Lyme disease is an infection with a bacterium (germ). Humans can get Lyme disease if they are bitten by an infected tick. The first and typical symptom is usually a rash that spreads out from the site of the tick bite. Left untreated, the bacteria can spread to other areas of the body. In some cases this can cause serious symptoms - often months after the initial tick bite. A course of antibiotics will usually clear the infection.
What is Lyme disease?
Lyme disease is an infection with a bacterium (germ) called Borrelia. There are various subtypes of Borrelia bacteria but Borrelia burgdorferi causes most cases of Lyme disease. The bacterium is passed to humans from infected ticks. It is called Lyme disease because in 1975 in a town called Old Lyme in the USA there was an outbreak of arthritis in young children which was found to be due to this infection. This was the first time that this bacterium was proved to be the cause of a medical condition.
Where is Lyme disease a problem?
Since 1975, thousands of cases have been reported in the USA. Lyme disease is less common in the UK. In 2008 tests confirmed about 1,100 cases in the UK. However, the total number of UK cases each year is unknown, but may number in the thousands. This is because many cases are not formally diagnosed and clear away without any treatment. Most people affected are forestry workers and other outdoor workers. However, visitors and holidaymakers to countryside areas where ticks are found are at risk.
How do humans get Lyme disease?
The bacterium that causes Lyme disease lives in certain animals. These are mainly rodents such as mice, some birds and some other small animals. The bacterium is usually harmless to the animals.
Ticks are small insect-like creatures, about the size of a pinhead. Ticks feed by biting the skin and sucking blood from animals such as mice, and sometimes humans. In this way, some ticks get infected with the bacterium that causes Lyme disease. If an infected tick bites a human, then the bacteria may be passed into the human. The bacterium that causes Lyme disease is not passed from person to person. Note: most ticks in the UK are not infected by the bacterium that causes Lyme disease. Therefore, most tick bites will not cause Lyme disease.
It usually takes 24-48 hours for bacteria in the tick to pass into the human after being bitten. (Ticks are tiny and 'cling on' to you once they bite you. They then suck blood and 'engorge' with blood which they feed off. The bacteria are normally carried in their gut, and only travel up to their mouth and into your skin once they have been fed and are engorged. This normally takes about 24 hours, but can be less if the tick was already partially fed.) Therefore, if you remove a tick soon after being bitten - within 24 hours - you are much less likely to develop Lyme disease, even if it was an infected tick.
So, it is only certain infected ticks that bite, and are not noticed clinging on to your skin, that usually cause Lyme disease. However, ticks are very small, and often do not hurt when they bite. It is quite easy to have a tick bite without you noticing. For example, on your leg or back. Many people who develop Lyme disease cannot remember being bitten by a tick.
Once bacteria are passed from the infected tick into your skin, they then multiply and travel in the bloodstream to other parts of the body to cause symptoms. The parts of the body that are mainly affected by this bacteria are: skin, joints, nerves and heart.
What are the symptoms of Lyme disease?
The symptoms and effects of Lyme disease can be divided into three stages:
Stage one - early reaction to the local skin infection
This can develop anytime between 2 and 30 days after being bitten by an infected tick.
Rash. The classical symptom of Lyme disease is a typical rash called erythema migrans. However, this does not always occur. It probably occurs in between three and eight out of ten cases.
The rash is usually a single circular red mark that spreads outwards slowly over several days. The circle gets bigger and bigger with the centre of the circle being where the tick bite occurred. As it spreads outwards a paler area of skin emerges on the inner part of the circle. Therefore, the rash is often called a 'bulls eye' rash.
The rash may just be a few centimetres in diameter, but may grow to up to 30 cm.
The rash is not usually painful or particularly itchy. You may not even notice it if it is on your back. Without treatment, erythema migrans typically fades within 3-4 weeks. However, just because the rash fades does not necessarily mean the infection has cleared from the body.
Note: many insect bites cause a small red blotchy 'allergic' rash to appear soon after the skin is bitten. These soon go away. The rash of erythema migrans is different in that it usually develops several days after the bite, and has a typical spreading circular appearance.
Flu-like symptoms occur in about half of cases. Symptoms include tiredness, general aches and pains, headache, fever, chills and neck stiffness. These symptoms are often mild and go within a few days even without treatment (but the infection may not have gone).
In some cases, the infection does not progress any further, even without treatment, as the immune system may clear the infection. However, in about half of cases that are not treated, the disease progresses to stage two.
Stage two - early disseminated disease
This may develop in untreated people weeks or months after the bite. Symptoms are variable but can include one or more of the following:
Joint problems in one or more joints. They most commonly affect the knee joint or jaw joint (temporomandibular joint). The severity of joint problems can range from episodes of mild joint pains, to severe joint inflammation (arthritis) causing a lot of pain. Episodes of joint inflammation last, on average, three months.
Nerve and brain problems. Some affected people develop inflammation to nerves, particularly the nerves around the face. This may cause the nerve to stop working and cause facial weakness. Meningitis and encephalitis (brain inflammation) may occur.
Heart problems. Some affected people develop inflammation of the heart (myocarditis) and other heart problems. This may cause symptoms such as dizziness, breathlessness, chest pain and palpitations.
Rash. Several areas of the skin (not where the tick bite occurred) may develop a rash similar to erythema migrans (described above). These 'secondary' rashes tend to be smaller than the original stage one rash. These tend to fade within 3-4 weeks.
