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Scientists comment on the first human case of Avian flu detected in the UK, as announced by UKHSA.
Prof Ed Hutchinson, Senior Lecturer, MRC-University of Glasgow Centre for Virus Research (MRC CVR), said:
How likely is it that the virus has or will spread human-to-human from this case?
“Because viruses are closely adapted to particular host species, it’s really hard for a bird flu virus to infect a human. This is why, despite the very high levels of H5N1 currently infecting wild and farmed birds, human infections with this virus are extremely rare, and normally only occur in people who have close contact with birds. Onward human-to-human transmission of a bird virus is even harder, and is exceptionally uncommon. Nothing has been reported suggesting that onward spread of bird flu to other humans has happened here. Nonetheless, health protection agencies will monitor carefully for any signs of human-to-human transmission around any case like this, so if the virus did evolve to become better at growing in humans this would be spotted as soon as possible.
What could be done to prevent future cases of H5N1?
“In the UK, the most important measures at the moment aim to reduce as much as possible the number of infections of farmed birds by H5N1, particularly from wild birds, and to understand where the most precautions need to be taken. The control measures announced over the weekend and ongoing surveillance by UKHSA and the APHA aim to do this. These were in place even before this human case was detected. Given the scale of the outbreak in wild birds, these measures will reduce the ongoing risk to farmed birds but they cannot eliminate it.
How worried should we be about this? How does the risk of contracting bird flu differ between people working in close contact with birds versus the general public?
“At the moment, this case is not a huge cause for concern. Although the virus is a serious infection for birds and the control measures are important for UK poultry, most of us do not have close contact with either wild or farmed birds, so the chances of most people becoming infected by a bird are very low. Every measure should be taken to minimise the risk of infection for people who work with or keep poultry, and the control measures announced over the weekend will help to reduce this risk. It’s good to hear that the person affected is currently well and that antiviral drugs have been offered to other people who may have been exposed. There is currently no sign of wider spread of this virus among humans and we have good surveillance for detecting viruses like this in the UK. If wider spread did occur the fact that we already have some reserves of vaccines and antiviral drugs would give us opportunities to intervene.
Any other information should readers know about the situation?
“Within the UK, it’s worth reminding people not to handle dead birds (particularly waterfowl) and to try and prevent pets from scavenging bird carcasses, and also to avoid feeding pets raw meat from birds. Sightings of dead or sick birds can be reported at https://www.gov.uk/guidance/report-dead-wild-birds or on 03459 33 55 77. It’s also important to note that influenza viruses are killed quickly by heating, so there should be no risk to the public from properly-cooked eggs or poultry.
“This is the UK experience of a global outbreak of H5N1 in wild birds, and its effects are different in other parts of the world. In some regions the virus has become a major problem for mammals as well as birds. In South America H5N1 is causing devastating outbreaks in seals and sea-lions, while in the USA it has managed to adapt to dairy cattle and is being shed in their milk – something which has not yet happened in the UK. Different strains of the virus are also circulating in birds in different parts of the world, and it is possible that these strains might have different properties. In the USA and Canada there have been two recent cases of humans getting severely ill after catching H5N1 from birds, in one case sadly leading to the person’s death. This underscores the potential risks of H5N1 infections, but it is also worth nothing that the H5N1 viruses currently circulating in UK birds are from a different strain of the virus to the ones in North America. Because human infections are so rare, how likely each strains is to cause severe disease in humans is still unclear. As a backdrop to all of this, virologists are watching carefully for any sign that H5N1 influenza viruses might be adapting to grow better in humans. This would be an exceptionally unusual event, but to minimise the risk of future influenza pandemics it is crucial that situations like this are carefully monitored.”
Dr Natsuko Imai, Research Lead in Epidemics in Wellcome’s Infectious Disease team, said:
“While avian flu H5N1 is commonly transmitted between birds, humans can also become infected through contact with infected birds. However, so far, there have been no documented cases of human-to-human transmission. The case confirmed by UKHSA today is not the same strain as the one causing outbreaks in dairy cattle in the US, where there is concern that continued spread among mammals could lead to the virus evolving the ability to spread between humans. Effective response relies on collaboration and clear communication between human and animal health workers. Being prepared can save lives, and requires robust surveillance and prevention measures, such as good biosecurity on farms and contact tracing, especially in areas with close animal-human contact. Research into transmission patterns, and how viruses change to infect different species continues to inform these preparedness efforts and identify emerging threats before they become crises.”
