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Scientists react to the detection of avian influenza in mammals in the sub-Antarctica region.
Dr Kathleen Steinhöfel, a Reader in Computer Science at King’s College London, said:
“The press release reflects quite accurately on this case of detection of H5N1. And while this is a natural phenomenon, more study is needed to understand how this disease first infected the elephant and fur seal population. The samples will need further analysis to see what mutations allowed the disease to spread to other species. The data collected so far, suggests isolated cases of infection due to contact with wild birds rather than a mammalian transmission.”
Prof Rowland Kao, Professor of Veterinary Epidemiology and Data Science, University of Edinburgh, said:
“This report follows the narrative of HPAI H5N1, spreading progressively throughout the world, often (as in this case) to previously unexposed animal populations. The underlying causes for this are still a subject of active research, though there is evidence of some properties of the virus itself that may change transmission patterns. Throughout, the exposure of naive bird and mammal populations has resulted in mass mortalities in many species, some at conservation risk.
“It’s important to stress that here as in most cases worldwide, transmission to mammals is likely the result of scavenging by the mammal populations on infected dead birds, and represent minimal risk of further spread (e.g. to humans) with little indication that changes making it a virus adapted to humans are likely. Despite this, where there are infected birds and mammals there is a risk, albeit low, to humans of getting infected with H5N1, so people are advised to avoid direct contact with dead birds and mammals found in the wild, anywhere that avian influenza is a likely cause.”
Dr Sarah Pitt, Applied Microbiology International member; chief examiner in virology at the Institute of Biomedical Science; and microbiologist at the University of Brighton, said:
“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 to 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.”
Dr Alastair Ward, Associate Professor of Biodiversity and Ecosystem Management; Programme Lead for Zoology, University of Leeds, said:
Does the press release accurately reflect the science?
“Yes. This was a simple survey of found-dead animals to detect the virus. The same team routinely conducts this sort of surveillance throughout the UK.
Is this based on good quality research? Are the conclusions backed up by solid data?
“Yes.
How does this work fit with the existing evidence?
“Highly pathogenic avian influenza was detected in captive European mink in northern Spain in October 2022, and in otters and foxes in southern England soon after. During 2023 it was detected in seals and sea lions around Europe and the Americas, and most recently in an Alaskan polar bear. Considering the breadth and geographical distribution of species affected to date, this new discovery of the same strain in seals and seabirds found dead on South Georgia is perhaps unsurprising, but it is extremely saddening.
Are there important limitations to be aware of?
“Finding highly pathogenic avian influenza in several individuals of the same species of mammal does not necessarily mean that the virus has been spreading between individuals within that species. The number of seabirds dying with avian influenza in some colonies has been very high and deaths have been rapid. It seems feasible that mammals, such as seals, that are known to scavenge, may become infected when they consume infected bird carcasses.
What are the implications in the real world? Is there any overspeculation?
“Perhaps the greatest concern is for bird conservation. South Georgia, and Bird Island in particular is renowned for being home to large colonies of southern giant petrels, several species of albatross and two species of penguin. Declines of bird populations on these islands would constitute a great loss to local ecosystem functioning and also to the world’s biodiversity.
Is this worrying or expected? Does this change anything about the risk to humans?
“Considering the breadth and geographical distribution of bird and mammal species affected by highly pathogenic avian influenza to date, this new discovery of the same strain in seals and seabirds found dead in Antarctica is perhaps unsurprising, but it is extremely saddening. Very specific changes are needed within the virus’s genome that make it better adapted to a human host; these changes have not been detected in samples taken from wild birds or mammals to date, so the risk to humans likely remains low. Nevertheless, these viruses are highly adaptable, so it would be wise to maintain surveillance programmes so that we can detect new variants as they emerge and hence respond appropriately in good time if it becomes necessary to do so.”
Dr Matthew Dryden, Consultant in Infection, UK Overseas Territories Program, said:
“The FCDO funded UK Overseas Territories Program which is part of UKHSA works closely with the Government of South Georgia and South Sandwich Islands (GSGSSI) and the British Antarctic survey (BAS) and APHA to give public health and clinical advice. Although it is sad that HPAI has reached the south Atlantic and is affecting wildlife including some mammals, this was anticipated following the outbreaks in the northern hemisphere where mammals have also been affected. Genomic sequencing of the virus suggests that there is no mammal to mammal transmission. In other words, the seals are acquiring the virus from sick birds on land. With the strong biosecurity measures in place, there is no risk to human health at present and the situation continues to be monitored closely.”
Dr Ed Hutchinson, Senior Lecturer, MRC-University of Glasgow Centre for Virus Research (MRC CVR), said:
“This report is a reminder that, as well as having a serious impact on humans, influenza viruses infect many other species of birds and mammals. A great variety of influenza viruses infect wild animals, often without causing serious illness. However, in recent years a highly pathogenic strain of H5N1 influenza virus has been spreading around the world, causing serious illnesses in birds and occasionally infecting mammals. Influenza viruses are particularly common in waterfowl and shorebirds, which can carry the viruses long distances as they migrate. Although the Antarctic is extremely remote, it was inevitable that eventually the highly pathogenic H5N1 strain of influenza would reach the region, and infected birds were first reported by the British Antarctic Survey a few months ago.
“The fact that this virus has now started infecting mammals in the region is, sadly, also not surprising – viruses are usually extremely picky about which animal they infect, but influenza viruses are unusually good at infecting new host species.
“Importantly, there is a difference between isolated infections of a new species and a virus spreading efficiently within that species. It requires a lot of changes for a bird virus to become a mammalian virus, and at the current time there is no sign that this H5N1 virus has changed from being a dangerous virus of birds to a virus that can spread easily within any mammal species.
“However, this appearance of a dangerous virus in both the birds and mammals of such a fragile ecosystem is very concerning. This report highlights that this dangerous strain of H5N1 influenza virus has now reached all parts of the world, and as well as monitoring its impact on wildlife, ongoing work will be needed to reduce as much as possible its impacts on farmed animals around the world, and to minimise the risk that in the future the virus could adapt to spreading in humans.”
Prof Diana Bell, Professor Conservation Biology, UEA, said:
“These important findings confirm the spread of HPAI H5N1 to sub-Antarctic locations and together with the recent report of the virus in a dead polar bear in the high Arctic highlights the widespread distribution among both mammalian species and geographically to fragile ecosystems already threatened by global warming.”
Declared interests
Dr Kathleen Steinhöfel: “No conflicts of interest to declare.”
Prof Rowland Kao: “I am funded along with the APHA in a large consortium grant funded by the BBSRC to study methods to understand and combat H5N1 in the UK; also I chair Defra’s science advisory council’s exotic and emergent diseases committee, leading an independent scientific report commissioned by Defra on the current H5N1 pandemic.”
Dr Alastair Ward: “Alastair Ward collaborates with the Animal and Plant Health Agency on the FluMAP and Flu:TrailMAP consortia, two research projects funded by UK Research and Innovation and Defra to investigate the ongoing H5N1 avian influenza panzootic.”
Dr Ed Hutchinson: “Ed Hutchinson has received honoraria for work in a steering group of the Centre for Open Science (Open Practices in Influenza Research; 2021-2022) and on an advisory board for Seqirus (2022). He has unpaid positions on the board of the European Scientific Working group on Influenza and other respiratory viruses (ESWI) and as a scientific adviser to PinPoint Medical. His research group is funded in part by the FluTrailMap consortium mentioned in the press release, but he was not involved in the work reported here.”
Prof Diana Bell: “None.”