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Scientists comment on news from UKHSA that an invasive mosquito species (Aedes aegypti) has been detected in east London
Professor Heather Ferguson, Professor of Infectious Disease Ecology, University of Glasgow, and lead of the Mosquito Scotland project, said:
How significant is this news that this species has been detected in the UK?
“This finding is significant. The Aedes aegypti mosquito is primarily responsible for the transmission of many diseases mosquito-borne diseases, including Dengue, Zika and Chikungunya viruses. This mosquito is primarily found in the tropics, which is where the greatest public health burden of these diseases fall. Climatic conditions in the UK, including where it was found in London, are currently not likely to be suitable for these diseases to spread – however this could change in in coming years with warming temperatures. To make sure these diseases do not pose a risk to the UK public in the future, it is important that this mosquito species does not establish in the UK. In addition to their role in spreading diseases under the right environmental conditions, it can also cause a lot of nuisance biting. This is definitely something we do not want to get a foot hold in the UK
How are invasive mosquitoes monitored and tracked in the UK?
“Invasive mosquitoes in the UK are tracked in a number of different ways. First of all, the UK Health Security Agency carries out an active programme of monitoring at potential entry points in the UK – including at airports and ports, and near major transport routes commonly used by vehicles, including goods trucks coming from mainland Europe. At present, many of these monitoring sites are based in England – which makes sense given the proximity to transport routes to mainland Europe – but other parts of the UK can also be monitored. Additionally, invasive mosquitoes are monitored through the UK Health Security’s Mosquito Reporting Scheme – through which members of the public can ‘report’ when they see or get bitten by mosquitoes. Here people can also submit photos of the mosquito, or send the specimen in to the programme for identification (https://www.gov.uk/government/publications/mosquito-surveillance/mosquito-nationwide-surveillance) . Through our ‘Mosquito Scotland” project, we have also established a citizen reporting platforms where people in Scotland can report mosquitoes (https://www.mosquito-scotland.com/). We collaborate with UKHSA on this project, so should any invasive mosquito be reported in Scotland through this platform, we can quickly inform national authorities in the UK and Scottish government. ‘Citizen science’ reporting systems have been extremely effective for early detection of invasive mosquitoes in a number of European countries. Also, this was also how this recent detection of Ae. Aegypti in London was found – a member of the public reported it through the mosquito reporting scheme, allowing UKHSA to rapidly follow up. Members of the public are very much our key partners for mosquito surveillance – their input is so valuable.
What is the risk of infection of zika, chikungunya or dengue to individuals in the UK/ east London?
“This risk of being infected by any of these diseases in the UK/East London at present remains very low. Despite the warm conditions over the summer, it would require a very large number of these mosquitoes and sustained warm temperatures over a long period for these viruses to be efficiently transmitted. Additionally these mosquitoes would first need to bite people who had these diseases, which would have to have been acquired outside of the UK, to start off the transmission cycle. It is not impossible for people to be infected with these diseases overseas and carry with them on their return – numerous imported Dengue cases are reported in the UK every year – the chance of these people being bitten by a temporarily-present invasive mosquito, at the right time, and under the right environmental conditions, to start a transmission cycle is very low. While the recent reports of Ae aegypti biting people in London is a concern, this remains a somewhat isolated incident with not very many mosquitoes. Most likely this mosquito has not become established. Until that happens, the risk is low.
What would you say to someone who’s recently been bitten by a mosquito and may be worried?
“I would encourage members of the public not panic if they get a mosquito bite. It may be an annoyance, and lead to some short-term irritation just like when you get a mosquito bite on holiday. However at present, the risk of getting a tropical disease from a mosquito bite in the UK is extremely low. People should also keep in mind that not all mosquitoes are ‘invasive’, or a source of disease. We have at least 20 different mosquito species that are native to the UK, that can be found as far north as Shetland. These mosquitoes have been in the UK for longer than people have, and are a natural part of our ecosystems.
Should we expect more imports/ evidence of breeding in the UK with a warming UK climate?
“We do need to prepare and continue to monitor for the arrival of invasive mosquito species – given that climate change will likely increase the likelihood of their arrival in the UK, and the risk that once they do establish in the UK they may be able to spread diseases . It is a very positive step that the UK government already conducts mosquito surveillance. As the risk of arrival grows, we must make to sure to continue and further invest in these activities to make sure we can protect people in the UK from future risks.”
