A Lesser Scaup ( Aythya affinis ) Naturally Infected with Eurasian
2.3.4.4 Highly Pathogenic H5N1 Avian Influenza Virus – Movement Ecology
and Host Factors
Abstract
Despite the recognized role of wild waterfowl in the potential dispersal
and transmission of highly pathogenic avian influenza (HPAI) virus,
little is known about how infection affects these birds. This lack of
information limits our ability to estimate viral spread in the event of
an HPAI outbreak, thereby limiting our abilities to estimate and
communicate risk. 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 2021-22 ongoing
outbreaks in North America. While the infected bird was somewhat lighter
than other adult males surgically implanted with transmitters (790g, mean=868g, n=11), it showed no clinical signs of infection at capture,
during surgery, nor upon release. The bird died 3d later, pathology
undetermined as the specimen was not able to be recovered. Analysis of
movement data within the 3d window showed that the infected individual’s
maximum and average hourly movements (3894.3m, 428.8m respectively) were
noticeably lower than noninfected conspecifics tagged and released the
same day (mean =21594.5m, mean =1097.9m, respectively; n=4). We identified four
instances where the infected bird had direct contact (fixes located
within 25m 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. Although limited by low sample size and proximity to the
time of tagging, we hope that these data will provide useful information
as managers continue to respond to this ongoing outbreak event.