient response to challenge with a specificity of 100% and a sensitivity of approximately 40%. The ELISAs showed moderate sensitivity and high specificity with sera from non‐vaccinated broilers, and high sensitivity and variable specificity with vaccinated birds. Depending on the cut‐off value used, the specificity of HI tests was 55 to 100%, while the sensitivity varied widely, making identification of the serotype of an IB challenge unreliable. In vaccinated broilers the sensitivity of the VN tests (used at 21 days post‐challenge only) va...
TL;DR: The programme of antibiotic treatment and competitive exclusion offers an alternative to slaughter, but the approach must be part of a co-ordinated programme which will effect a decrease in the prevalence of 5.
Abstract: Strategic medication in breeding flocks of domestic fowl (Gallus gallus), using antimicrobial treatment followed by competitive exclusion, was evaluated in 13 trials between February and September 1993. In each trial, the flock had been confirmed as naturally infected with Salmonella enterica serovar Enteritidis and the effect of treatment was determined on salmonella isolation from tissues. Of 11 trials where enrofloxacin was used, a long-term reduction of salmonella was observed in two and a short-term reduction was measured in birds from another five trials. Salmonella Enteritidis was isolated from birds after treatment in four other trials with enrofloxacin and in two trials of medication with amoxycillin. After treatment with enrofloxacin significant reductions were found in the prevalence of 5. Enteritidis in tissues from birds, and in levels and prevalence of salmonellas in their environment. No salmonella was identified in statutory meconium samples taken from the hatched chicks derived from the flocks after treatment. The programme of antibiotic treatment and competitive exclusion offers an alternative to slaughter, but the approach must be part of a co-ordinated programme which will effect a decrease in the prevalence of 5. Enteritidis over time by contemporary use of disease security measures. The risk of development of antimicrobial resistance is also discussed.
TL;DR: The impact of aflatoxin on reduced body weights and lower antibody titres was shown to be highly significant (P<0.0001) in chickens using an attenuated live vaccine.
Abstract: A study was conducted on the impact of aflatoxin in the feed on immunization against infectious bursal disease (IBD) in chickens using an attenuated live vaccine. Three-hundred-and-ninety broiler chicks were used. The aflatoxin feeding of 100 and 200 parts/10(9) of AFBI started when chicks were 10 days old and continued for 8 weeks. An attenuated live IBD virus vaccine was administered in drinking water at 2 and 5 weeks of age. A field IBD virus strain was used for challenge. The antibody titres, bursal indices, bursal lymphocyte counts and feed conversion ratios were monitored. The impact of aflatoxin on reduced body weights and lower antibody titres was shown to be highly significant (P<0.0001).
TL;DR: According to the severity of the lesions shown by 1-day-old chicks, the length of the period in which CAV antigen could be detected in tissues, and the fact thatCAV isolate 10343 was capable of inducing disease in 10-week-old chickens, it seems that this CAV isolate may be particularly virulent.
Abstract: Summary One‐day‐old chicks, inoculated intramuscularly (i.m.) with the chicken anaemia virus (CAV) isolate 10343, showed depression of body weight gain and anaemia, particularly between days 14 and 21 post‐inoculation (p.i.)‐ The weights of thymus and bursa were substantially reduced compared to controls at days 14 and 21 p.i. The histological lesions detected in thymus, bursa, spleen and liver were similar in frequency at days 14 and 21 p.i. Eosinophilic intranuclear inclusion bodies, lymphocyte depletion, and focal necrosis were detected in the thymus, spleen, bursa and liver of more than 50% of the inoculated chicks at days 14 and 21 p.i. Focal necrosis and vacuolar degeneration in the liver, as well as apoptosis in different organs were more evident at days 14 and 21 p.i. Ten‐week‐old broiler breeders, inoculated i.m. with isolate 10343 showed pathological changes that were less severe than the changes shown by 1‐day‐old chicks. No anaemia could be detected in this group. However, severe thymus atroph...