Dr David Weetman, Reader in Vector Biology, Liverpool of Tropical Medicine, said:
How significant is this news that this species has been detected in the UK?
“It is definitely important and raises the profile of what may become a more significant risk in the future as the climate continues to warm, though the risk associated with this particular detection seems low. Members of the public need to be more aware of the risks in order to stay as safe as possible.
How are invasive mosquitoes monitored and tracked in the UK?
“There are both citizen science reporting schemes and professional monitoring. The latter has typically been more successful and is based at airports, ports and road transport hubs or vehicle stopping places like service stations where vehicles that have crossed from the continent may stop. This has in the past led to detections of both the main threat species of Aedes mosquitoes (Aedes aegypti and Aedes albopictus), albeit infrequently. However it is really encouraging that this report of Aedes aegypti was – for the first time – made through the Mosquito Watch surveillance scheme by members of the public.
What is the risk of infection of zika, chikungunya or dengue to individuals in the UK/ east London?
“Although we do not know the source of these mosquitoes at the moment, it seems much more likely that they may have hitch-hiked with returning travellers from the tropics, noting that there are only a couple of places in the Eastern part of Europe where populations have established. To our knowledge there is not a significant reservoir of any of these diseases in human populations outside of southern Europe, with Italy and coastal southern France the worst impacted, mainly by chikungunya. Only a tiny proportion of mosquitoes are infected with these viral diseases so the statistical probability of one of the very few found carrying an infective viral dose is very, very low indeed.
What would you say to someone who’s recently been bitten by a mosquito and may be worried?
“Both Aedes aegypti and Aedes albopictus are aggressive biters which will readily feed on blood from humans (the females only; males only feed on sugar sources). However they are very distinctive in colouration – with dark brown to black body colour, white patterning and striped legs. None of the other 30 or so native UK mosquitoes resemble them and the most common human man biter is a much larger mosquito called Culiseta (this is approximately more than twice the size of Aedes mosquitoes and has a more drab appearance). Nevertheless if a reaction to a bite persists or a person feels unwell they should seek medical attention.
Should we expect more imports/ evidence of breeding in the UK with a warming UK climate? Again, how concerning would this be?
“Unfortunately – for imports – this is definitely a possibility because of the spread of Aedes albopictus across Europe in the past decades; this is the main threat to the UK because, whilst both Aedes species have eggs that can withstand months of drying, albopictus has eggs which can also be quite cold tolerant, caused by a recent mutation thought to have helped facilitate their spread from the native Asian range. This does not apply solely to mosquitoes. Other species which can carry disease, such as ticks – which can transmit Lyme disease, and if left untreated can produce long term chronic fatigue syndrome-type symptoms. Ticks don’t fly but are also possible hitchhikers back with travellers, presumably carried in luggage. Whilst the chance of establishment in locally breeding populations carrying disease in the UK for invasive mosquitoes species remains fairly low at present, a warming climate is very likely to increase risk.
Any other comments you think it would be useful for journalists/ the public to be aware of?
“It is really important that members of the public learn to recognise invasive species of mosquitoes in particular, but also to check their luggage carefully when returning from areas where the Aedes species are present. If in any doubt, try to capture if possible, take a picture and send asap to the UKHSA Mosquito Watch surveillance website (https://www.gov.uk/guidance/mosquitoes-how-to-report) It is also a good idea when travelling to affected areas to pack more than one of the WHO-approved repellents containing DEET or the lesser known icaridin. If one does not seem to be working try switching. This, along with avoiding being outside and relatively still during the peak biting hours – usually early morning and early evening for Aedes – is the best defense. Long sleeved clothing can help but if in a hot climate most people will understandably not favour this. Be vigilant – doing so helps both individuals and their community.”
Prof Martin Hibberd, Professor of Emerging Infectious Disease at the London School of Hygiene & Tropical Medicine (LSHTM), said:
“FindingAedes aegypti breeding in London is a milestone event as the UK’s rising temperatures drive an increasing risk of contracting zika, chikungunya or dengue infections from their blood meal bites.
