Avian influenza detected in mammals in sub-Antarctica for the first time

The presence of High Pathogenicity Avian Influenza (HPAI) has been confirmed for the first time in mammals in sub-Antarctica.

The disease was detected in elephant and fur seals on the island of South Georgia by experts from the UK’s Animal Plant Health Agency (APHA).

Working alongside the Government of South Georgia and South Sandwich Islands (GSGSSI) and the British Antarctic survey (BAS), APHA has been at the forefront of testing for bird flu in mammals in this sub-Antarctic region since it was first suspected last year. 

Seabird colonies

South Georgia is a UK Overseas Territory situated in the Southern Atlantic Ocean, approximately 1,000km south-east of the Falkland Islands, and is accessible only by ship. It has some of the most closely monitored seabird colonies in the world, equipping scientists and conservationists with indicators of change for species.

HPAI was first suspected on Bird Island off the northwest coast of South Georgia in October 2023 after the deaths of several brown skua. Sequence analysis from infected birds demonstrates that the virus has most likely been introduced through migratory bird movement from South America.

Leading APHA scientist Dr Marco Falchieri of the Influenza and Avian Virology team spent three weeks in the sub Antarctic region visiting the affected islands onboard Royal Navy vessel HMS Forth and collected samples from dead mammals, including elephant seals, and birds.

Following testing and sequencing at APHA’s laboratory in Weybridge, the samples have tested positive for HPAI H5N1 in elephant seals, fur seals, brown skuas, kelp gulls and Antarctic terns.

Genomic surveillance

Samples were also collected from albatross and giant petrel colonies on Bird Island but tested negative. There have been no reports of above average mortality in any penguin species to date.

The available genomic surveillance data continues to suggest no widespread mammalian adaptation of the virus. There remains no increased risk to human health - the risk of human infection with H5N1 remains very low.

Professor Ian Brown, APHA’s Director of Scientific Services, said: “Given Antarctica is such a unique and special biodiversity hotspot it is sad and concerning to see the disease spread to mammals in the region. 

“If avian influenza continues to spread throughout the sub-Antarctic region this could significantly threaten the fragile ecosystem, and potentially put a number of very large populations of seabirds and sea mammals at risk.

Global risk mitigation

“However, the available genomic surveillance data continues to suggest no widespread mammalian adaptation of the virus and the knowledge gathered from these latest samples will be shared rapidly with international partners to aid their efforts to tackle the disease and inform global risk mitigation. Uncertainties remain as to how the virus is infecting and spreading amongst these populations. APHA will continue to work with the Government of South Georgia and South Sandwich Islands, the Falkland Islands and the British Antarctic Survey to monitor the impact of the wildlife on South Georgia, and the potential spread to other areas.”

BAS operates two research stations on South Georgia: King Edward Point and Bird Island. As a result of the confirmed cases of HPAI, most fieldwork involving contact with animals has been suspended. BAS staff are following the additional biosecurity measures adopted this season of enhanced cleaning of clothing and field equipment when moving between sites with high densities of wildlife, as well as remaining vigilant for signs of disease.

Long-term monitoring

Key elements of the wider science programme at King Edward Point and Bird Island continue under caution, including long-term monitoring of wandering albatross, black-browed albatross, grey-headed albatross, northern and southern giant petrels, gentoo penguins and macaroni penguins.

Ash Bennison, science manager for Bird Island Research Station, said: “It’s incredibly sad to witness the effects of avian flu on the animal populations we study on South Georgia.

“We are doing everything we can to mitigate the effects of this disease and are working closely with the Government of South Georgia and South Sandwich Islands and the Animal and Plant Health Agency to continue our work to monitor and conserve these amazing species.”

Ongoing support

Laura Sinclair Willis, Chief Executive, Government of South Georgia & the South Sandwich Islands, said: “The Government of South Georgia and the South Sandwich Islands anticipated that High Pathogenicity Avian Influenza would likely arrive on our shores in the 23/24 austral summer, and we are grateful for the ongoing support of the Animal and Plant Health Agency, British Antarctic Survey, Ministry of Defence and the Antarctic cruise industry, along with a global community of partners and stakeholders who are helping us to monitor the impacts within the Territory.

“The transmission and spread of this disease is primarily a natural phenomenon, and we continue to emphasise the importance of scrupulous biosecurity by all those entering South Georgia and the South Sandwich Islands.”

News of concern

Dr Sarah Pitt, Applied Microbiology International member; chief examiner in virology at the Institute of Biomedical Science; and microbiologist at the University of Brighton, commented: “It is of concern that HPAI has been detected in aquatic mammals and birds in sub-Antarctica.  The Team at APHA have conducted detailed analyses of the virus samples taken from the wildlife.  It shows that some birds in that region can be infected with avian influenza.  However it is worth noting that there no evidence for presence of the virus in some of the species of bird investigated. 

“The report suggests that only dead seals were tested, so the extent of the problem in the seal population is not known (so it is a qualitative result, showing that seals can be infected and affected by the virus).

 “It is good that there is no indication of risk for humans from this strain of avian influenza.  This is consistent with evidence from other outbreaks of HPAI in other parts of the world.”

This work follows the announcement of an additional £3.3 million from UK Research and Innovation’s (UKRI) Tackling Infections programme and the Department for Environment, Food and Rural Affairs (Defra) granted to our FluMap project. The new project, FluTrailMap, will respond to the evolving nature of avian influenza and further our understanding of:

• transmission and infection in different bird populations, including how the virus transmits from wild birds to farmed poultry
• the gaps in biosecurity that allow the virus to penetrate premises, and how they may be addressed
• the role of immunity in wild birds in the evolution of the virus
• how the implementation of vaccination might impact upon outbreaks