Lyme disease is caused by the Borrelia burgdorferi bacteria. The bacteria are present in the digestive systems of many different animals including mice, deer, pheasants and blackbirds.
If a tick (a tiny spider-like creature) bites an animal that has the bacteria, the tick can also become infected with it. The tick can transfer the bacteria to a human by biting them and feeding on their blood.
Ticks are very small and their bites are not painful, so you may not realise that you have one attached to your skin. However, there is a higher risk that you will become infected if the tick remains attached to your skin for more than 36 hours.
Once infected, the bacteria moves slowly through your skin and into your blood and lymphatic system. The lymphatic system helps fight infection and is made up of a series of vessels (channels) and glands (lymph nodes).
Left untreated, the bacteria that causes Lyme disease can damage the joints and the nervous system, leading to symptoms of mid- and late-stage Lyme disease.
Groups at risk
The groups most at risk of getting Lyme disease include those who work in woodland and heath areas and those who take part in activities in these areas. For example:
- hikers
- campers
- farmers
- forestry workers
- soldiers
- gamekeepers
Most tick bites occur in late spring, early summer and during the autumn because these are the times of year when most people take part in outdoor activities, such as hiking and camping.