TL;DR: The antigenic relationship among 36 IBV strains isolated between 1961 and 1994 from vaccinated and non-vaccinated chicken flocks was determined and it was found that novel strains have not displaced classical strains which continued to be isolated frequently.
Abstract: The antigenic relationship among 36 IBV strains isolated between 1961 and 1994 from vaccinated and non-vaccinated chicken flocks was determined. Based on the reaction with nine monoclonal antibodies (MAbs) in ELISA and polyclonal chicken sera in western blotting, IBV strains clearly fell into two distinct antigenic groups. Nineteen IBV strains isolated between 1961 and 1994 from various locations were antigenically related, having common cross-reactive epitopes on the peplomer S, the nucleocapsid N and the membrane M proteins. IBV strains within this classical group could be antigenically differentiated further by serotyping and by their reaction with MAbs. Seventeen IBV strains isolated between 1988 and 1994, shared only a minor degree of antigenic similarity with strains in the classical group. Strains in this novel group were antigenically related to each other and shared cross-reactive epitopes particularly on the N and M proteins. The novel IBV strains were not detected before 1988 and their origin is unknown. They appeared suddenly and almost simultaneously at two distant commercial sites, Redland Bay and Appin, and were also isolated at a third location in Victoria 3 years later. The Appin strains persisted on the site for 3 years without changes in antigenicity, including the serotype; however, following introduction of vaccination with novel strains a variant of new serotype was isolated. Variants isolated in Victoria on the other hand showed greater antigenic diversity and tendency for change. Novel strains have not displaced classical strains which continued to be isolated frequently.
TL;DR: This is the first recorded isolation of Page serovar C NAD-independent H. paragallinarum in South Africa from poultry showing respiratory manifestations similar to infectious coryza.
Abstract: Summary Since 1990, NAD‐independent bacteria have been isolated in South Africa from poultry showing respiratory manifestations similar to infectious coryza. A total of 126 isolates was examined biochemically and serologically, using polyclonal as well as monoclonal antibodies. Forty isolates were identified as Ornithobacterium rhinotra‐cheale, some of which agglutinated glutaraldehyde‐fixed red blood cells. Furthermore, fourteen Pasteurella avium isolates, five P. volantium and three Pasteurella species A were isolated for the first time. The remaining 64 isolates were biochemically identified as NAD‐independent H. paragallinarum. Of these, 37 were Page serovar A, while no Page serovar B isolates were found. The remaining 25 isolates were typed as Page serovar C. Two different haemagglutination inhibition reaction patterns were found among the Page serovar C isolates, i.e. isolates which reacted with a 1 in 100 dilution of the Page serovar C antiserum, and another larger group which did not react with th...
TL;DR: The results indicate that the feather disease seen in feral Senegal doves in Perth is not due to PsCV although the possibility that it is due to another antigenically distinct circovirus was not eliminated.
Abstract: Summary The pathogenesis and epidemiology of a feather disease in wild Senegal doves (Streptopelia senegalensis) which is morphologically similar to psittacine beak and feather disease (PBFD) was investigated. Although the lesions in doves resembled PBFD there was little evidence for the presence of psittacine circovirus (PsCV). Haemagglutination activity (HA) using type A galah (Eolophus roseicapillus) erythro‐cytes was not detected in feathers or livers of affected doves as would occur in PBFD. Low concentrations of HA excreted in the faeces of affected doves was not caused by psittacine circovirus (PsCV) because the antigen in faeces also caused haemagglutination of PsCV‐insensitive type B galah erythrocyte and was not inhibited by anti‐PsCV antibody. Similar HA of unknown cause was also detected in faeces from clinically normal Senegal doves. Anti‐PsCV haemagglutination inhibiting (HI) antibody was not detected in the serum of affected doves or in the blood of 206 clinically normal wild Senegal doves ...
TL;DR: Proliferative changes with cytoplasmic inclusion bodies in the cornea, bursa of Fabricius, and cranial and nasal bones which were found in the present cases have not been described previously.
