Lyme disease, or Lyme borreliosis, is a bacterial infection spread to humans by infected ticks.
Ticks are tiny spider-like creatures found in woodland and heath areas. They feed on the blood of birds and mammals, including humans. Ticks that carry the bacteria responsible for Lyme disease are found throughout the UK and in other parts of Europe and North America.
It’s estimated there are 2,000 to 3,000 new cases of Lyme disease in England and Wales each year. About 15% of cases occur while people are abroad.
Lyme disease can often be treated effectively if it’s detected early on. But if it’s not treated or treatment is delayed, there’s a risk you could develop severe and long-lasting symptoms.
What are the signs and symptoms of Lyme disease?
The rash is often described as looking like a bull’s-eye on a dart board. The affected area of skin will be red and the edges may feel slightly raised.
The size of the rash can vary significantly and it may expand over several days or weeks. Typically it’s around 15cm (6 inches) across, but it can be much larger or smaller than this. Some people may develop several rashes in different parts of their body.
However, around one in three people with Lyme disease won’t develop this rash.
Some people with Lyme disease also experience flu-like symptoms in the early stages, such as tiredness (fatigue), muscle pain, joint pain,headaches, a high temperature (fever), chills andneck stiffness.
More serious symptoms may develop several weeks, months or even years later if Lyme disease is left untreated or is not treated early on. These can include:
pain and swelling in the joints (inflammatory arthritis)problems affecting the nervous system – such as numbness and pain in your limbs, paralysis of your facial muscles, memory problems and difficulty concentratingheart problems – such as inflammation of the heart muscle (myocarditis) or sac surrounding the heart (pericarditis), heart block and heart failureinflammation of the membranes surrounding the brain and spinal cord (meningitis) – which can cause a severe headache, a stiff neck and increased sensitivity to lightSome of these problems will get better slowly with treatment, although they can persist if treatment is started late.
A few people with Lyme disease go on to develop long-term symptoms similar to those offibromyalgia or chronic fatigue syndrome. This is known as post-infectious Lyme disease. It’s not clear exactly why this happens, but it’s likely to be related to overactivity of your immune system rather than persistent infection.
You should see your GP if you develop any of the symptoms described above after being bitten by a tick, or if you think you may have been bitten. Make sure you let your GP know if you’ve spent time in woodland or heath areas where ticks are known to live.
Diagnosing Lyme disease is often difficult as many of the symptoms are similar to other conditions. A spreading rash some days after a known tick bite should be treated with appropriate antibiotics without waiting for the results of a blood test.
Blood tests can be carried out to confirm the diagnosis after a few weeks, but these can be negative in the early stages of the infection. You may need to be re-tested if Lyme disease is still suspected after a negative test result.
In the UK, two types of blood test are used to ensure Lyme disease is diagnosed accurately. This is because a single blood test can sometimes produce a positive result even when a person doesn’t have the infection.
How do you get Lyme disease?
If a tick bites an animal carrying the bacteria that cause Lyme disease, the tick can also become infected. The tick can then transfer the bacteria to a human by biting them.
Ticks can be found in any areas with deep or overgrown vegetation where they have access to animals to feed on.
They’re common in woodland and heath areas, but can also be found in gardens or parks.
Ticks don’t jump or fly, but climb on to your clothes or skin if you brush against something they’re on. They then bite into the skin and start to feed on your blood.
Generally, you’re more likely to become infected if the tick remains attached to your skin for more than 24 hours. But ticks are very small and their bites are not painful, so you may not realise you have one attached to your skin.
Most tick bites happen in late spring, early summer and autumn because these are the times of year when most people take part in outdoor activities, such as hiking and camping.
Diagnosing Lyme disease is often difficult as many of the symptoms are similar to other conditions.
Blood tests can be carried out to confirm the diagnosis after a few weeks, but these can be negative in the early stages of the infection and a person may need to be re-tested if Lyme disease is still suspected after a first negative test result. This is true of many infectious diseases and is not a peculiarity of Lyme disease.
The tests used in the UK are used across Europe and the US, and the PHE laboratory participates in a Europe wide External Quality Assurance scheme which compares the results obtained by major European Health Service laboratories to ensure that different tests are as sensitive and reproducible as possible between each centre. A number of private laboratories offer their own special tests, but these are not subject to the same stringent quality control.
PHE are working with national and international partners to study new tests methodologies that may be useful in early disease, and to distinguish active infection from past exposure. All laboratory tests have to be interpreted in the context of each patient and the stage of their illness, in exactly the same way as any other medical investigation.
It is extremely important that patients are reviewed properly by a medical practitioner on the whole symptom complex and presentation of their illness, and not treated on the basis of a single laboratory test without supporting clinical evidence.
A number of private laboratories abroad offer tests for Lyme disease, but the value of many of these tests has not been published or verified.
– DR WILL WELFARE, CONSULTANT WITH THE GREATER MANCHESTER HEALTH PROTECTION TEAM, PUBLIC HEALTH ENGLAND