“While the current mosquitos are unlikely to be infected, and so the risk to people will be low, their presence may indicate a regular summer event in future years. These mosquitos will not survive the cooler weather of Autumn or Winter, but new introductions next year may lead to breeding again.
“In other parts of the world where this happens, small disease outbreaks can occur if an infected human traveller, perhaps as a result of their journey to a country where these diseases are endemic, is bitten at home by one of these local mosquitos, infecting them. A chain of transmission, from mosquito to human to mosquito, can then be established, with potential disease outcomes, during the summer months.
“These mosquitos live in and around human habitations, and are perfectly adapted to city life, all they need is the right climate conditions, which the UK is now more regularly experiencing. Mosquito detection and eradication programs now need to be activated, to ensure that this does not become a bigger risk.”
Dr Steven White, Theoretical Ecologist, Population Ecology, UK Centre for Ecology & Hydrology (UKCEH), said:
“How significant is this news that this species has been detected in the UK?
“Aedes aegypti is the primary mosquito species for the transmission of global cases of dengue, chikungunya and Zika virus, all of which can cause significant human health risks. Although the risk to the UK human population remains low, this finding is indeed significant as it is the first time that this invasive species has been found breeding in the UK. However, this mosquito species is unlikely to establish in the near future since it is mainly a tropical species, preferring warmer weather than we have in the UK and therefore unlikely to spread beyond the finding by the UKHSA team.
How are invasive mosquitoes monitored and tracked in the UK?
“The UKHSA has a nationwide monitoring system for surveying the arrival of invasive mosquito species https://www.gov.uk/guidance/invasive-mosquito-surveillance. The mosquito traps are positioned in high-risk entry sites across the UK, including southeast England and London. If found, the UKHSA work with local authorities to eradicate the invasive mosquitoes.
What is the risk of infection of zika, chikungunya or dengue to individuals in the UK/ east London?
“There is a very low risk.
What would you say to someone who’s recently been bitten by a mosquito and may be worried?
“If the person has been bitten by a mosquito in the UK, then there is currently a low risk of mosquito-borne infections. However, if the person has recently travelled abroad to endemic countries and are feeling unwell then seeking medical advice is advised.
Should we expect more imports/ evidence of breeding in the UK with a warming UK climate? Again, how concerning would this be?
“Yes. Global movement of people and goods, combined with climate change, means that the UK is likely to experience introductions of invasive mosquitoes. One of the most worrying invasive mosquitoes is the related species the so called “tiger mosquito”, Aedes albopictus. This species is spreading throughout continental Europe and has caused recent novel outbreaks of dengue and chikungunya in European countries, such as France and Italy. This species is more cold-tolerant compared to the species found in London and is likely to try to establish in the UK in the near future. This species has already established on the other side of the English Channel.”
Dr César López-Camacho, Jenner Investigator at the Jenner Institute, Nuffield Department of Medicine, University of Oxford, said:
How significant is this news that this species has been detected in the UK?
“This is an important finding, particularly because this is the first confirmed evidence of Aedes aegypti breeding in the UK. However, it is important to distinguish the presence of the mosquito from the presence of the viruses it can transmit.
Aedes aegypti is one of the principal vectors of dengue, chikungunya and Zika, and other viruses globally, so evidence that it has been able to reproduce in the UK deserves attention. At the same time, there is currently no evidence that these mosquitoes have transmitted infection to humans, and UKHSA assesses the current risk to the public as very low.
From an arbovirus perspective, I would see this as an early warning rather than an immediate public-health threat. The significance is that one of the components necessary for transmission has temporarily been demonstrated here. For an outbreak to occur, the virus also needs to be introduced, usually through an infected traveller, and environmental conditions must allow mosquitoes to survive long enough for the virus to replicate and be transmitted onwards.
We therefore should not be alarmist, but neither should we regard mosquito-borne viruses as exclusively tropical diseases. The epidemiology of arboviruses in Europe is changing.
What is the risk of Zika, chikungunya or dengue infection to individuals in the UK or east London?
“For someone living in east London today, the risk of acquiring dengue, chikungunya or Zika from a mosquito bite remains very low. There is no evidence from this finding that any of these viruses are currently being transmitted locally.
