Vector-borne diseases are infections spread by the bite of infected insects or animals, known as vectors. In the UK, vectors can include ticks, mosquitoes and some biting flies.

Lyme disease is the most common example in the UK, while diseases such as dengue fever and west nile virus are more commonly found in other parts of the world.

Worldwide, diseases spread by insects and animals cause more than 700,000 deaths each year and continue to have a significant impact on public health,  such as malaria, dengue fever and Japanese encephalitis.

Insects and animals that spread disease and the diseases they carry

  • Mosquitoes - malaria, dengue fever, zika virus disease, chikungunya, yellow fever and west nile virus disease.
     

  • Ticks - lyme disease, tick-borne encephalitis, babesiosis and anaplasmosis.
     

  • Fleas - plague and murine typhus.
     

  • Sandflies - leishmaniasis and sandfly fever.
     

  • Tsetse flies - african sleeping sickness.
     

  • Blackflies - river blindness (onchocerciasis).
     

  • Kissing bugs - chagas disease.
     

  • Mites - scrub typhus and rickettsialpox.
     

  • Lice - epidemic typhus, trench fever and relapsing fever.

In the UK, ticks are currently the vector of greatest concern because they can spread Lyme disease. View more information about the symptoms of lyme disease, where ticks are commonly found, and how to avoid tick bites during outdoor activities.

How is climate change affecting insects and animals that spread disease?

Climate change is bringing warmer temperatures and changing rainfall patterns across the UK.

These changes may create more favourable conditions for some disease-carrying insects and animals. As a result, existing disease-carrying species may spread to new areas, breeding seasons may become longer, and species not currently found in the UK could become established.

Monitoring insects and animals that spread disease

In the UK, organisations work together to monitor insects and animals that can spread disease, such as ticks and mosquitoes. This work is led by the UK Health Security Agency (UKHSA) and involves local authorities, scientists and environmental organisations.

Monitoring activities include:

  • tracking mosquito and tick populations

  • investigating unusual infections in people and animals

  • testing insects and animals for disease-causing germs

  • assessing how environmental factors, including climate change, may affect disease risks.

This helps identify new health threats early, supports planning and preparedness, and provides information and advice to healthcare professionals, local authorities and the public on how to prevent diseases such as Lyme disease and other infections spread by insects and animals.

Preventing diseases spread by insects and animals

The risk of diseases spread by mosquitoes in the UK is currently low. However, there are simple steps you can take to reduce the number of mosquitoes and other pests around your home.

  • Remove standing water regularly by emptying or covering containers such as water butts, buckets, plant saucers, bird baths and blocked gutters. Mosquitoes can breed in very small amounts of water, even in discarded items such as crisp packets.
     

  • Keep your garden tidy by cutting long grass and managing dense vegetation, which can provide shelter for ticks and other pests.
     

  • Prevent insects from entering your home by fitting window and door screens, repairing damaged screens and sealing gaps around doors and windows.
     

  • Protect your pets by following veterinary advice on tick and flea prevention, as pets can bring disease-carrying insects and animals into the home. Visit the British Veterniary Association (BVA) website for advice on tick and flea prevention.
     

  • Take precautions when travelling abroad by following destination-specific health advice and taking steps to prevent insect bites. View information about protecting your health when travelling abroad.

Last updated : 2 November 2026

The sheep tick (Ixodes ricinus) is the tick species of greatest public health concern in the UK.

Ticks can spread several diseases, but they are best known for transmitting lyme disease, which is caused by borrelia bacteria. Lyme disease is the most commonly reported tick-borne infection in England and Wales, with around 1,500 laboratory-confirmed cases reported each year. The actual number of cases is likely to be higher, as many people are diagnosed and treated without laboratory testing.

Ticks can also spread other, less common infections, including tick-borne encephalitis (TBE), which has been detected in parts of England. In some cases, tick bites have also been linked to alpha-gal syndrome, an allergy to red meat.

Symptoms of lyme disease

Symptoms can develop between 3 and 30 days after a tick bite and may include:

  • a spreading bullseye-shaped rash around the bite (although not everyone develops a rash)

  • flu-like symptoms, such as fever, headache and tiredness

  • facial weakness or drooping

  • nerve pain

  • numbness or tingling in the hands or feet

  • in rare cases, heart palpitations or swollen joints.

Lyme disease can be caught anywhere in the UK, but it is more common in southern England and the Scottish Highlands. Although some ticks carry the bacteria that cause lyme disease, most ticks are not infected, and being bitten by an infected tick does not always result in illness.

How to reduce the risk of tick bites

When spending time outdoors, you can help protect yourself by:

  • staying on clearly marked paths where possible

  • wearing long trousers and long-sleeved tops

  • wearing light-coloured clothing to make ticks easier to spot

  • using an insect repellent containing DEET and following the manufacturer's instructions

  • regularly checking your clothing and exposed skin for ticks.

Check for ticks after being outdoors

After activities such as walking, running, gardening, camping, picnicking or dog walking, carry out a thorough tick check.

Pay particular attention to:

  • armpits

  • groin area

  • behind the knees

  • around the waistband

  • wrists

  • back of the neck

  • hairline.

Adults are most commonly bitten on the legs, while children are more often bitten on the head and neck. More than one tick may be attached at the same time.

Removing a tick

If you find an attached tick, remove it as soon as possible using a tick removal tool or fine-tipped tweezers.

Grasp the tick as close to the skin as possible and pull upwards slowly and steadily. Avoid squeezing or crushing the tick during removal.

Prompt removal is important because the longer an infected tick remains attached, the greater the chance of disease transmission.

Last updated : 2 November 2026