Monitoring of West Nile virus infections in Germany.

The research aims to observe the presence of the West Nile Virus (WNV) in wild birds, domestic poultry, and horses in Germany, through serological and molecular screenings during the years 2009-2011. While the prevalence of the virus was found in some migratory birds, there was no clear evidence of the virus in resident birds, domestic poultry, or local horses.

About the West Nile Virus (WNV)

• The West Nile Virus (WNV) is a type of flavi virus that typically circulates between birds and mosquitoes, with variants of the Culex genus being the main transmitters.
• Some bird species, like ravens, jays and raptors, are particularly susceptible to this virus, and may develop fatal encephalitis as a result of infection.
• Other species experience subclinical infections whereby they host the virus without showing any signs of illness.

Research Methodology

• The research involved serological and molecular screenings on wild birds, domestic poultry, and horses in Germany from 2009 to 2011, and expanded on previous research. All three groups serve as indicators for the circulation of WNV.
• The presence of WNV-specific antibodies was determined by using a virus neutralization test (VNT), indirect immunofluorescence test (IFT), and an enzyme-linked immunosorbent assay (ELISA).
• Additionally, the presence of WNV genomes was tracked in relevant samples using two qRT-PCRs directed to amplify lineage 1 and 2 strains.
• In total, 364 wild bird serum samples, 1119 samples from domestic poultry, and 1282 samples from horses were examined.

Findings and Conclusion

• Antibody carriers, barring one hooded crow, were found only in migratory birds.
• There was no detectable presence of WNV-specific nucleic acids in any of the samples, indicating that there was no direct presence of the virus in the subjects.
• The study concluded that there is no convincing evidence for indigenous WNV infections in horses and in wild/domestic birds in Germany.
• However, as WNV infections are now endemic in other European countries (Austria, Hungary, Greece and Italy), the research advocates for an efficient surveillance system in Germany, to monitor potential incursions of WNV.