Vector Borne Disease Statistics in UK 2026 | Cases, Mosquitoes, Ticks & Key Facts

Vector-Borne Disease in the UK 2026

Vector-borne diseases — illnesses transmitted to humans by organisms such as ticks and mosquitoes — are becoming a steadily more prominent part of the UK’s public health landscape as climate change alters conditions for the insects and arachnids that carry them. On May 21, 2026, the UK Health Security Agency (UKHSA), working alongside the Department for Environment, Food and Rural Affairs (Defra) and the Animal and Plant Health Agency (APHA), published its first-ever annual One Health Vector-Borne Disease Surveillance report, bringing together human, animal, and vector data from across 2025 into a single comprehensive national picture for the first time. The report confirmed that Lyme disease remains the most common locally acquired vector-borne infection in England, with 1,168 laboratory-confirmed acute cases in 2025 — a notable rise from 959 cases in 2024.

This report compiles the latest verified UK government data — sourced directly from UKHSA, Defra, APHA, and the UK government’s official Tick Surveillance Scheme — covering tick-borne infections, mosquito-borne disease detections, imported travel-associated cases, and the invasive species UKHSA is actively monitoring as of this week. As of today, an important update from UKHSA’s climate-risk research is worth noting: the agency has explicitly warned that the risk of vector-borne disease in the UK is increasing as the climate changes, with warmer, wetter conditions extending tick activity periods and enabling disease-carrying mosquito species to survive on British soil for longer stretches of the year than in the past.

Interesting Vector-Borne Disease Facts and Latest Statistics in the UK 2026

Data source: UK Health Security Agency; Defra; Animal and Plant Health Agency; UKHSA/APHA First Annual One Health Vector-Borne Disease Surveillance Report, May 2026

These figures confirm that vector-borne disease risk in the UK is a genuine and growing public health concern rather than a distant or theoretical one. UKHSA’s first joint One Health surveillance report found 1,168 laboratory-confirmed acute Lyme disease cases in England during 2025, a rise of more than 20% from the 959 cases recorded in 2024, cementing Lyme disease’s position as the country’s most common locally acquired vector-borne infection. UK research has separately found that, on average, 5.8% of ticks tested nationally carry the bacteria responsible for Lyme disease, though this figure varies considerably by region and season, and government scientists caution it should be read as a national average rather than a uniform risk across the country.

Beyond ticks, the same UKHSA report documented two probable cases of tick-borne encephalitis (TBE) complex in 2025, neither of which involved international travel, bringing the total number of locally acquired TBE-complex cases in the UK since the virus was first identified in 2019 to six. On the mosquito side, imported infections continue to dominate the picture: imported malaria cases hit 2,106 in 2023, the highest total in 20 years, while imported dengue cases reached an all-time record of 904 in 2024 before falling back substantially in 2025 — trends explored in detail throughout this report.

UK Lyme Disease and Tick-Borne Infection Statistics in 2026

2024 Confirmed Cases......... 959   ████████████████████████
2025 Confirmed Cases......... 1,168 ██████████████████████████████
Average % of Ticks Carrying Lyme Bacteria... 5.8%

Data source: UKHSA and Defra/APHA, First Annual One Health Vector-Borne Disease Surveillance Report, May 21, 2026; UKHSA Tick Surveillance Scheme dashboard

UKHSA’s Tick Surveillance Scheme, established in 2005, is the UK government’s primary tool for mapping and monitoring tick distribution nationwide, and it forms the backbone of the data behind this year’s landmark One Health surveillance report. The scheme identifies Ixodes ricinus, commonly known as the sheep or deer tick, as the species of greatest public health concern in the UK, since it is both the most likely tick species to bite humans and the primary vector for Lyme disease as well as other tick-borne infections circulating in the country. The rise from 959 confirmed Lyme disease cases in 2024 to 1,168 in 2025 represents one of the more significant year-on-year increases UKHSA has recorded, and the agency links this pattern to warmer, wetter conditions that extend the seasonal window during which ticks are active and questing for hosts.

The two probable cases of tick-borne encephalitis (TBE) complex identified in 2025 are notable because neither patient had a history of recent international travel, meaning UKHSA classifies them as locally acquired infections. Since TBE complex diagnoses cannot always be distinguished in the laboratory from the closely related louping ill virus (LIV), which has circulated in UK sheep populations for decades, these cases are reported jointly as “TBE complex.” With six such locally acquired cases confirmed since the virus was first identified circulating in UK ticks in 2019, TBE remains rare in absolute terms, but UKHSA’s decision to track and publicly report every case reflects the seriousness with which the agency treats any sign of an established, non-imported vector-borne pathogen taking hold on British soil.