“To generate local transmission you need several factors to coincide. You need a competent mosquito, an infected person who introduces the virus into the area, suitable temperatures for the virus to replicate inside that mosquito, and subsequent contact between that mosquito and another person.
“International mobility is therefore extremely relevant. London has a very large and highly mobile population, with substantial numbers of residents and tourists travelling between the UK and regions where these viruses circulate. A viraemic traveller can introduce a virus, while mosquitoes themselves can also be accidentally transported in baggage, vehicles or goods.
“We know that this process is no longer hypothetical in Europe. As of 26 August 2026, France had reported locally acquired chikungunya and dengue cases, for example. This demonstrates that, when competent mosquitoes, imported infections and favourable environmental conditions coincide, local transmission of these viruses can occur in Europe.
What would you say to someone who has recently been bitten by a mosquito and may be worried?
“I would reassure them. A mosquito bite in London does not mean that someone has been exposed to dengue, chikungunya or Zika.
“The current risk remains very low and there is no evidence of local transmission associated with this detection. For most people, a mosquito bite in the UK will simply result in the usual local reaction such as itching, redness or mild swelling.
“The situation is different if somebody develops fever or becomes unwell and has recently travelled to an area where dengue, chikungunya or Zika is circulating. In that situation, they should seek medical advice and make sure they mention their travel history.
“So, at present, recent international travel to an affected area is much more relevant clinically than simply having been bitten by a mosquito in London.”
Should we expect more introductions or evidence of breeding in the UK as the climate warms? How concerning is this?
“I think we should expect further introductions, and probably further instances where invasive mosquitoes survive long enough to reproduce. UKHSA itself has indicated that, in a warming climate, further incursions and increased survival of invasive mosquitoes in the UK are expected.
“The timing of this detection is particularly interesting because the UK has just experienced its provisionally hottest summer on record.
“Temperature is extremely important for arbovirus transmission. Warmer conditions can accelerate mosquito development, extend the period in which mosquitoes remain active and, critically, increase the rate at which viruses such as dengue or chikungunya replicate within a competent mosquito.
“Water availability and local humidity also influence mosquito survival and reproduction. Aedes aegypti is particularly well adapted to human environments and can breed in very small collections of standing water. What matters is therefore not simply national rainfall, but whether warm, sheltered local environments provide suitable breeding conditions.
“At present, the normal UK winter remains a major barrier to permanent establishment of Aedes aegypti. So finding breeding mosquitoes does not mean that the species is now established here.
“The concern is more about trajectory. With warmer summers, potentially milder winters, increasing international mobility and repeated opportunities for mosquitoes to be introduced, the ecological window for these vectors to survive is becoming wider.”
Any other comments that would be useful for journalists or the public?
“One important point is that we are better prepared against some of these diseases than we were a decade ago.
“Vaccines against dengue and chikungunya are now licensed, although their use depends on the individual, their destination and the specific vaccine recommendations. There is currently no licensed vaccine against Zika.
“My own research has focused for many years on developing vaccines against arboviruses, including dengue, chikungunya and Zika. Some of our vaccine work at the Jenner Institute has progressed from preclinical development into Phase I clinical evaluation in the UK, and more recently we have been developing mRNA vaccines against dengue and chikungunya.
“From a vaccine-development perspective, this type of event reinforces why preparedness matters. We do not want to begin developing vaccines only after a pathogen or its vector has become established.
“mRNA platforms are particularly interesting for emerging infections because they allow vaccine candidates to be designed and adapted relatively rapidly once the relevant antigen has been identified. That adaptability could become increasingly valuable as the geographical distribution of arboviruses changes.
“However, vaccines are only one part of preparedness. The broader lesson from dengue, chikungunya and Zika is that surveillance, rapid diagnosis, vector control and vaccine development have to work together.
“The message to the public should therefore be proportionate: there is no evidence of local transmission of dengue, chikungunya or Zika in east London and the immediate risk remains very low. But from an infectious-disease perspective, the finding is important because it shows that the ecological conditions affecting mosquito-borne diseases in Europe, including the UK, are changing.”
Prof Amanda Callaghan, Professor of Invertebrate Zoology and Curator of the Cole Museum of Zoology, University of Reading, said:
“This is a new record of this species breeding in the UK, something that was likely given a few recent discoveries of this species in the country. Invasive mosquitoes enter the country via many routes, including air travel, but they tend not to survive our winter conditions.
