Lyme disease is a bacterial infection that is spread to human by infected ticks. Ticks are small, spider-shaped creatures that feed on the blood of mammals, including humans.
The most common symptom of Lyme disease is a red skin rash that looks similar to a bull's eye on a dart board. However, if Lyme disease is left untreated, further symptoms can follow including:
- a high temperature (fever) of 38ºC (100.4ºF) or higher
- muscle pain
- joint pain and swelling
- neurological symptoms, such as temporary paralysis of the facial muscles
A person with Lyme disease cannot spread disease to another through normal social contact.
How common is Lyme disease?
Lyme disease is not a common infection. It is estimated that there are between 50 and 100 cases in Ireland each year.
The ticks that cause Lyme disease are commonly found in woodland and heathland areas. This is because these types of habitats have a high number of tick-carrying animals, such as deer, mice and sheep.
Due to their breeding patterns, the tick population is highest in late spring and early summer.
Ticks can also be found in rural areas in many other countries, including:
There is a widely held misconception that the outlook for Lyme disease is poor and that the condition cannot be treated. This is not the case.
If Lyme disease is diagnosed in its early stages, it can be treated with antibiotics, and the outlook for the condition is excellent. Most people will make a full recovery within a couple of days.
Even if more serious symptoms develop, they can usually be cured with antibiotics, although a longer course will be required.
A vaccine for Lyme disease was introduced in 1998, but it has since been withdrawn by the manufacturer due to controversies over alleged side effects.
The best way to prevent Lyme disease is to take sensible precautions when you are in areas that are known to have a high tick population, such as wearing long-sleeved shirts, and using insect repellent. See the Lyme disease - prevention section for more information.
The symptoms of Lyme disease usually fall into three distinct stages:
- early-stage Lyme disease,
- mid-stage Lyme disease, and
- late-stage Lyme disease.
You should only experience symptoms of mid- and late-stage Lyme disease if you are not treated with antibiotics during the initial stage of the condition.
Early-stage Lyme disease
The symptoms of early-stage Lyme disease develop between 3-30 days after being bitten by an infected tick.
The most common symptom of early-stage Lyme disease is the appearance of a distinctive skin rash that is known as erythema migrans.
Erythema migrans looks like a bull's eye and develops at the site of the tick bite. The skin affected by the rash will look red and feel slightly raised to the touch. The size of the rash can range from between 2-30 cm (0.7-12 inches).
Other symptoms of early-stage Lyme disease include:
- muscle pain,
- joint pain,
- fever and/or chills, and
- neck stiffness.
Mid-stage Lyme disease
The symptoms of mid-stage Lyme disease usually develop many weeks, or sometimes several months, after being bitten by an infected tick. However, they usually only affect some people who were not treated with antibiotics at an early stage.
In 60% of untreated cases of Lyme disease, people will get symptoms that resemble arthritis, such as:
- joint pain, and
- inflammation (swelling) of the joints.
In 10% of untreated cases, people will get neurological symptoms (symptoms that affect the nervous system). These symptoms include:
- numbness and pain in your limbs,
- temporary paralysis of your facial muscles - usually only one half of the face is affected (this symptom is also known as Bell's palsy),
- impaired memory,
- difficulty concentrating, and
- changes in personality.
Some people will also develop meningitis, which is a serious condition where the meninges (the protective membranes that surround the brain and spinal cord) become inflamed. The symptoms of meningitis include:
- severe headache,
- stiff neck, and
- increased sensitivity to light (photophobia).
Late-stage Lyme disease
In a small minority of untreated cases, the symptoms of late-stage Lyme disease can develop after many months, or even years.
As with mid-stage Lyme disease, the symptoms can affect both the joints and the nervous system. The symptoms can include:
- chronic (long-lasting) joint pain and swelling,
- impaired memory,
- difficulties concentrating, and
Lyme disease is caused by bacteria called Borrelia burgdorferi. The bacteria are present in the digestive systems of many different animals including:
- pheasants, and
If a tick bites an animal that has the bacteria, they can also become infected with it. The tick can then transfer the bacteria to a human by biting them and feeding on their blood.
