Erik Uyttebroek

Streptococcus bovis infections in pigeons.

Streptococcus bovis infection was diagnosed in pigeons from 20 lofts submitted for post mortem investigation. Clinical signs were very variable and ranged from hyperacute death to chronic lameness with arthritis. Lesions were generally unspecific except for single cases of muscle necrosis with purulent myositis. Histological examinations demonstrated the septicaemic nature of the infections. Intravenous inoculations of S. bovis resulted in prostration, long lasting loss of weight and polyuria. Microscopically purulent hepatitis and nephritis were the most characteristic lesions. After oral inoculation no clinical signs were seen.

Epidemiology and significance of chicken infectious anemia virus infections in broilers and broiler parents under nonvaccinated European circumstances.

A serologic survey in unvaccinated broiler parent and broiler progeny flocks demonstrated seroconversion against chicken infecrious anemia virus (CIAV) in all parent flocks before or around point of lay and in 38% of the broiler flocks examined at slaughter age. The presence of CIAV antibodies at slaughter of broilers was positively correlated with slaughterhouse condemnation rates. Results indicate that CIAV infections are highly prevalent in both broiler parent and broiler flocks and that CIAV infections in broilers are associated with increased slaughterhouse condemnation.

Reovirus serology in broiler parents and their progeny and its correlation with performance.

An intensive vertically integrated monitoring program for broiler breeders and their offspring was set up in a Belgian poultry integration between 1993 and 1997. Serology for anti-reovirus antibodies was performed by enzyme-linked immunosorbent assay on blood samples taken from the broiler parents throughout rearing and production and also on blood samples taken at day-old and at slaughter from the broilers. Furthermore, production parameters of the birds were registered. All data were used two by two in a simple correlation study to calculate the degree to which these variables were linearly correlated. The reovirus antibody pattern indicated frequent field infections breaking through vaccinal immunity in the broiler parents. Under the epidemiologic conditions of this study, high antibody titers in the parents or in the broilers at day-old were significantly correlated with poor feed conversion, increased mortality, increased slaughterhouse condemnation, and low production score in the broilers. These correlations strongly support the view that reovirus infections can be economically important under European conditions of broiler production. Improvement of reovirus vaccines or the vaccination scheme in broiler parents or both may lead to better production results in the broiler offspring.

SUSCEPTIBILITY OF HARES AND RABBITS TO A BELGIAN ISOLATE OF EUROPEAN BROWN HARE SYNDROME VIRUS

Signs and pathologic changes of European brown hare syndrome (EBHS) were reproduced in four hares (Lepus europaeus) after experimental inoculation of a liver suspension from hares from Belgium, which naturally died of EBHS. Virus particles were demonstrated by electron microscopy in the liver of an experimentally infected hare. They were spherical with a diameter of 28 to 30 nm. After density gradient centrifugation, virus particles were detected in the density zone of 1.34 g/ml. Based on immunoelectron microscopy with a convalescent serum, we identified the virus as the cause of EBHS. Clinical signs were not produced in three seronegative domestic rabbits after subcutaneous inoculation of the EBHS virus. Although low levels of antibodies against EBHS virus were found in the serum of these three rabbits 4 weeks after the inoculation of EBHS virus, the rabbits were not protected when challenged with viral hemorrhagic disease (VHD) virus. The different pathogenicity of the Belgian EBHS and VHD virus isolates in rabbits and the lack of protection in rabbits with circulating EBHS virus antibodies against a challenge with VHD virus indicates that both Belgian virus isolates form two different virus populations.

Respiratory adenovirus-like infection in a rose-ringed parakeet (Psittacula krameri).

Intranuclear inclusions were observed under light microscopy in the bronchial epithelial cells of a recently purchased female rose-ringed parakeet that died of chlamydiosis. Transmission electron microscopy revealed the presence of numerous particles of adenovirus morphology. A latent adenovirus infection may have become more severe following chlamydiosis and the stress of handling.

Three cases of infection by haemophilus‐like bacteria in psittacines

The clinical manifestations of three cases of infection with NAD (V-factor)-requiring Haemophilus-like bacteria in psittacines are described. Case 1 involved members of the Platycercus family and produced mainly respiratory signs. In case 2 only conjunctivitis was seen among cockatiels. The third case was a hand-reared African grey parrot which developed a peracute septicaemia. The Haemophilus-like bacteria isolated from the three cases differed from each other as well as from the known avian NAD-requiring Haemophilus and Pasteurella species.

Staphylococcus hyicus associated with pox in chickens and in turkeys

Staphylococcus hyicus was isolated in profuse and often pure culture from skin lesions, and from internal organs of chickens and turkeys suffering from pox. Most cases were seen in backyard stock, but similar observations were made in laying hens from an industrial farm.

Significance of Infectious Bursal Disease Serology in an Integrated Quality Control Program Under European Epidemiologic Conditions

In this study performed between 1993 and 1997, infectious bursal disease virus (IBDV) antibody titers and performance data were recorded in a vertically integrated monitoring scheme in order to make a follow-up from day-old parents down to the broilers at slaughter. All measured data were used two by two in a simple correlation study to calculate the degree to which they were linearly correlated. It appeared that high and/or uniform antibody titers in the parents were correlated with increased daily weight gain and decreased mortality and slaughterhouse condemnation in the broilers. Antibody titers and their CVs were negatively correlated in broiler parents and their offspring at day-old and even at slaughter. Results indicate that high and uniform antibody titers against IBDV in broiler parents are important for good performance of the broiler offspring, at least under the epidemiologic conditions of this study, which included the presence of very virulent IBDV strains in the field and the sole use of live intermediate vaccines in broilers as well as broiler parents.

Taxon 20 (Fam. Pasteurellaceae) Infections in European Brown Hares (Lepus europaeus)

Hemolytic bacteria, phenotypically related to organisms previously identified as Pasteurella haemolytica and tentatively named Taxon 20, were isolated from cases of purulent bronchopneumonia and from conjunctivitis in European brown hares (Lepus europaeus). The bronchopneumonia, sometimes accompanied by lesions in other organs, occurred without other concomitant disease. The conjunctivitis was found mainly in animals suffering from the European brown hare syndrome.