Overview

Vector-borne and climate-sensitive diseases present a growing public health concern in the Highland region, with Lyme disease remaining the most significant current risk. Warmer temperatures and shifting precipitation patterns are likely to lengthen tick activity seasons and increase opportunities for human exposure, while future climatic conditions could create suitable environments for mosquito-borne diseases such as West Nile virus. Current management is largely centred on public awareness and clinical response to tick bites, with more limited proactive surveillance. Strengthened monitoring, better data integration and closer cross-sector collaboration could support earlier detection and more effective prevention. Without further action, climate-driven changes in vector ecology, wildlife hosts and human outdoor activity could amplify disease transmission potential across Highland communities.

 

What is the current level of risk?

Vector-borne diseases are infections caused by parasites, viruses, or bacteria that are transmitted to humans or animals through blood-feeding arthropods such as ticks, mosquitoes, midges, fleas and sandflies.[1] Climate-sensitive diseases are those whose transmission is strongly influenced by weather and climate, because temperature, rainfall, humidity and seasonal changes directly affect vector survival, development and biting rates, as well as the pathogens they carry.[2]

Vector-borne and climate-sensitive diseases pose a tangible, though spatially variable, risk to people in the Highland region. The most prominent concern is Lyme borreliosis, transmitted by castor bean ticks (Ixodes ricinus), whose distribution and seasonal activity have increased in northern and upland areas as milder winters and longer vegetation seasons create favourable tick habitats.[3],[4] Highland’s extensive deer populations, rough grassland, and mixed woodland provide ideal conditions for the tick–deer–small mammal cycle supporting Borrelia burgdorferi (one of the bacterial species that causes Lyme disease) transmission.[5] Recorded human cases of Lyme disease in Scotland have risen markedly over the past two decades, with Highland among the most affected regions.[6]

Tick-borne encephalitis virus, though not endemic, has been detected in ticks in parts of the UK.  It has the potential for northward expansion under warmer conditions.[7] Other potential climate-sensitive threats include midge- and mosquito-borne diseases such as West Nile virus and Usutu virus, for which competent vectors (i.e. mosquito or other species capable of acquiring, maintaining, and transmitting the pathogen) already exist in the UK.[8]

 

What is the future level of risk?

By the 2080s, risks to people in Highland from vector-borne and climate-sensitive diseases are expected to increase due to warmer temperatures, altered precipitation patterns, and changing ecosystems that favour vector survival and reproduction. Projected rises in average and seasonal temperatures could extend the active period of castor bean ticks (Ixodes ricinus) by several months each year, particularly at higher altitudes and northern latitudes where cold previously limited their survival.[9],[10] Longer vegetation seasons and reduced frost frequency will enhance larval and nymphal overwintering success, leading to increased tick abundance and, consequently, higher transmission potential for Lyme disease and possibly tick-borne encephalitis virus. Modelling studies indicate that castor bean ticks may expand further north and to higher elevations across Scotland under medium and high emission scenarios, implying that remote Highland areas could experience heightened exposure.[11]

For mosquito-borne diseases, although transmission risk currently remains low, warmer and wetter summers may improve breeding conditions for mosquitos, the principal bridge vectors for West Nile virus.[12] By 2100, modelled risk for West Nile virus increases substantially in southern Britain, but sporadic incursions could occur further north during anomalously warm summers, particularly where wetland habitats support mosquito populations.[13] By the end of the century, parts of north-west Scotland including areas within the Highland region could experience improved suitability for West Nile virus host species. This northward shift in ecological suitability reflects the potential emergence of conditions favourable for novel mosquito–bird transmission cycles, warranting continued monitoring and preparedness measures.[14],[15]

 

 

Is the risk being managed or adapted to?