“They are generally not a health issue for the general public and there is no reason to be concerned at present, although climate change could mean that we need to be vigilant in the future. Luckily, the UKHSA closely monitors mosquitoes in the UK and are well equipped to deal with incursions.”
Prof Trudie Lang, Professor of Global Health Research, University of Oxford, said:
“It is concerning that Aedes aegypti has been identified breeding in east London. This is a species of major global health significance and, although its presence in the UK remains very rare, its detection and evidence of local breeding are important from a public-health and surveillance perspective.
“This finding also needs to be considered in the wider European context. We have seen an increasing number of locally acquired mosquito-borne infections across parts of Europe, including locally acquired chikungunya cases in France this summer. These diseases are usually limited to and associated with significant health impacts in tropical and subtropical regions, but that geographical distinction is becoming less clear.
“UKHSA and other agencies will now be working to establish whether the mosquitoes identified in London are carrying any pathogens. Based on the information available so far, there does not appear to be evidence of human transmission or that these mosquitoes are infected, and therefore the immediate risk to the public remains very low. It is important, however, that awareness, surveillance and laboratory testing continue.
“From a global-health perspective, this is also a timely reminder of the changing epidemiology of mosquito-borne diseases. Climate change, warmer temperatures and changes in rainfall can create more favourable conditions for mosquitoes to survive and reproduce, while increasing international travel and the movement of mosquitoes and other vectors can introduce species into new environments.
“The concern is not simply the presence of a particular mosquito species, but the combination of a competent vector, suitable environmental conditions and the introduction of a pathogen together. Diseases such as chikungunya, dengue and Zika therefore warrant continued surveillance as the climate and distribution of mosquito vectors change.
“The UK has strong public-health and laboratory surveillance capabilities, and this detection provides an opportunity to ensure those systems remain sufficiently sensitive to identify both invasive mosquito populations and any pathogens they may carry at the earliest stage. In the UK we should also be taking every effort to learn scientifically when these event happen so we can learn from these.”
Prof Tom Solomon CBE, Director of The Pandemic Institute in Liverpool, said:
How significant is this news?
“This is an important finding because it is the first evidence of Aedes aegypti breeding in the UK. However, detecting the mosquito is not the same as detecting the diseases it can carry. There is no evidence of locally acquired dengue, chikungunya or Zika, and the current risk to the public is very low. In Liverpool we have studied mosquito-borne viruses for many years, including our own work on Zika, chikungunya and dengue. What this research shows is that several things must come together before local transmission can occur: the right mosquito, a virus introduced by an infected traveller, suitable temperatures and opportunities for onward transmission.”
How are invasive mosquitoes monitored and tracked?
“UKHSA undertakes active surveillance using mosquito traps and works with local authorities and other partners to identify invasive species. This is complemented by Mosquito Watch, through which members of the public can submit photographs or specimens. In Liverpool researchers have also tested whether native British mosquitoes are capable of transmitting viruses such as dengue and chikungunya, and have studied how temperature affects the relationship between mosquitoes and the viruses they carry. Laboratory research, field surveillance and reports from the public all contribute different pieces of the early-warning system.
What is the risk of Zika, chikungunya or dengue in the UK or east London?
“The immediate risk is extremely low. These mosquitoes do not somehow contain dengue, chikungunya or Zika simply because they belong to this species. A mosquito would first have to bite someone carrying the virus and then, after the virus had developed inside it, bite another person. There is no evidence that this has happened or that anyone has acquired one of these infections locally. Our Liverpool research on dengue has included its less common but potentially serious effects on the brain and nervous system. This underlines why good surveillance and preparedness are important, while also keeping the current finding in proportion.
What would you say to someone recently bitten by a mosquito?
“A mosquito bite in east London is overwhelmingly likely to be an irritating bite rather than a sign of dengue, chikungunya or Zika. Treat the itching in the usual way and try not to scratch it. If someone becomes significantly unwell, particularly with fever, rash, severe headache or confusion, they should seek medical advice and mention any recent overseas travel. Recent travel to a country where one of these viruses is circulating would be much more relevant than an uncomplicated mosquito bite in London.”