UK Mosquito-Borne Virus Detection Statistics in 2026

West Nile Virus — First UK Detection..............2023 (fragments, Nottinghamshire mosquitoes)
Usutu Virus — First UK Detection (Blackbirds).... 2020
Usutu Virus — Circulating in South-East England.. ~6 years
Confirmed Human Cases of Either Virus in UK....... 0

Data source: UKHSA and Defra/APHA, First Annual One Health Vector-Borne Disease Surveillance Report, May 21, 2026; UKHSA blog, “How we protect the UK from vector-borne diseases”

While the UK’s Lyme disease trend has drawn significant attention, government surveillance of mosquito-borne viruses tells a more cautious but still evolving story. West Nile virus was detected for the first time in UK mosquitoes in samples collected in 2023, when fragments of the virus were identified in Aedes vexans mosquitoes collected from wetlands in Nottinghamshire. UKHSA has been explicit that this detection reflects the presence of the virus in the local mosquito population rather than any confirmed transmission to humans, and the agency currently rates the public health risk from West Nile virus in the UK as very low — a rating maintained specifically because ongoing surveillance has not detected further evidence of the virus circulating since the initial finding, nor any confirmed human cases.

Usutu virus, a closely related virus in the same family as West Nile, has a longer and more established presence in the UK, having been first detected in blackbirds in England in 2020. Government data now shows Usutu virus is considered endemic in mosquitoes and birds across south-east England, with evidence suggesting it has been circulating in the region for approximately six years, and the virus was detected in wild birds in Scotland for the first time in 2025, extending its known geographic range further north. Despite this established animal-and-mosquito circulation, UKHSA notes that Usutu virus rarely causes symptomatic disease in humans, and consequently no human cases have been recorded in the UK to date — a genuinely reassuring finding, even as the virus’s spread illustrates how mosquito-borne pathogens can become quietly established in the UK environment well before any direct human health impact becomes apparent.

UK Imported Malaria and Travel-Associated Infection Statistics in 2026

2019 (Pre-Pandemic).................1,719 cases  ██████████████████
2022................................1,555 cases  ████████████████
2023 (20-Year High).................2,106 cases  █████████████████████
2024............................... 1,812 cases  ███████████████████
2025............................... 1,629 cases  █████████████████

Data source: UK Health Security Agency, Annual Malaria Reports and Travel-Associated Infections Reports, 2023–2026

UKHSA confirmed that imported malaria cases in England, Wales, and Northern Ireland exceeded 2,000 for the first time in 20 years in 2023, reaching 2,106 confirmed cases following travel abroad — a 26% increase on the 1,555 cases recorded in 2022 — a rise the agency attributes to malaria’s global resurgence in several endemic countries combined with a substantial rebound in international travel following the removal of pandemic-era restrictions. Since that 20-year peak, imported case numbers have moderated somewhat, falling to 1,812 in 2024 and 1,629 in 2025, though UKHSA is careful to stress that malaria remains at “consistently high levels” among returning UK travellers rather than genuinely declining, with most cases concentrated during the late spring and summer travel months between May and October.

Malaria remains a potentially fatal but almost entirely preventable disease when travellers correctly follow prevention guidance, including taking prescribed antimalarial medication and using mosquito bite avoidance measures. UKHSA data shows six malaria-related deaths occurred in the UK in 2023, matching the annual average of six deaths recorded between 2014 and 2023 — a consistency that underscores both how serious untreated malaria can be and how stable the disease’s fatality rate has remained even as overall case numbers have fluctuated with global travel and disease patterns. UKHSA’s consistent messaging ahead of each travel season emphasises that anyone travelling to a malaria-endemic region, including those visiting friends and relatives abroad, should seek destination-specific travel health advice well in advance of departure, a pattern of behavioural risk that intersects closely with the UK’s broader travel and tourism trends detailed in the UK tourism statistics, given record levels of outbound travel by UK residents.

UK Imported Dengue and Chikungunya Statistics in 2026

Dengue Cases 2023.................. 634   █████████████
Dengue Cases 2024 (Record)......... 904   ██████████████████
Dengue Cases 2025 (Sharp Fall)..... 344   ███████
Chikungunya Cases 2023............. 45    █
Chikungunya Cases 2024............. 112   ██
Chikungunya Cases 2025 (14-Yr High). 160  ███

Data source: UK Health Security Agency, Travel-Associated Infections Reports, 2024–2026

UKHSA’s travel-associated infections surveillance shows that imported dengue cases in England, Wales, and Northern Ireland reached an all-time record of 904 in 2024, up from 634 in 2023, before falling dramatically to just 344 cases in 2025 — most linked to travel to India, Thailand, and Indonesia. UKHSA describes this decline as part of a broader global reduction in dengue transmission during 2025, rather than a change specific to UK travellers, and continues to monitor the situation closely given how sharply dengue numbers can swing from year to year in line with outbreak activity in the destination countries where UK travellers most frequently pick up the infection.

While dengue eased in 2025, chikungunya moved firmly in the opposite direction, with 160 imported cases reported in 2025 — the highest annual total recorded since 2014, representing a 43% increase on the 112 cases seen in 2024, which was itself more than double the 45 cases recorded in 2023. Most chikungunya infections were linked to travel in Southern Asia. UKHSA’s 2025 report also documented a genuine first: three cases of Oropouche virus disease, all linked to travel to Brazil, marking the first time this emerging arbovirus has been reported in returning travellers to England, Wales, and Northern Ireland. Alongside these, seven Zika virus cases were confirmed in 2025, while no cases of Japanese encephalitis or yellow fever were reported, rounding out a travel-associated infection picture that UKHSA says highlights the need for clinicians to broaden pre-travel health assessments beyond malaria alone to cover this expanding range of arboviral threats.