Management of climate-sensitive and vector-borne disease risk in the Highland region remains limited but is supported by wider national surveillance and adaptation frameworks. The UK Health Security Agency (UKHSA) monitors key zoonotic infections, including Lyme diease, West Nile virus, and tick-borne encephalitis. Public Health Scotland and NHS Highland lead localised public health responses.[17],[18] In the Highland region, the principal adaptation activity is surveillance and awareness for Lyme disease, which is well-established across both medical and land management sectors.[19] This includes public information campaigns on tick avoidance, habitat management on recreation land, and improved diagnostic awareness among clinicians.[20]

For emerging mosquito-borne diseases, preparedness is primarily preventative, relying on national risk assessment and vector monitoring networks rather than active control measures.[21] The absence of routine mosquito surveillance specific to Highland habitats constrains early detection capacity. While the Scottish Government’s adaptation programmes recognise zoonotic disease as a priority health concern, actions have focused more on human and livestock disease response systems than on anticipatory environmental surveillance.[22] Consequently, the region’s current management approach can be characterised as reactive rather than preventive. This is sufficient for existing tick-related risk, but inadequate to address future threats from expanding mosquito and midge vectors under projected climatic change.

 

Are there benefits from further action in the next five years, over and above what is already planned?

There are potential benefits from strengthening for vector-borne and climate-sensitive diseases over the next five years. Current measures focus largely on Lyme disease, yet projected climatic shifts highlight the need for earlier and more coordinated responses to new and emerging vector threats. Expanding vector surveillance networks to include systematic mosquito and midge monitoring in wetland and coastal habitats would provide critical baseline data for assessing changing distribution patterns.[23] Enhanced monitoring could also support early warning systems that link climate and health intelligence, consistent with the adaptation priorities outlined in the third Scottish National Adaptation Plan 2024–2029.

Further benefits could arise from cross-sector collaboration between environmental health, forestry, tourism, and community organisations to reduce human exposure risks, particularly for outdoor workers and visitors to high-use recreational areas. Improved clinical training for early recognition of vector-borne infections and expanded public communication campaigns would strengthen community resilience.[24] Proactive investment now could safeguard public health and reduce longer-term healthcare and economic costs associated with future outbreaks, especially in remote rural communities with limited medical capacity.[25]

 

Cascading and Interacting Risks

Vector-borne and climate-sensitive diseases in Highland are closely interlinked with other climate risks affecting land use, ecosystems, and public health. Warming temperatures and wetter conditions that favour tick and mosquito proliferation also influence agricultural pests, wildlife populations, and habitat change, amplifying indirect exposure risks.[26] Increases in deer density, driven partly by milder winters and reduced mortality, can intensify local tick abundance and sustain the Lyme disease transmission cycle.[27] Similarly, wetter summers that promote mosquito breeding can coincide with flooding events, creating stagnant water habitats that further expand vector range.[28]

Socioeconomic and health system vulnerabilities compound these ecological interactions. Rural isolation and limited clinical capacity in the Highland region can delay diagnosis and treatment of vector-borne infections, particularly during concurrent health pressures such as heat stress or flooding-related displacement.[29] Changes in recreation and tourism patterns, such as longer outdoor seasons and growth in nature-based tourism, may increase human exposure in tick-prone landscapes. Disease risk does not operate in isolation but interacts dynamically with environmental, economic, and public health systems, creating potential feedback loops that heighten overall climate risk to Highland communities.

 

Options for regional collaboration

• Develop integrated climate–health data systems that connect meteorological, land-use, and public health datasets to improve early warning, forecasting, and risk communication for vector-borne diseases.
• Strengthen community and occupational awareness programmes for high-risk groups, such as outdoor workers, land managers, and recreation providers, ensuring consistent messaging on tick prevention, bite management, and disease symptoms.

References

[1] Centre for Climate and Health Security and UK Health Security Agency, UK Government, “Health Effects of Climate Change (HECC) Report,” December 19, 2024, https://www.gov.uk/guidance/health-effects-of-climate-change-hecc-report.

[2] Centre for Climate and Health Security and UK Health Security Agency, UK Government, “Health Effects of Climate Change (HECC) Report,” December 19, 2024, https://www.gov.uk/guidance/health-effects-of-climate-change-hecc-report.

[3] Lucy Gilbert, “The Impacts of Climate Change on Ticks and Tick-Borne Disease Risk,” Annual Review of Entomology 66, no. 1 (January 7, 2021): 373–88, https://doi.org/10.1146/annurev-ento-052720-094533.

