Epidemiological and Ornithological Aspects of Outbreaks of Highly Pathogenic Avian Influenza Virus H5N1 of Asian Lineage in Wild Birds in Germany, 2006 and 2007

Abstract

In Germany, two distinct episodes of outbreaks of highly pathogenic avian influenza virus of subtype H5N1 (HPAIV H5N1) in wild birds occurred at the beginning of 2006, and in summer 2007. High local densities of wild bird populations apparently sparked clinically detectable outbreaks. However, these remained restricted in (i) number of birds, (ii) species found to be affected, (iii) time, and (iv) location despite the presence of several hundred thousands of susceptible wild birds and further stressors (food shortage, harsh weather conditions and moulting). Northern and southern subpopulations of several migratory anseriform species can be distinguished with respect to their preference for wintering grounds in Germany. This corroborates viral genetic data by Starick et al. (2008) demonstrating the introduction of two geographically restricted virus subpopulations of Qinghai-like lineage (cluster 2.2.A and 2.2.B) into northern and southern Germany, respectively, in 2006. The incursion of virus emerging in 2007, found to be distinct from the clusters detected in 2006 (Starick et al., 2008), may have been associated with moulting movements. Intensive past-outbreak investigations with negative results of live and dead wild birds and of terrestrial scavengers excluded continued circulation of virus on a larger scale. However, persistence of virus in small pockets of local wild bird populations could not be ruled out resiliently. 1.5% of investigated sera originating from cats sampled at the epicentres of the Ruegen 2006-outbreak contained H5-antibodies. Passive monitoring was found to be highly superior to live bird surveillance when aiming at the detection of HPAIV H5N1 in wild birds (P< 0.0001).

Reversion of PB2-627E to -627K during Replication of an H5N1 Clade 2.2 Virus in Mammalian Hosts Depends on the Origin of the Nucleoprotein

“…occurred on the German island of Rügen, accompanied with high mortality (50,61). Represented by the prototypic isolate A/Swan/Germany/R65/06 (H5N1) (R65) (61), this virus transmitted to 20 different free-living bird species, including mute (Cygnus olor) and whooper swans (Cygnus cygnus), Canada geese (Anser canadensis), and tufted ducks (Aythya fuligula) (17), to a black swan in a zoo (Cygnus atratus) (50), and to poultry (chicken, turkeys) (23). In addition, infection of three stray cats and one stone marten (26,61) To analyze the importance of PB2-627K for the broad host range of H5N1 HPAIV involving several avian and mammalian species, we generated a mutant virus from R65 which carries the avian-specific PB2-627E.…”

Climate change suggests a shift of H5N1 risk in migratory birds

“…HPAI H5N1-infected migratory birds have been found in several European countries, but local outbreaks were smaller in size and intensity compared with the situation observed in China and Southeast Asia (Globig et al, 2009;Ward et al, 2008). This pattern suggests that some wild birds are able to spread AIVs over long distances to previously unaffected areas (Olsen et al, 2006).…”

The Potential Distance of Highly Pathogenic Avian Influenza Virus Dispersal by Mallard, Common Teal and Eurasian Pochard

“…For instance, in Southern Europe, approximately 1-5% of migratory mallard (Anas platyrhynchos) and other dabbling ducks are infected with LP AIV, particularly during winter (De Marco et al, 2003;Lebarbenchon et al, 2007, in press). Although their precise role in the dispersal of highly pathogenic (HP) AIV is still under debate Kilpatrick et al, 2006;Gilbert et al, 2006), observations such as the one that occurred in March 2006 in western Europe suggest that wild ducks have been implicated in recent HP H5N1 outbreaks (Feare, 2007;Globig et al, 2009;Nagy et al, 2009). Governments and the poultry industry therefore need information on migratory duck species that can carry HP AIV to help them take appropriate measures in case of an outbreak, in particular to define a risk area around an outbreak for a period of several weeks.…”