In general, the longer the tick has been attached to the skin, the greater the risk of passing on infection – it is uncommon for the infection to be passed in the first hours after a bite meaning it is important to look for ticks and to remove them.
The problem is that the ticks are very small and they do not cause pain so it can be difficult to realise that you have a tick attached to your skin.
Once an infection has taken place, the bacteria move slowly through your skin and into your blood and lymphatic system. The role of the lymphatic system is to fight infection, and it is made up of a series of vessels and glands (lymph nodes). Left untreated, the bacteria can damage the joints and the nervous system, leading to symptoms of mid- and late-stage Lyme disease.
Risk factors for Lyme disease include any activity, or occupation, that involves prolonged exposure to woodland and heath land areas such as:
- forestry work,
- soldiers, and
Lyme disease can be a difficult condition to diagnose, particularly in its latter stages, because its symptoms are also shared by other, more common conditions, such as infections, or arthritis. While the characteristic skin rash can provide an important clue, not everyone with Lyme disease will develop the rash.
If you do not develop the rash, you will need to have some tests so that your GP can confirm, or rule out, a diagnosis.
The first test that you will have is a type of blood test that is known as an enzyme-linked immunosorbent assay (ELISA) test. The ELISA test is designed to look for specific antibodies that are produced by your immune system to kill the Borrelia burgdorferi bacteria.
The ELISA test is not 100% accurate, and can sometimes produce a positive result even when a person is not infected with Lyme disease (a false-positive result). As a result of this, an ELISA test is followed by a further test called the Western Blot test.
Western Blot test
The Western Blot test involves taking a small sample of your blood. The blood is placed in a special machine that works in a similar way to a blender by separating and collecting antibodies.
If both the results of the ELISA test and the Western Blot test are positive, a confident diagnosis of Lyme disease can usually be made.
Antibiotic tablets (oral antibiotics) are recommended for the treatment of early-stage Lyme disease. Most people will require a 2-3 week course of antibiotics. If you are prescribed antibiotics, it is important that you finish the course even if you are feeling better because this will ensure that all the bacteria are destroyed.
Mid- and late-stage Lyme disease can also be treated with antibiotics. If your symptoms are particularly severe, antibiotic injections (intravenous antibiotics) may be used. Most people with mid- and late-stage Lyme disease will require a prolonged course of antibiotics.
The antibiotics that are used to treat Lyme disease (both oral and intravenous) can make your skin more sensitive to sunlight. Therefore, you should avoid prolonged exposure to the sun and avoid using tanning equipment until you have finished the course.
Pregnancy and breastfeeding
If you are pregnant and get Lyme disease, treatment with antibiotics will not pose any additional risk to your unborn baby.
As the bacteria that cause Lyme disease cannot be passed on through breast milk, it is safe to continue breastfeeding if you have Lyme disease.
Currently, there is no vaccine available for Lyme disease.
The best way to prevent getting Lyme disease is to be aware of the risks when you visit areas where ticks are likely to be found, and to take sensible precautions.
Travellers to other European countries, or to North America, where the infection occurs more frequently than in these islands, should also be aware of the risks. It is important to remember that you can contract Lyme disease in Ireland and the UK.
You can reduce the risk of infection by:
- being aware of ticks and which areas they normally live in,
- wearing appropriate clothing in tick-infested areas (a long-sleeve shirt and trousers tucked into your socks),
- using insect repellents,
- inspecting your skin for ticks, particularly at the end of the day, including your head, neck, and skin folds (armpits, groin, and waistband),
- making sure that your children's head and neck areas, including scalps, are properly checked,
- checking that ticks are not brought home on your clothes, and
- checking that pets do not bring ticks into your home in their fur.
How to remove a tick
If you find a tick on your skin (or your child's skin), you should remove it by gently gripping it as close to the skin as possible, preferably using fine toothed tweezers, and pull steadily away from the skin.
Do not use a lighted cigarette end, a match head, or volatile oils to force the tick out. Some veterinary surgeries and pet supply shops sell inexpensive tick removal devices, which may be useful if you are frequently exposed to ticks.