Two studies find three wild ducks with highly pathogenic bird flu

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    Martin Williams
    Keymaster

    After I posted in Facebook group on Avian Influenza re wild birds unfairly blamed for spreading highly pathogenic bird flu, the group convenor, Hon Ip, posted links to two studies:

    A lesser scaup (Aythya affinis) naturally infected with Eurasian 2.3.4.4 highly pathogenic H5N1 avian influenza virus: Movement ecology and host factors

    //Here, we present telemetry data from a wild Lesser Scaup (Aythya affinis), captured during a separate ecology study in the Chesapeake Bay, Maryland. This bird tested positive for infection with clade 2.3.4.4 HPAI virus of the A/goose/Guangdong/1/1996 (Gs/GD) H5N1 lineage (results received post-release) during the 2021-2022 ongoing outbreaks in North America. While the infected bird was somewhat lighter than other adult males surgically implanted with transmitters (790 g, x̅ = 868 g, n = 11), it showed no clinical signs of infection at capture, during surgery, nor upon release. The bird died 3 days later-pathology undetermined as the specimen was not able to be recovered. Analysis of movement data within the 3-day window showed that the infected individual’s maximum and average hourly movements (3894.3 and 428.8 m, respectively) were noticeably lower than noninfected conspecifics tagged and released the same day (x̅ = 21,594.5 and 1097.9 m, respectively; n = 4). We identified four instances where the infected bird had close contact (fixes located within 25 m and 15 min) with another marked bird during this time. Collectively, these data suggest that the HPAI-positive bird observed in this study may have been shedding virus for some period prior to death, with opportunities for direct bird-to-bird or environmental transmission.//

    Highly Pathogenic Avian Influenza A(H5N8) Clade 2.3.4.4b Viruses in Satellite-Tracked Wild Ducks, Ningxia, China, 2020

    //We attached solar-powered global positioning system satellite trackers to 12 apparently healthy mallards (Anas platyrhynchos) at the capture site and released the birds immediately.

    [[two of these tested positive for highly pathogenic bird flu – H5N8; here’s what happened to them:]

    Satellite tracking showed that 2 mallards (NX-167, negative for AIV, and NX-175, infected with H5N8 virus) migrated to the wintering ground without a long duration in Ningxia. Mallard NX-167 flew directly to Henan at a high speed (82.1–116.2 km/h). In contrast, mallard NX-175 showed a greatly decreased speed (34.1–61.8 km/h) after a short stopover at the junction of Ningxia and Gansu, and eventually reached Gansu (Appendix Figure 1). Another H5N8-infected mallard (NX-176) had been moving around the sampling site until we lost the tracking signals on December 25, 2020 (AppendixFigure 2). These results indicated that mallards could continue to migrate after being infected with HPAI H5N8 viruses, but their movements would be affected.//

    I responded to Hon Ip:

    //Thanks; so that’s three ducks, [one of which just loitered in area not migrating more], two of which did not fly fast and far like regular migrants, one dying within three days …. ….
    Not a lot to base accusations re wild birds as major spreaders on.
    [and where’s the info on the poultry trade, inc Ningxia; any funding available for such studies?!]
    Clearly some vectors into seabird colonies; not clear which they might be, or may be range of species.//

     

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