Prof Sir Peter Horby, Professor of Emerging Infectious Diseases and Global Health, Centre of Tropical Medicine and Global Health, University of Oxford, said:
“Human cases of influenza A/H5N1 infection acquired from animals, usually poultry, are rare but not unexpected. Since 2003 more than 900 cases of human H5N1 infection have been reported to the World Health Organisation. Whilst close monitoring of the infected person and their close contacts is warranted, such infections are not a cause for alarm. We should only become worried if there is evidence of onward transmission from person-to-person, which might indicate the virus has adapted to humans. In all the human H5N1 infections detected to date there has been no evidence of meaningful person-to-person transmission.
“The primary way to reduce the risk of all animal influenza viruses to humans is to control the spread of these viruses in poultry and livestock and to invest in developing diagnostic tests, vaccines, and drugs. It is sadly likely that at some point in future there will be an influenza pandemic, even if it’s not this virus.”
Prof Jonathan Ball, Deputy Vice-Chancellor, Liverpool School of Tropical Medicine; and Professor of Molecular Virology, Liverpool School of Tropical Medicine (LSTM), said:
“Avian H5N1 influenza, or ‘bird flu’, which as the name suggests circulates widely in wild birds, thankfully doesn’t transmit to humans very easily, and only really occurs in people who have regular contact with either wild birds or poultry. Even in the rare cases where people do become infected, onward human to human transmission is very unlikely.
“However, that doesn’t mean we can be complacent. There is always the risk that the virus can evolve and become better adapted to spread amongst humans, so it’s important to be vigilant, to ensure good wild fowl and poultry surveillance and when human cases do occur, to isolate the patient to remove the risk of onward transmission.
Dr Alastair Ward, Associate Professor of Biodiversity and Ecosystem; Programme Lead for Zoology, University of Leeds, said:
What could be done to prevent future cases of H5N1?
“Adherence to biosecurity best practice, including the use of PPE and disinfection when handing poultry or material that may have been contaminated by them, may limit transmission of H5N1 from infected poultry to humans. Reporting of symptoms observed within a poultry flock to the Animal and Plant Health Agency, and subsequent statutory testing and control measures are critical for preventing further spread among birds, as they have been in this case.
How worried should we be about this? How does the risk of contracting bird flu differ between people working in close contact with birds versus the general public?
“The UKHSA and APHA have avian influenzas under ongoing surveillance. We know what the genetic changes are that make the viruses more likely to jump to humans and to transmit between humans, and they have not been detected in the UK. Risks to the general public likely remain very low. Risks to people who work in close contact with birds, particularly ducks, geese, swans, chickens and turkeys are greater, but can be reduced by implementing biosecurity best-practice, including use of PPE and disinfection when making contact with birds or material that has been contaminated by them.
Professor Wendy Barclay FMedSci, Regius Professor of Infectious Disease at Imperial College London, said:
“Since the number of cases of H5N1 in poultry premises has increased again this winter, this is not unexpected.
“It’s important to remember that bird flu does not transmit readily between people without several simultaneous adaptive mutations in different genes.
“Genetic sequencing would confirm if this has happened, but with just one individual case, it is highly unlikely.”
Declared interests
Prof Ed Hutchinson “I have 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). I have 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. My group receives funding from the Wellcome Trust and from UKRI, including from the FluTrailMAP(One Health) consortium which aims to respond to H5N1 in mammals.”
Dr Natsuko Imai None
Prof Sir Peter Horby “I receive philanthropic funding from FluLab for a clinical trial of treatments for patients hospitalised with infleunza.”
Prof Johnathan Ball: None
Dr Alastair Ward I am a member of the FluMAP and Flu:TrailMAP consortia: multi-disciplinary groups of scientists funded by UKRI and Defra to better understand the ongoing H5N1 panzootic and how to better control it.
Prof Andrew Preston I have received research funding from several companies that make vaccines, but not for any work related to influenza.
For all other experts, no reply to our request for DOIs was received.