Abstract: An epornitic of avian pox occurred in rosy-faced lovebirds (Agapomis roseicollis). The infected birds showed a variety of lesions including cutaneous, diphtheritic, systemic and oncogenic entities. Proliferative changes with cytoplasmic inclusion bodies in the cornea, bursa of Fabricius, and cranial and nasal bones which were found in the present cases have not been described previously. Electron microscopic examination of the skin, cornea, and cranial and nasal bones revealed poxvirus virions in the inclusions. Secondary infection of candidiasis was very common in cutaneous pox lesions.
TL;DR: The nucleotide sequence encoding the HA1 portion of the haemagglutinin gene of the influenza virus A/turkey/Germany/2482/90j isolated from birds kept in an area of many pig farms, was determined and compared with those of recent avian and swine influenza isolates.
Abstract: Summary The nucleotide sequence encoding the HA1 portion of the haemagglutinin gene of the influenza virus A/turkey/Germany/2482/90j isolated from birds kept in an area of many pig farms, was determined and compared with those of recent avian and swine influenza isolates. It was found to be closest to the ‘avian‐like’ swine H1N1 influenza viruses that have been reported in Europe since the early 1980s and may represent good evidence for transmission of these viruses back to birds after they have become established in pigs.
TL;DR: Reactivity of ostrich sera to Newcastle disease virus (NDV) by enzyme-linked immunosorbent assay (ELISA) and haemagglutination inhibition inhibition (HI) test were compared and there was a sigmoidal relationship between antibody levels detected by ELISA and by HI.
Abstract: Summary Reactivity of ostrich sera to Newcastle disease virus (NDV) by enzyme‐linked immunosorbent assay (ELISA) and haemagglutination inhibition (HI) test were compared. Ten‐month old ostriches seronegative by both tests were vaccinated with an oil‐based NDV vaccine on days 0 and 11. Significant levels of reactive antibodies were first detected on day 11 by ELISA (sample/positive ratio > 0.2 in 11/20 birds; 55%) and HI (titre > 1/8 in 10/20 birds; 50%). At the end of the experiment (day 37) all birds had significant antibody levels by ELISA, but only 16/20 (80%) by HI test. There was a sigmoidal relationship (r= 0.62, 3rd degree polynomial) between antibody levels detected by ELISA and by HI test. Antibodies reactive with NDV in naturally exposed ostriches from Zimbabwe and Botswana were also detected by ELISA (112/165; 68%) and HI (85/165; 52%).
TL;DR: It is concluded that MV can be used as a vaccine to render poults resistant to E. coli by evoking antibody production, stimulating the bacterial-lysis activity of complement, stimulating T cells to proliferate and stimulating cytotoxic T cells involved in disease resistance.
Abstract: Summary A vaccine made of bacterial membranes which form vesicles has been developed in our laboratory and found to be effective in protecting chickens against challenge with pathogenic E. coli. In the present study we monitored maternal anti‐5. coli antibody in turkey poults and found that although at hatch the antibody titre was relatively high, it decreased gradually to a low level by 14 days of age and remained low up to 31 days of age. Both intramuscular and subcutaneous vaccination with membrane vesicles (MV) resulted in increased antibody titres. Poults with high antibody titres could survive challenge with the pathogenic bacteria. Serum from vaccinated poults reduced E. coli bacterial growth rate when added to the growth medium at a high concentration, whereas serum from non‐vaccinated poults did not. Lymphocytes from vaccinated poults responded with an increased rate of blastogenesis when MV was added to the cultures. Lymphocytes from non‐vaccinated poults were not stimulated to blastogenesis. We...
TL;DR: The taxonomy of the family Pasteurellaceae Pohl 1981 appears to be as complex as that of Enterobacteriaceae, and 16S rRNA sequencing indicates that the family should be divided into more than 20 genera.