[4] Arran J. Folly et al., “Emerging Threats to Animals in the United Kingdom by Arthropod-Borne Diseases,” Frontiers in Veterinary Science 7, no. 20 (February 4, 2020), https://doi.org/10.3389/fvets.2020.00020.

[5] Centre for Climate and Health Security and UK Health Security Agency, UK Government, “Health Effects of Climate Change (HECC) Report,” December 19, 2024, https://www.gov.uk/guidance/health-effects-of-climate-change-hecc-report.

[6] Dr. Katharine Dow, “Links between Climate Change and Health in Scotland” (The Scottish Parliament, July 22, 2025), https://www.parliament.scot/chamber-and-committees/research-prepared-for-parliament/research-briefings/2025/7/22/links-between-climate-change-and-health-in-scotland/pdf.

[7] Centre for Climate and Health Security and UK Health Security Agency, UK Government, “Health Effects of Climate Change (HECC) Report,” December 19, 2024, https://www.gov.uk/guidance/health-effects-of-climate-change-hecc-report.

[8] Mark P. Robertson et al., “Comparing Models for Predicting Species’ Potential Distributions: A Case Study Using Correlative and Mechanistic Predictive Modelling Techniques,” Ecological Modelling 164, no. 2-3 (June 2003): 153–67, https://doi.org/10.1016/s0304-3800(03)00028-0.

[9] Lucy Gilbert, “The Impacts of Climate Change on Ticks and Tick-Borne Disease Risk,” Annual Review of Entomology 66, no. 1 (January 7, 2021): 373–88, https://doi.org/10.1146/annurev-ento-052720-094533.

[10] Centre for Climate and Health Security and UK Health Security Agency, UK Government, “Health Effects of Climate Change (HECC) Report,” December 19, 2024, https://www.gov.uk/guidance/health-effects-of-climate-change-hecc-report.

[11] Lucy Gilbert, “The Impacts of Climate Change on Ticks and Tick-Borne Disease Risk,” Annual Review of Entomology 66, no. 1 (January 7, 2021): 373–88, https://doi.org/10.1146/annurev-ento-052720-094533.

[12] Withers, A.J., Croft, S., Budgey, R., Warren, D.A. & Johnson, N. (2025) Modelling vector and host distributions to inform potential disease risk: A case study of West Nile virus in the United Kingdom. Medical and Veterinary Entomology, 39(4), 842–862. Available from: https://doi.org/10.1111/mve.12825

[13] Arran J. Folly et al., “Emerging Threats to Animals in the United Kingdom by Arthropod-Borne Diseases,” Frontiers in Veterinary Science 7, no. 20 (February 4, 2020), https://doi.org/10.3389/fvets.2020.00020.

[14] The Met Office, “Climate Change and Health,” January 6, 2023, https://www.metoffice.gov.uk/blog/2023/climate-change-and-health.

[15] Isabel Oliver, “Understanding the Health Effects of Climate Change,” UK Health Security Agency (blog), November 9, 2021, https://ukhsa.blog.gov.uk/2021/11/09/understanding-the-health-effects-of-climate-change/.

[16] Withers, A.J., Croft, S., Budgey, R., Warren, D.A. & Johnson, N. (2025) Modelling vector and host distributions to inform potential disease risk: A case study of West Nile virus in the United Kingdom. Medical and Veterinary Entomology, 39(4), 842–862. Available from: https://doi.org/10.1111/mve.12825

[17] Isabel Oliver, “Understanding the Health Effects of Climate Change,” UK Health Security Agency (blog), November 9, 2021, https://ukhsa.blog.gov.uk/2021/11/09/understanding-the-health-effects-of-climate-change/.

[18] Centre for Climate and Health Security and UK Health Security Agency, UK Government, “Health Effects of Climate Change (HECC) Report,” December 19, 2024, https://www.gov.uk/guidance/health-effects-of-climate-change-hecc-report.

[19] Dr. Katharine Dow, “Links between Climate Change and Health in Scotland” (The Scottish Parliament, July 22, 2025), https://www.parliament.scot/chamber-and-committees/research-prepared-for-parliament/research-briefings/2025/7/22/links-between-climate-change-and-health-in-scotland/pdf.

