Virological monitoring of white storks (Ciconia ciconia) for avian influenza

Between 2003 and 2008, more than 600 white stork (Ciconia ciconia) nestlings in the German federal state of Brandenburg were ringed and examined for influenza A viruses. With the spread of highly pathogenic avian influenza virus (HPAIV) of subtype H5N1 among wild birds in Germany in spring 2006, dead wild birds, including 88 white storks, were tested for infection with HPAIV. Furthermore, fresh fecal samples were examined by RT-PCR to monitor the occurrence of HPAIV in adult storks. While the monitoring of nestlings and adult white storks failed to yield evidence of influenza A virus infections in these birds, two storks found dead in April 2006 in the same location tested positive for HPAIV H5N1. Sequence analysis revealed that the virus isolated from one of the storks belonged to clade 2.2, which was commonly found in wild birds in the north of Germany and other European countries during the epidemic in 2006. Despite these two cases, white storks seemed to serve as neither a vector nor as a reservoir for HPAIV in Germany. The risk of white storks transmitting HPAIV to domestic poultry and humans is low.

A Virological Survey in Migrating Waders and Other Waterfowl in One of the Most Important Resting Sites of Germany

Wild birds are considered a potential reservoir or a carrier of viral diseases and may therefore play a role in the epidemiology of economically important or zoonotic diseases. In 2001 and 2002, a survey with special emphasis on virus isolation in migrating waders and some other birds were conducted. In one of the most important inland resting sites for migratory waterfowl, tracheal and cloacal swabs were collected from 465 waders representing 19 different species, and 165 other birds that were not captured on purpose. A total of 42 avian viruses were isolated, 34 of these were identified as paramyxoviruses (PMVs). The majority of isolates came from waders and wild ducks, and were characterized as PMV-1. In contrast, PMV-4 was found in wild ducks only, PMV-6 was mainly detected in wader species. Four avian influenza viruses (AIVs), belonging to H4 and H3 haemagglutinin subtype, were isolated from wild duck species. Furthermore, four reo-like viruses were isolated from one particular wader species for the first time. The majority of virus positive birds were <1 year old and did not show any clinical symptoms. There was no evidence for the presence of West Nile virus in these birds. These results confirm that the restricted resting sites in Western Europe must be considered as important locations for the intra- and interspecies transmission of avian viruses.

A descriptive analysis of the potential association between migration patterns of bean and white-fronted geese and the occurrence of Newcastle disease outbreaks in domestic birds

The sightings and migration patterns of 65 bean (Anser fabalis) and 65 white-fronted geese (Anser albifrons) are reported. In the past, these geese were serologically screened for the occurrence of Newcastle disease virus (NDV) and other avian viral diseases by Hlinak et al. (3). Of the 130 birds originally tagged and serologically screened in 1991, 53 birds were resighted between 1991 and 1996. Most of the sightings were reported from main wintering and resting sites in Germany and The Netherlands. It is noteworthy that 19 of the 53 birds sighted had serologic evidence that they had been exposed to NDV before the time of marking in 1991. Although the origin of these infections in bean geese and white-fronted geese is still unknown, the sightings reported in this study indicate that, once infected, wild geese may be involved in the dissemination and spread of avian viral diseases, specifically Newcastle disease. The migration patterns of the wild geese provided further evidence that the main resting and wintering areas of migratory waterfowl are likely to be important for the inter- and intraspecies transmission of avian diseases, thereby representing risk areas for the poultry industry.

Serological survey of viral pathogens in bean and white-fronted geese from Germany

Sera from wild geese were tested for antibodies to selected viral pathogens at a resting site for wild waterfowl in Germany. Serum samples from both bean geese (Anser fabalis) and white-fronted geese (Anser albifrons) collected in October 1991 were examined using serological methods licensed for routine diagnosis in domestic poultry. Of 130 sera tested, antibodies to several infectious agents were found including Newcastle disease virus (45%), goose parvovirus (48%), avian reovirus (29%), and avian adenovirus or egg drop syndrome 76 virus (6%). Antibodies against duck hepatitis virus were not detected. Differences in seroprevalences were not detected between the two geese species. While role and significance of wild geese in the epidemiology of avian diseases remains to be determined, it is possible that they could be of some importance as reservoirs and carriers of certain viral diseases of domestic poultry.