Abstract: Summary The taxonomy of the family Pasteurellaceae Pohl 1981 appears to be as complex as that of Enterobacteriaceae. 16S rRNA sequencing indicates that the family should be divided into more than 20 genera. According to phylogenetic investigations, the genus Pasteurella sensu stricto includes three subclusters, two of which represent taxa mainly associated with avian hosts. True species of the genera Actinobacillus and Haemophilus have not been reported from birds. Several new taxa, which have been shown to belong to the family Pasteurellaceae Pohl 1981 have been reported from birds. Some of these seem to represent genus‐like structures. Due to a high degree of host‐specificity observed for many taxa belonging to the family, the existence of many more species can be foreseen as more avian species are examined. The pathogenesis of Pasteurella infections in birds is poorly understood. However, it has long been recognized that the severity of the disease and its incidence may vary considerably depending on s...
TL;DR: Comparisons of gross and microscopic lesion scores, body weight gains, feed conversion ratios and faecal oocyst counts in chicks showed that under experimental conditions, both duodenal and jejunal microscopicLesion scores regressed with significant linearity on gross lesion Scores.
Abstract: The objective of this study was to apply a microscopic lesion scoring system for assessing the severity of experimental coccidiosis. To accomplish this objective, we examined the effects of varying doses of E. maxima in chicks by comparisons of gross and microscopic lesion scores, body weight gains, feed conversion ratios and faecal oocyst counts. In the battery trial, 3-day-old chicks inoculated with 2.5 x 10(3) or more oocysts had significantly lower growth rate than the controls. The mean feed conversion ratio for days 0 to 36 were significantly greater than those of 0 to 10 and 0 to 17 p.i. The intestinal gross lesion scores and microscopic lesion scores were significantly affected by days p.i. and oocyst dosage. In the floor pen trials, the mean adjusted body weights of 3- and 14-day-old chicks inoculated with 2.5 X 10(4) oocysts of the same strain of E. maxima were significantly lower than the controls. Gross and microscopic lesion scores regressed with significant (P<0.05) linearity on body weight gains. Under experimental conditions, both duodenal and jejunal microscopic lesion scores regressed with significant linearity on gross lesion scores.
TL;DR: The efficacy of enrofloxacin against Riemerella anatipestifer (formerly Pasteurella anatipESTifer) septicaemia of Muscovy and Pekin ducklings was assessed in an artificial challenge model which reproduced typical duck riemerellosis with very high mortality.
Abstract: Summary The efficacy of enrofloxacin against Riemerella anatipestifer (formerly Pasteurella anatipestifer) septicaemia of Muscovy and Pekin ducklings was assessed in an artificial challenge model which reproduced typical duck riemerellosis with very high mortality. Mortality, clinical signs, gross lesions, microbiological clearance, feed intake and body weight gain were the efficacy criteria studied. A pulsing medication in drinking water for 4 h at 25, 50 or 100 ppm enrofloxacin on the first day, followed by 12.5, 25 or 50 ppm, respectively, on the following 4 days, provided clinical cure of R. anatipestifer septicaemia at all dosages tested. An optimum dosage of 50 ppm enrofloxacin, followed by 25 ppm was established.
TL;DR: It appeared that T-cells may play a major role in limiting severity and lethality of IBV infections rather than clearing virus, and the kidney appears to be the primary site ofIBV persistence.
Abstract: Summary Two‐week‐old white leghorn (WL) chickens were inoculated intra‐nasally with 4.51ogio median ciliostatic doses (CD50) of IBV strain M41. Cyclosporin (CSP) (100 mg/kg body weight) was injected intra‐muscularly 3 days before virus infection and every 3 days till day 15 post‐infection (p.i.). Significant reduction in proliferation responses of whole blood lymphocytes to a T‐cell mitogen, concanavalin A were induced, but not to a B and T‐cell mitogen, pokeweed mitogen. Mortality in the IBV + CSP group was 18%, but in the IBV group it was 2%. No significant differences in the total number of virus isolations were seen between the two groups. Virus titres in trachea, lung and kidneys of the T‐cell suppressed chickens were slightly higher and histopathological lesions more severe. Thus it appeared that T‐cells may play a major role in limiting severity and lethality of IBV infections rather than clearing virus. To confirm this, another experiment was performed in which 2‐week‐old brown leghorn (BrL) chick...
