Effect of Neospora caninum on in vitro development of preimplantation stage bovine embryos and adherence to the zona pellucida

another study where Cpsittaci isolates from psittacines dominated (Duan and others 1999). No geographical or chronological variation in distribution of serotypes was noted during the observation period. The involvement of only two of six avian serovars correlates with the narrow range of bird orders (Table 3). Serovars C, D and E, frequently isolated from water fowl, turkey and pigeon, were not found. This favourable result is due to a complete lack of intensive duck and goose rearing, only a few turkey fattening units with a maximum of 6000 birds and strict surveillance of imported live birds. Cases of ornithosis in water fowl and turkeys have not been observed over the past 20 years. Therefore, serovars C, usually found in ducks and geese (Vanrompay and others 1993), and D, the serovar associated with the majority of human outbreaks (Andersen 1991), were not found. However, one could argue that these serovars are of lower virulence and, therefore, have been overlooked in this investigation. However, C psittaci-antigen ELISA performed on isolates from choanal and cloacal swabs, histological examinations and in situ hybridisation of a relevant number of unsuspicious cases from water fowl and turkey postmortem revealed no presence of chlamydial antigens or gene sequences. In addition, serological monitoring of blood samples from ducks and turkeys produced negative results during the past five years (data not published). This situation contrasts with observations in turkey flocks from abroad. A serological prevalence of Cpsittaci of between 64 and 90 per cent was reported in Germany and Belgium (Hafez and Sting 1993, Vanrompay and others 1997b). Serovar B strains were found in two bird orders, Psittaciformes and Columbiformes (Table 2). The frequent isolation of C psittaci from pigeons is also reported by other authors (Andersen 1991, Vanrompay and others 1993). Serovar E, which is responsible for 20 per cent of ornithosis outbreaks in American pigeons (Andersen 1997), seems to be rare in Europe (Vanrompay and others 1993, 1997a). No correlation was found between the different isolates and the clinical pictures. All isolates, except one, were from cases that had shown acute onset of disease, a typical postmortem picture with hepatoand splenomegaly and fibrinous aerosacculitis. However, the mean time till death of chicken embryos was delayed significantly in serotype B isolates. Human cases of ornithosis are rare in Switzerland. One confirmed case, related to a psittacine with manifest clinical psittacosis, has been observed during the past five years. Serological monitoring of suspect human cases (such as cases with a history of therapy-resistant pneumonia or influenza) at the Swiss reference laboratory has been negative for C psittaci during recent years (G. Schar, personal communication 1999). These results are based on indirect microimmunofluorescence with a serospecific antibody. All complement fixation-positive human sera originally from suspected cases of ornithosis originated from Chlamydophila pneumoniae infections. Therefore, ornithosis in man is of negligable significance in Switzerland and was recently removed from the Swiss list of notifiable diseases. ACKNOWLEDGEMENTS