Long-term variation in influenza A virus prevalence and subtype diversity in migratory mallards in northern Europe

Abstract

Data on long-term circulation of pathogens in wildlife populations are seldom collected, and hence understanding of spatial-temporal variation in prevalence and genotypes is limited. Here, we analysed a long-term surveillance series on influenza A virus (IAV) in mallards collected at an important migratory stopover site from 2002 to 2010, and characterized seasonal dynamics in virus prevalence and subtype diversity. Prevalence dynamics were influenced by year, but retained a common pattern for all years whereby prevalence was low in spring and summer, but increased in early autumn with a first peak in August, and a second more pronounced peak during October-November. A total of 74 haemagglutinin (HA)/neuraminidase (NA) combinations were isolated, including all NA and most HA (H1-H12) subtypes. The most common subtype combinations were H4N6, H1N1, H2N3, H5N2, H6N2 and H11N9, and showed a clear linkage between specific HA and NA subtypes. Furthermore, there was a temporal structuring of subtypes within seasons based on HA phylogenetic relatedness. Dissimilar HA subtypes tended to have different temporal occurrence within seasons, where the subtypes that dominated in early autumn were rare in late autumn, and vice versa. This suggests that build-up of herd immunity affected IAV dynamics in this system.

Spread and Persistence of Influenza A Viruses in Waterfowl Hosts in the North American Mississippi Migratory Flyway

“…The degree of host population immunity is an important driver of the diverse AIV antigenic subtypes that dominate regional sites from year to year (54). For example, antigenic drift likely results in the absence of similar HA gene lineages (i.e., AIV surface protein ¡ host immunity target) across migratory seasons at the regional sites observed in this study (55).…”

Narrative overview on wild bird migration in the context of highly pathogenic avian influenza incursion into the European Union

“…High effort longitudinal sampling of Mallards at a stopover site in Sweden has shown that the majority of the seasonal variation can be accounted for in epidemiological models (Latorre-Margalef et al, 2014). In Figure 2B, LPAIV prevalence over time is depicted at a stopover site in Sweden.…”

“…From longitudinal sampling of LPAIV in Mallards and other dabbling ducks conducted in Europe we know that virus prevalence follows a seasonal pattern, whereby the prevalence is low during the late winter, spring, and summer, followed by a peak in viral prevalence during the autumn migration (Ito et al, 1995;Hatchette et al, 2004;Olsen et al, 2006;Wilcox et al, 2011;Latorre-Margalef et al, 2014). This pattern has been observed at a number of study sites across the Northern Hemisphere, including Sweden (Latorre-Margalef et al, 2014), The Netherlands van Dijk et al, 2014) , Canada (Alberta, (Sharp et al, 1997;Hatchette et al, 2004)), USA (e.g.…”

Dynamics of low and high pathogenic avian influenza in wild and domestic bird populations

“…Influenza A viruses can infect many species of warm-blooded vertebrates [26], but the great majority of viral strains appear to be found in wild waterbirds, such as shorebirds and gulls (Charadriiformes) and ducks and geese (Anseriformes) [12]. These species can come into contact with domestic poultry, which can pose a direct threat to the poultry industry, and also provide a conduit for potential transmission to humans.…”