[20] The Highland Council, “Love the Outdoors? Know the Score about Ticks,” 2022, https://www.highland.gov.uk/info/1211/animal_welfare_and_pest_control/640/ticks.

[21] The Met Office, “Climate Change and Health,” January 6, 2023, https://www.metoffice.gov.uk/blog/2023/climate-change-and-health.

[22] The Scottish Government, “Scottish National Adaptation Plan 2024 – 2029 . ” (2024), https://www.gov.scot/publications/scottish-national-adaptation-plan-2024-2029-2/.

[23]  Withers, A.J., Croft, S., Budgey, R., Warren, D.A. & Johnson, N. (2025) Modelling vector and host distributions to inform potential disease risk: A case study of West Nile virus in the United Kingdom. Medical and Veterinary Entomology, 39(4), 842–862. Available from: https://doi.org/10.1111/mve.12825

[24] Centre for Climate and Health Security and UK Health Security Agency, UK Government, “Health Effects of Climate Change (HECC) Report,” December 19, 2024, https://www.gov.uk/guidance/health-effects-of-climate-change-hecc-report.

[25] The Met Office, “Climate Change and Health,” January 6, 2023, https://www.metoffice.gov.uk/blog/2023/climate-change-and-health.

[26] Lucy Gilbert, “The Impacts of Climate Change on Ticks and Tick-Borne Disease Risk,” Annual Review of Entomology 66, no. 1 (January 7, 2021): 373–88, https://doi.org/10.1146/annurev-ento-052720-094533.

[27] Arran J. Folly et al., “Emerging Threats to Animals in the United Kingdom by Arthropod-Borne Diseases,” Frontiers in Veterinary Science 7, no. 20 (February 4, 2020), https://doi.org/10.3389/fvets.2020.00020.

[28] The Met Office, “Climate Change and Health,” January 6, 2023, https://www.metoffice.gov.uk/blog/2023/climate-change-and-health.

[29] The Scottish Government, “Scottish National Adaptation Plan 2024 – 2029 . ” (2024), https://www.gov.scot/publications/scottish-national-adaptation-plan-2024-2029-2/.

Key Definitions

For the HCCROA, the terms risk and opportunity are used in specific ways. Risk refers to the potential for climate change to cause harm to people, nature, buildings, infrastructure, and communities. Opportunity refers to the potential for climate change to alter conditions in ways that could be advantageous for certain activities, sectors, or places in the Highland region, relative to current conditions. These opportunities may arise alongside significant risks and do not offset or negate them.

The assessment also highlights a second kind of opportunity: opportunities for action. The HCCROA refers to options for regional collaboration, which are distinct from opportunities arising directly from climate change. Greater benefits may be realised from coordinated action to reduce risks than from relying on limited advantages associated with changing climate conditions themselves.

 

Mental Health

Climate change is a difficult topic to engage with, and Highland Adapts appreciates that this report presents potentially upsetting information. Visit the Highland Mental Wellbeing website to learn about mental health services, information, and training available in the Highland region.

 

Project Funding and Disclaimers

Core Highland Adapts funding is provided by its partner organisations. The HCCROA was partially funded by the Scottish Government’s Climate Ready Regions Grant. The views expressed in this document are not necessarily those of the Scottish Government. Its members, servants or agents accept no liability whatsoever for any loss or damage arising from the interpretation or use of the information, or reliance upon views contained herein.

The HCCROA is a product of the Highland Adapts partnership, conducted with support from Joseph Perry Consulting, Highland Adapts partner organisations, and other regional and national contributors. The analysis, findings, and conclusions presented in the HCCROA do not necessarily reflect the views of Highland Adapts partner organisations. The HCCROA is provided for general information and should not be regarded as a substitute for professional or technical advice. Highland Adapts, Joseph Perry Consulting, the report authors, and report contributors accept no responsibility for any loss or damage arising from the use or interpretation of information contained within the HCCROA.

This page was last updated on 3 Mar, 2026.