Influenza-A Viruses in Ducks in Northwestern Minnesota: Fine Scale Spatial and Temporal Variation in Prevalence and Subtype Diversity

Abstract

Waterfowl from northwestern Minnesota were sampled by cloacal swabbing for Avian Influenza Virus (AIV) from July – October in 2007 and 2008. AIV was detected in 222 (9.1%) of 2,441 ducks in 2007 and in 438 (17.9%) of 2,452 ducks in 2008. Prevalence of AIV peaked in late summer. We detected 27 AIV subtypes during 2007 and 31 during 2008. Ten hemagglutinin (HA) subtypes were detected each year (i.e., H1, 3–8, and 10–12 during 2007; H1-8, 10 and 11 during 2008). All neuraminidase (NA) subtypes were detected during each year of the study. Subtype diversity varied between years and increased with prevalence into September. Predominant subtypes during 2007 (comprising ≥5% of subtype diversity) included H1N1, H3N6, H3N8, H4N6, H7N3, H10N7, and H11N9. Predominant subtypes during 2008 included H3N6, H3N8, H4N6, H4N8, H6N1, and H10N7. Additionally, within each HA subtype, the same predominant HA/NA subtype combinations were detected each year and included H1N1, H3N8, H4N6, H5N2, H6N1, H7N3, H8N4, H10N7, and H11N9. The H2N3 and H12N5 viruses also predominated within the H2 and H12 subtypes, respectively, but only were detected during a single year (H2 and H12 viruses were not detected during 2007 and 2008, respectively). Mallards were the predominant species sampled (63.7% of the total), and 531 AIV were isolated from this species (80.5% of the total isolates). Mallard data collected during both years adequately described the observed temporal and spatial prevalence from the total sample and also adequately represented subtype diversity. Juvenile mallards also were adequate in describing the temporal and spatial prevalence of AIV as well as subtype diversity.

The enigma of the apparent disappearance of Eurasian highly pathogenic H5 clade 2.3.4.4 influenza A viruses in North American waterfowl

“…LP H5 IAVs are routinely detected in wild waterfowl, but other than this recent event, no HP H5 or H7 IAVs have been detected in any wild birds in North America over the past 43 y. H5 IAV does not represent a predominant subtype in either historical (14) or recent surveillance (Table 2); however, when LP H5 viruses are detected, they most commonly occur paired with N2 (H5N2), and this combination appears to be consistent in wild birds of both North America and Eurasia (15). Thus, it might not be surprising that the HP Eurasian H5/North American N2 reassortant not only occurred early in this outbreak, but also was the most detected HA-NA combination isolated from both wild birds and poultry (Fig.…”

“…Numerous IAV subtypes are maintained in North American waterfowl, but H3 and H4 subtypes are predominant, especially during fall migration (14,15). Long-term surveillance of IAVs in migratory waterfowl has demonstrated higher infection rates in juvenile ducks compared with adult ducks (23) along with a cyclic dominance of subtypes, with one subtype dominating for 2 y, followed by replacement with another subtype.…”

Reassortant influenza A viruses in wild duck populations: effects on viral shedding and persistence in water

“…Isolates were obtained from an ongoing long-term surveillance of IAV circulation in wild birds in Minnesota, USA [27]. In this study, five viruses isolated from dabbling duck Relative abundance of the five virus subtypes (i.e.…”

“…prevalence + 95% confidence intervals) in the waterfowl population at the sampling site was 22.5 + 9.7% (H3N8), 9.9 + 6.9% (H6N1), 5.6 + 5.4% (H6N2), 2.8 + 3.9% (H6N8) and 1.4 + 2.7% (H4N8) (cf. [27] for details).…”

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

“…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.…”