Environmental Samples Test Negative for Avian Influenza Virus H5N1 Four Months after Mass Mortality at A Seabird Colony

Abstract

High pathogenicity avian influenza (HPAI) profoundly impacted several seabird populations during the summers of 2021 and 2022. Infection spread rapidly across colonies, causing unprecedented mortality. At Foula, Shetland, 1500 breeding adult great skuas Stercorarius skua, totalling about two tonnes of decomposing virus-laden material, died at the colony in May−July 2022. Carcasses were left where they died as Government policy was not to remove dead birds. The factors influencing risk of further spread of infection are uncertain, but evidence suggests that HPAI can persist in water for many months in cool conditions and may be a major transmission factor for birds living in wetlands. We investigated risk of further spread of infection from water samples collected from under 45 decomposing carcasses and in three freshwater lochs/streams by sampling water in October 2022, by which time the great skua carcasses had rotted to bones, skin, and feathers. No viral genetic material was detected four months after the mortality, suggesting a low risk of seabird infection from the local environment when the seabirds would return the next breeding season. These findings, although based on a relatively small number of water samples, suggest that the high rainfall typical at Shetland probably washed away the virus from the decomposing carcasses. However, limitations to our study need to be taken on board in the design of environmental monitoring at seabird colonies during and immediately after future outbreaks of HPAI.

Detection and spread of high pathogenicity avian influenza virus H5N1 in the Antarctic Region

“…In the autumn of 2021, the situation escalated considerably with the detection of a clade 2.3.4.4b HPAIV subtype H5N1 in Europe 2 . Subsequently, two unprecedented epizootic waves with this lineage in 2021/22 and 2022/23 were associated with mass mortality events in wild birds together with unprecedented numbers of incursions into poultry premises 2, 3, 4, 5, 6 . High levels of viral adaptation to wild bird species 7 , and increased fitness advantage through continued genetic reassortment 8 likely underpin the broad impact infection has had across many avian species 3 .…”

Confirmation of Highly Pathogenic Avian Influenza (HPAI) H5N1 Associated with an Unexpected Mortality Event in South Polar Skuas (Stercorarius maccormicki) during 2023-2024 Surveillance Activities in Antarctica

“…The confirmation of HPAI H5N1 in skua species in the other locations, as well as its apparent smaller population observed at the season at Fildes Peninsula, could suggest this species could present higher susceptibility of HPAI H5N1 compared to other Antarctic species. Other skua species such as Great skua have been confirmed positive for HPAI H5N1, and even a massive mortality event has been documented at Foula Island, United Kingdom (Furness et al, 2023; Lean et al, 2023). On the other hand, as top predators, and scavengers devoid of natural enemies, and with widely spaced nests due to territorial behavior, Antarctic skuas likely present a reduced risk for rapid virus dissemination between them.…”

Rapid mortality in captive bush dogs ( Speothos venaticus ) caused by influenza A of avian origin (H5N1) at a wildlife collection in the United Kingdom

“…Genetic assessment from tissues positive for each animal was undertaken to try and evaluate the possibility of dog-to-dog transfer. Local atmospheric conditions are known to influence environmental virus survival with lower temperatures promoting persistence [ 18 , 32 ]. In early October 2022, the day-night high-low temperature range near this site was 17–11°C.…”

“…For samples collected on 17–22 November 2022 and 06 March 2023, day-night readings were consistent at 8–11°C and 4–8°C respectively, hence favourable to virus survival. Other factors can impact the detection of environmental vRNA from water, dilution (rain), volume (lake) and flowrate (river) [ 32 ]. This might account for a single M-gene signal detection from the bush dog water trough (17/11/2022) (Supplementary Table 3).…”