Outbreak of encephalitic listeriosis in red-legged partridges (Alectoris rufa).

An outbreak of neurological disease was investigated in red-legged partridges between 8 and 28 days of age. Clinical signs included torticollis, head tilt and incoordination and over an initial eight day period approximately 30-40 fatalities occurred per day. No significant gross post mortem findings were detected. Histopathological examination of the brain and bacterial cultures followed by partial sequencing confirmed a diagnosis of encephalitis due to Listeria monocytogenes. Further isolates were obtained from follow-up carcasses, environmental samples and pooled tissue samples of newly imported day-old chicks prior to placement on farm. These isolates had the same antibiotic resistance pattern as the isolate of the initial post mortem submission and belonged to the same fluorescent amplified fragment length polymorphism (fAFLP) subtype. This suggested that the isolates were very closely related or identical and that the pathogen had entered the farm with the imported day-old chicks, resulting in disease manifestation in partridges between 8 and 28 days of age. Reports of outbreaks of encephalitic listeriosis in avian species are rare and this is to the best of our knowledge the first reported outbreak in red-legged partridges.

Demonstration of Ornithobacterium rhinotracheale in pheasants (Phasianus colchicus) with pneumonia and airsacculitis.

Outbreaks of respiratory disease were investigated in reared pheasants (Phasianus colchicus) aged approximately 18 to 32 weeks, released into the semi-wild on four shooting estates in southern England. The clinical signs in the affected birds included swelling of the face and eyes, loss of condition, gasping respirations and coughing. The gross pathology findings included sinusitis, airsacculitis, pleural oedema and lung lesions. The histopathological findings in the affected lungs were characterized by a granulomatous pneumonia. Ornithobacterium rhinotracheale (ORT) was isolated from respiratory tract tissues, and 16S rRNA gene sequencing on three isolates revealed two distinct genotypes, one previously associated with some electrophoretic type (ET) 1 strains and the other a novel genotype that clustered among sequences previously associated with ET 3, ET 4, ET 5 and ET 6 isolates. The localization of ORT within the lung tissue was demonstrated by fluorescent in-situ hybridization in the bronchial exudate of three cases, although not within the granulomatous lesions themselves. In each case, ORT was identified as part of a complex of other respiratory agents including avian paramyxovirus type 2, avian coronavirus, Mycoplasma gallisepticum, Mycoplasma synoviae and other Mycoplasma species, Escherichia coli, Pasteurella multocida, other Pasteurellaceae and Syngamus trachea, suggesting synergism with other agents. Exposure to other intercurrent factors, including adverse weather conditions and internal parasitism, may also have exacerbated the severity of disease.

Congenital tremor and hypomyelination associated with bovine viral diarrhoea virus in 23 British cattle herds.

This paper presents data from 23 British herds investigated between 1991 and 2007 where neurological disease in calves was caused by bovine viral diarrhoea virus (BVDV) infection. A variety of clinical signs, most commonly tremor or trembling, were apparent in the calves from birth, and most were recumbent or unable to stand unsupported. Severe diffuse neuraxial hypomyelination was present in all of the calves, and immunohistochemistry revealed cerebral neuronal labelling consistent with congenital persistent pestivirus infection in each brain. BVDV was detected in peripheral blood samples from eight of 15 calves tested using an antigen ELISA, and was isolated in culture from samples of viscera, brain or blood collected from 17 of 24 affected calves. TaqMan RT-PCR for pestivirus RNA was positive for BVDV-1 in all six calves tested. Six of the virus isolates on which molecular classification was carried out, obtained from calves in four of the herds, were identified as BVDV-1a, while three isolates from one affected and two unaffected calves on a fifth farm were confirmed as BVDV-1b.

Avian encephalomyelitis virus in reared pheasants: a case study.