TL;DR: An unequivocal diagnosis of aspergillosis was established in all mycotic lesions and the application of immunohistochemistry disclosed fungal fragments in granulomas which could not be identified with conventional histochemical stains.
Abstract: Summary From each of two flocks (A and B) of poults comprising 14,100 females and 11,300 males, respectively, 15 poults were examined pathologically. Poults of flock A had signs of neurological disturbances whereas birds from flock B showed respiratory symptoms. Gross lesions were observed only in two poults from flock A in which minute circular areas of cerebral malaria were seen. Histopathologically, the brain lesions contained fungal elements, and so did some of the pulmonary granulomas detected in three and six poults out of four and six birds examined from flock A and B, respectively. Mycological cultivation was attempted from the brains and lungs of five poults from flock A. However, only from the brain of a single bird a fungus, identified as Aspergillus fumigatus, was grown. Immunohistochemistry was applied because the histomorphology of fungal elements within some lesions did not offer any characteristics allowing an assessment of the identity of the infective fungi. Moreover, as fungi could not ...
TL;DR: Results confirm the necessity of including serovar B regional strains in the formulation of local vaccines and protect against challenge from either the vaccinal strain (H8) or three Argentinean serovars A and C strains (H6, Hll and HI2).
Abstract: Summary Four monovalent experimental vaccines (VI, V2, V3 and V7) containing an Argentinean serovar B strain (H8) of Haemophilus paragallinarum and three different commercial vaccines, either bivalent (V4 and V5) containing serovars A and C, or trivalent (V6) containing serovars A, B and C were administered by subcutaneous or intramuscular routes as a single or double dose (at 3‐week intervals) to chickens of between 6 and 10 weeks. Three to 7 weeks after the last vaccination, vaccinated and non‐vaccinated chickens were challenged by intrasinus inoculation with Argentinean serovar B strains of H. paragallinarum. When the vaccinated chickens were exposed to a severe challenge with the vaccinal strain (H8) some experimental vaccines protected, whereas all commercial vaccines failed to protect. The experimental vaccines manufactured in broth (V2, V3 and V7) protected more effectively than the vaccine produced in chicken embryos (VI). Failure of the commercial trivalent vaccine V6 to protect may be related to...
TL;DR: The results of this study and the frequent shedding of Chlamydia in healthy tits prove that most tits intermittently shedChlamydia sp.
Abstract: Summary A total of 788 cloacal and pharyngeal swabs were taken from 399 free‐living, clinically healthy tits. Ten nestlings were examined by cloacal swabs only. Additionally, six dead tits were necropsied and various organs were collected for testing. All swabs and organ samples were tested for Chlamydia Chlamydia sp. was detected by immunofluorescence with FITC‐conjugated monoclonal antibodies after 90 h incubation on Buffalo‐Green‐Monkey (BGM) cell cultures at 37°C. Fifty‐four per cent of 399 tits examined were Chlamydia positive. Chlamydia was detected in 154 of 399 pharyngeal swabs (39%) and in 144 of 389 cloacal swabs (37%). Blue tits (Parus caeruleus) were most frequently Chlamydia positive (70%), followed by great tits (Pants major) with 53% and marsh tits (Parus palustris) with 38%. No significant relationship was established between Chlamydia detection and time of the year, age, sex or size of birds at the time of sampling. Tits examined two or three times were intermittent shedders. Four of the ...
TL;DR: Free-living condors had total protein, albumin, globulin and Mg values significantly lower than those of captive birds, which may correspond to the optimum values of the species.
Abstract: This study provides information on serology and serum chemistry of the Andean condor (Vultur gryphus). Twenty condors living under natural conditions were captured, blood sampled, measured, and released. In addition, 12 captive condors maintained at the Metropolitan Zoo of Santiago, Chile, were included as a comparison with free-living birds. All sera were negative to antibodies against reference strains of avian paramyxoviruses of serotypes 1 to 9, avian influenza and avian pox virus. Free-living condors had total protein, albumin, globulin and Mg values significantly (P< 0.05) lower than those of captive birds. The haematological values obtained in free-living condors are of particular interest since they may correspond to the optimum values of the species.