Should we expect more introductions or evidence of breeding as the UK climate warms?
“Yes. We should expect more invasive mosquitoes to arrive through international travel and trade, and warmer conditions may allow some to survive and breed for longer. At Liverpool we have modelled how climate change may alter the distribution of mosquito-borne and other vector-borne diseases. We have also assessed the ability of British mosquito species to transmit emerging viruses. Current work across Liverpool, including at Liverpool School of Tropical Medicine and through The Pandemic Institute, is strengthening dengue risk prediction and preparedness. However, climate change does not mean that widespread transmission in the UK is inevitable. Aedes aegypti is not established here, and the typical UK climate, particularly our winters, remains a substantial barrier to its long-term survival. This is a warning to remain vigilant and invest in surveillance, not a reason for public alarm.”
Any other useful comments?
“The rapid identification of the mosquitoes and larvae, followed by control measures and enhanced surveillance, shows the public-health system working as it should. People can help by emptying standing water from buckets, plant pots, paddling pools, blocked drains and other containers. They can also report unusual mosquitoes through UKHSA’s Mosquito Watch scheme.”
https://ukhsa-newsroom.prgloo.com/news/invasive-mosquito-species-detected-in-east-london
Declared interests
Dr David Weetman: I lead a large UK-NIHR project in West Africa, which tests products provided by manufacturers for possible Aedes control but none are likely to be used in the UK at present to my knowledge. The phone app MosquitoAlert which is quite widely used in continental Europe is also part of the project but is not a commercial company.
Prof Martin Hibberd: I have received funding from international governments, pharmaceutical companies and donations that support my work to understand zika, chikungunya or dengue disease, the viral transmission chains and their prevention.
Dr Steven White: I don’t have links to industry – I am an academic and only receive public funding.
Dr César López-Camacho:
Dr César López-Camacho is a Jenner Investigator at the Jenner Institute, Nuffield Department of Medicine, University of Oxford, where he leads research on vaccines against arboviruses, particularly mosquito- and tick-borne viruses, and leads work on mRNA vaccine technology.
Competing interests: Dr López-Camacho develops vaccines against arboviruses, including dengue, chikungunya and others, using viral-vector and mRNA platforms. Some of this work has progressed from preclinical development to Phase I clinical evaluation in the UK. He has no competing financial interest related to the current detection of Aedes aegypti in the UK.
Prof Trudie Lang: “No conflict”
Prof Amanda Callaghan: “Prof Amanda Callaghan supervises a PhD student who was part of the UKHSA study”
Prof Tom Solomon:
Member of the Encephalitis Society (a charity focused on encephalitis awareness, support and research) since 1998 and President of the Encephalitis Society since 2019.
Director of The Pandemic Institute (since September 2021), which has received funding from Innova, CSL Seqirus, Aviva and DAM Health (unpaid).
Advisor to the GSK Ebola Vaccine programme in 2015 and the Siemens Diagnostic Programme in 2018 and 2019 (paid).
Part of the Data Safety Monitoring Committee of the GSK Study to Evaluate the Safety and Immunogenicity of a Candidate Ebola Vaccine in Children GSK3390107A (ChAd3 EBO-Z) vaccine (unpaid).
Chaired the Siemens Healthineers Clinical Advisory Board in 2018 and again in 2019 (paid).
Co-Chaired the World Health Organization Covid Neuro Coalition task force in 2020 (unpaid) and sat on the United Kingdom of Great Britain and Northern Ireland Government’s Advisory Committee on Dangerous Pathogens (ACDP) between 2019 and 2023 (unpaid), and the Medicines and Healthcare products Regulatory Agency (MHRA) Expert Working Group on COVID-19 vaccines between 2020 and 2023 (paid).
Advised the United Kingdom COVID-19 Therapeutics Advisory Panel (UK-CTAP) between 2020 and 2021 (unpaid).
Member, COVID-19 Vaccines Benefit Risk Expert Working Group, for the Commission on Human Medicines (CHM) committee of the MHRA between 2020 and 2023 (paid).
Committee Member of the Wellcome Trust Pathogen Biology and Disease Transmission Discovery Advisory Group (paid).
For all other experts, no reply to our request for DOIs was received.