An outbreak of neurological disease occurred in pheasant chicks on a game farm in 2007. The disease was first seen in the 10th hatching of chicks on the farm. Affected chicks showed trembling and incoordination from the time of hatching, and subsequently blindness and cataract formation was seen in some of the affected chicks at 3 weeks of age. The peak mortality and culling figure was 21.0% in the worst affected hatch, compared with a maximum of 11.7% in the first nine hatches. No further cases were evident by 7.5 weeks of age. Histopathological examination showed a moderate acute encephalomyelitis in some, but not all, of the chicks with neurological signs. The clinical presentation and histopathological findings were typical of vertically transmitted avian encephalomyelitis as seen in chickens, although avian encephalomyelitis virus could not be detected in inoculated embryonated chicken eggs. However, serological testing by enzyme-linked immunosorbent assay for antibodies to the virus was positive in four of five affected 3-week-old birds and in 23 out of 29 adult breeding birds, and reverse transcriptase-polymerase chain reaction testing of RNA extracted from brain and pancreas tissue of affected chicks yielded nucleotide sequences aligned 82% and 83% with three avian encephalomyelitis sequences in a sequence database. The evidence suggested that the neurological disease was attributable to infection with a strain of avian encephalomyelitis virus that appeared to have entered the flock at the start of the breeding season, and was possibly introduced by carrier pheasants brought on to the farm early in the season.

Coronaviruses from pheasants (Phasianus colchicus) are genetically closely related to coronaviruses of domestic fowl (infectious bronchitis virus) and turkeys.

Reverse-transcriptase polymerase chain reactions (RT-PCRs) were used to examine RNA extracted from mouth/nasal swabs from pheasants exhibiting signs of respiratory disease. The oligonucleotides used were based on sequences of infectious bronchitis virus (IBV), the coronavirus of domestic fowl. A RT-PCR for the highly conserved region II of the 3' untranslated region of the IBV genome detected a coronavirus in swabs from 18/21 estates. Sequence identity with the corresponding region of IBVs and coronaviruses from turkeys was > 95%. A RT-PCR for part of the S1 region of the spike protein gene was positive with 13/21 of the samples. Sequence analysis of the RT-PCR products derived from nine of the pheasant viruses revealed that some of the viruses differed from each other by approximately 24%, similar to the degree of difference exhibited by different serotypes of IBV. Further analysis of the genome of one of the viruses revealed that it contained genes 3 and 5 that are typical of IBV but absent in both the transmissible gastroenteritis virus and murine hepatitis virus groups of mammalian coronaviruses. The nucleotide sequences of genes 3 and 5 of the pheasant virus had a similar degree of identity (approximately 90%) with those of coronaviruses from turkeys and chickens, as is observed when different serotypes of IBV are compared. This work: (a) confirms that coronaviruses are present in pheasants (indeed, commonly present in pheasants with respiratory disease); (b) demonstrates that their genomes are IBV-like in their organization; and (c) shows that there is sequence heterogeneity within the group of pheasant coronaviruses, especially within the spike protein gene. Furthermore, the gene sequences of the pheasant viruses differed from those of IBV to similar extents as the sequence of one serotype of IBV differs from another. On the genetic evidence to date, there is a remarkably high degree of genetic similarity between the coronaviruses of chickens, turkeys and pheasants.

Infectious agents associated with respiratory disease in pheasants.

In a case-control study of the infectious agents associated with natural outbreaks of respiratory disease in pheasants, 28 batches of birds from sites affected by disease and eight batches of birds from unaffected sites were examined by six veterinary laboratories in England, Wales and Scotland, and tested for mycoplasmas, other bacteria and viruses. Sinusitis was the commonest sign of disease and was associated with Mycoplasma gallisepticum as detected by PCR in the trachea (P < 0.05) and conjunctiva (P < 0.01). Sinusitis was also associated with pasteurella cultured from the sinus (P < 0.05), antibody to avian pneumovirus (APV) (P < 0.01) and avian coronaviruses as detected by reverse-transcriptase PCR (P < 0.05); there was no association between disease and APV as detected by PCR. Avian coronaviruses were the most common infectious agents detected. They were genetically close to infectious bronchitis virus (IBV) but differed in their gene sequence from all the serotypes of IBV previously identified in domestic fowl, and serological tests with six known IBV types showed little cross reactivity. Mycoplasma species other than M gallisepticum were cultured in 18 batches of pheasants but, with the exception of Mycoplasma gallinaceum, were not associated with disease.

Aleutian disease in domestic ferrets: diagnostic findings and survey results.

Aleutian disease was diagnosed as the cause of posterior ataxia and paresis in domestic ferrets. Six serologically positive animals (four clinically affected and two unaffected) were investigated in detail and seven other clinically affected ferrets were also identified. The diagnostic findings included hypergammaglobulinaemia, histological lesions in the central nervous system and parvovirus-like particles in mesenteric lymph nodes. A wider serological survey of 446 animals owned by members of a ferret club revealed an incidence of 8.5 per cent seropositive animals.