Influenza virus subtypes in aquatic birds of eastern Germany

Abstract

We report the findings of a 12-year surveillance study (1977-89) of avian influenza A viruses in eastern Germany. Viruses were isolated directly from feral ducks (n = 236) and other wild birds (n = 89); from domestic ducks (n = 735) living on a single farm; and from white Pekin ducks (n = 193) used as sentinels for populations of wild aquatic birds; mainly sea birds. The efficiency of virus isolation was 9.9% overall, with considerable variability noted among species: 8.7% in wild ducks, 0.9% in other feral birds and 38% in Pekin ducks. Use of sentinel ducks in wild pelagic bird colonies improved virus detection rates fivefold, suggesting that this approach is advantageous in ecological studies. Among the 40 different combinations of hemagglutinin (HA) and neuraminidase (NA) subtypes we identified, H6N1 predominated (23.6% for all avian species), followed by H4N6 (11%). Among individual species, the frequency profiles favored H2N3 (20.8%) and H4N6 (20.3%) in feral ducks; H7N7 (22.3%), H4N6 (24.4%) and H2N3 (10.4%) in Pekin ducks used as sentinels; and H6N1 (34.8%) and H6N6 (15.1%) in domestic ducks maintained on a single farm. By relying on sentinel birds for serological assays, it was possible to trace an "influenza season" in feral swan populations, beginning in August and continuing through the winter months. Comparison of subtype distribution of influenza viruses for Europe and North America showed significant differences. This supports the fact of two geographically distinct gene pools of influenza viruses in birds connected with their distinct flyways of each hemisphere. The high frequency of isolation of H2 influenza viruses is of considerable interest to those interested in the recycling of this subtype in humans. Similarly the frequent isolation of H7N7 influenza viruses raises concern about reservoirs of potentially pathogenic influenza virus for domestic poultry. Our results confirm the existence of a vast reservoir of influenza A viruses in European aquatic birds, which possesses sufficient diversity to account for strains that infect lower animals and humans.

The role of wild birds in the transmission of avian influenza for Australia: an ecological perspective

“…A more useful option might be to focus avian influenza work in wild birds on long-term, longitudinal studies in waterfowl, which share habitat with shorebirds, an approach that has been used elsewhere with very good results (Suss et al 1994). This would give an indication of the spatial and temporal patterns of subtypes entering Australia, and could act to significantly improve understanding of the ecology of these viruses within Australia.…”

“…The chances of detecting avian influenza viruses in shorebirds appears small; however, in other studies, the chance of detection increases 5-fold if waterbirds that are in contact with shorebirds are targeted for surveillance (Suss et al 1994). A number of potential models could be used for surveillance of wild birds.…”

Avian Influenza Viruses and Paramyxoviruses in Wintering and Resident Ducks in Texas

“…Prior exposure and resulting immunity has been suggested as an explanation of the low prevalence of AIV infections in adult ducks versus juvenile ducks (Hinshaw et al, 1985;Webster et al, 1992) and is consistent with our failure to isolate AIVs representing the H3, H4, or H6 subtypes in this study. As evidence suggests that natural infections of AIV do not afford crossprotection between AIV subtypes (Suss et al, 1994), it is possible that wintering ducks would remain susceptible to those subtypes that do not predominate during the premigration and migration periods. The species composition of ducks sampled in this study also may have influenced our results because it is plausible that the infected birds detected in Texas represent birds with little or no previous exposure to AIVs.…”

Effect of biosecurity measures and early detection systems, mitigation measures and surveillance strategies on the spread of HPAI and LPAI between farms

“…The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the rights of the authors. (Süss et al, 1994) Time interval (Swayne, 2006) Study population (Swayne, 2012) Not relevant outcomes Not relevant outcomes Not relevant outcomes (Swayne et al, 2015) Not relevant outcomes (Szeleczky et al, 2010) Not relevant outcomes (Szmaragd et al, 2009) Not relevant outcomes (Tabynov et al, 2014) Not relevant outcomes The present document has been produced and adopted by the bodies identified above as authors. This task has been carried out exclusively by the authors in the context of a contract between the European Food Safety Authority and the authors, awarded following a tender procedure.…”