UK Invasive Species and Vector Ecology Statistics in 2026

Yellow-Legged Hornet Nests, 2023.................. 72   ████████████
Yellow-Legged Hornet Nests, 2024.................. 24   ████
Yellow-Legged Hornet Nests, 2025 (Cumulative)..... 163+ █████████████████████████
Confirmed 2nd-Generation UK-Bred Hornets (2025).... 4   █

Data source: Animal and Plant Health Agency, National Bee Unit, Yellow-Legged Hornet Rolling Updates, 2023–2026

While not a direct disease vector to humans, the yellow-legged hornet, commonly known as the Asian hornet, is tracked closely by APHA’s National Bee Unit as part of the UK’s broader invasive-species and ecological surveillance effort, since its expansion illustrates the same climate-driven range-shift dynamics affecting disease-carrying ticks and mosquitoes. First detected in the UK in Tetbury in 2016, the species has produced increasingly frequent incursions since, with 2023 standing out as an unprecedented year with 72 nests found and destroyed, before activity fell to 24 nests in 2024. By contrast, APHA data through 2025 recorded more than 163 nests found and destroyed for the year, alongside genuinely concerning evidence that the species may be establishing a foothold: four spring-caught queens in 2025 were confirmed as second-generation offspring of nests destroyed the previous autumn, in Coldred and Udimore, representing the first evidence of a second generation of yellow-legged hornets being produced in Great Britain.

APHA’s National Bee Unit emphasises that while these queen numbers remain very low in absolute terms, the confirmation of overwintering and successful local reproduction is a meaningful ecological signal, since it suggests the species may be capable of surviving UK winters under current climate conditions rather than relying entirely on fresh incursions from continental Europe each year. The government’s strategy centres on rapid nest destruction to prevent queens from dispersing and founding new colonies, and relies heavily on public reporting through the free Asian Hornet Watch app or an online sighting form, since early detection dramatically improves the odds of successfully eliminating a nest before it can produce new queens. This same pattern of climate-enabled range expansion — where warming UK conditions increasingly allow species that previously could not survive or reproduce locally to establish themselves — is the unifying ecological thread connecting the hornet’s spread to the tick and mosquito trends detailed throughout this report, a broader climate dynamic also explored in the UK cost of living statistics, where recent Middle East-driven energy volatility has been flagged by UK economic forecasters as one of several compounding pressures facing British households and public services this year.

UK Climate Change and Vector-Borne Disease Risk Statistics in 2026

Direct Water/Heat Link to Vector Activity........... Confirmed by UKHSA
Tick Active Season — Historically................... Spring-Autumn
Tick Active Season — 2026 Trend..................... Extending Longer
Mosquito Species With UK Disease-Transmission Potential Detected.. Multiple

Data source: UK Health Security Agency; London School of Hygiene & Tropical Medicine; UK Centre for Ecology & Hydrology

UKHSA has been explicit and consistent in its official guidance: the risk of vector-borne disease in the UK is increasing as the climate changes, with the agency warning that without decisive action, these shifts could substantially increase disease burden and put UK healthcare systems under new strain. This assessment is reinforced by the record-breaking May and June 2026 heatwaves that swept across England, which UKHSA and the Met Office jointly flagged as part of a wider pattern of increasingly severe and increasingly early-arriving extreme weather — conditions that simultaneously extend the active season for ticks and create more favourable breeding conditions for mosquitoes capable of transmitting disease, a connection explored in greater depth in the heat-related deaths statistics for the UK, which document the same underlying climate trends driving both direct heat mortality and the expanding range of disease-carrying vectors this year.

In direct response to this evolving risk, UK research institutions have accelerated their surveillance and modelling capacity throughout 2026. Researchers at the London School of Hygiene & Tropical Medicine established the first captive colony of a native British mosquito species in 2026 specifically to study its capacity to transmit emerging arboviruses under laboratory conditions, while a new £1.5 million One Health Vector-Borne Diseases Hub, funded jointly by Defra and UK Research and Innovation through the Biotechnology and Biological Sciences Research Council, now brings together Imperial College London, the Pirbright Institute, LSHTM, the University of Liverpool, and the UK Centre for Ecology & Hydrology to share vector-borne disease data across the UK research community and with policymakers, enabling faster responses to any future outbreak. Taken together, this expanding evidence base — from UKHSA’s first joint annual surveillance report to new dedicated research infrastructure — signals that vector-borne disease has moved firmly onto the UK’s mainstream public health agenda for 2026 and beyond.

Disclaimer: This research report is compiled from publicly available sources. While reasonable efforts have been made to ensure accuracy, no representation or warranty, express or implied, is given as to the completeness or reliability of the information. We accept no liability for any errors, omissions, losses, or damages of any kind arising from the use of this report.

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