Rarely, other organs such as the eyes, kidneys and liver are affected.
Stage three - chronic (persistent) Lyme disease
This may develop months to years after infection. It may develop after a period of not having any symptoms. A whole range of symptoms have been described in joints, nerves, brain and heart. The brain problems may include mild confusion, and problems with memory, concentration, mood, sleep, personality and/or language. There is controversy as to whether Lyme disease may cause depression, anxiety, schizophrenic-like illness, bipolar disorder and dementia.
How is Lyme disease diagnosed?
In most cases, Lyme disease is diagnosed in stage one of the disease by the typical symptoms. That is, the typical rash, sometimes also with a flu-like illness, in someone who has been bitten by a tick. Other tests are not needed in this situation and treatment is usually given. The diagnosis of stage two or three is more difficult. Blood and urine tests and skin tests are helpful (but not always conclusive) in diagnosing the disease if it is suspected from the symptoms.
What is the treatment for Lyme disease?
A course of antibiotics will usually clear the infection. The type of antibiotic, and the length of the course can vary depending on individual circumstances. Your doctor will advise. Most people are diagnosed in stage one when treatment will clear the symptoms and prevent the development into stages two or three.
Can Lyme disease be prevented?
The following will reduce your risk of developing Lyme disease:
- If possible, avoid areas where infected ticks live - particularly in the summer months. When out in the countryside, keep to paths and away from long grass or overgrown vegetation, as ticks crawl up long grass in their search for a feed.
- If living or visiting a tick-prone area, when outdoors wear appropriate clothing. That is: long-sleeved shirts and long trousers tucked into socks. Light-coloured fabrics are useful, as it is easier to see ticks against a light background.
- Inspect your entire body each day to check for ticks and remove any that are on the skin. Make sure that children's head and neck areas, including scalps, are properly checked.
- Consider using a tick repellent spray, cream, etc, on your skin that contains N,N-diethyl-m-toluamide (DEET).
- Check that ticks are not brought home on clothes.
- Check that pets do not bring ticks into the home on their fur.
To remove a tick that is attached to your skin:
- Gently grip the tick as close to the point of attachment to the skin as possible. Do this preferably using fine-toothed tweezers or forceps, or a tick removal device.
- Pull steadily upwards, away from the skin. Take care not to crush the tick. For a diagram, see: www.lymediseaseaction.org.uk/information/tick_removal.htm
Inexpensive tick removal devices may be available at veterinary surgeries and pet supply shops, and are useful for people who are frequently exposed to ticks. These should be used in accordance with the manufacturers' instructions.
- Burn the tick off (for example, using lighted cigarette ends or match heads).
- Apply petroleum jelly, alcohol, nail varnish remover, or other substances (as this may stimulate the tick to regurgitate potentially infected material into the skin, which may increase the risk of transmission of infection).
- Use your fingers to pull the tick off, and don't squeeze the tick.
After removal, clean the skin with soap and water, or skin disinfectant, and wash hands.
What is the outcome (prognosis)?
If you are treated with antibiotics in stage one of the disease, you have a very good chance of a complete cure with no further problems.
If you are not treated in stage one, about 8 in 10 develop some symptoms of stage two or three. However, these are often mild and transient symptoms such as a skin rash or mild joint pains. Some people develop more severe symptoms if they progress to stage two or three. Treatment with antibiotics during stage two or three is also usually curative. However, a prolonged course of antibiotics may be needed.
Some people report ongoing symptoms that may be triggered by Lyme disease even when the infection has been treated with antibiotics. This has been called 'post-Lyme disease syndrome'. Medical opinion is divided on whether ongoing symptoms are due to inadequately treated infection, or to another cause such as an autoimmune condition. That is, it may be due to a reaction of the immune system that does not 'switch off' even when the bacteria causing the infection have been cleared. Symptoms of 'post-Lyme disease syndrome' that have been reported include: tiredness, joint or muscle pains, headaches, hearing loss, vertigo, mood disturbances, pins and needles and difficulty sleeping.
Further help and information
Lyme Disease Action
Lyme Disease Action is striving for the prevention and treatment of Lyme disease and associated tick-borne diseases.
The Tick Alert campaign aims to raise awareness of tick-borne diseases both at home and abroad. Tick Alert warns UK holidaymakers and travellers to be aware of the infections that ticks can cause, including Lyme disease which is prevalent in the UK and tick-borne encephalitis (TBE) in mainland Europe.
EUCALB - European Union Concerted Action on Lyme Borreliosis
A pan-European information site supported by an advisory board comprising an expert group of physicians and biologists from across Europe. Provide up-to-date information on Lyme borreliosis (Lyme disease) in Europe in the form of short reviews and latest publications. Although available and of interest to the general public, its primary targets are healthcare professionals, scientists and students
Further reading & references
- Lyme disease, Clinical Knowledge Summaries (January 2010)
- Meyerhoff J. Lyme disease. eMedicine. Article dated July 2009
- Wormser GP, Dattwyler RJ, Shapiro ED, et al; The clinical assessment, treatment, and prevention of lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis. 2006 Nov 1;43(9):1089-134. Epub 2006 Oct 2.; (reviewed 22/4/2010 by IDSA - no changes made to guidelines)
- Lyme borreliosis/Lyme disease, Health Protection Agency
|Original Author: Dr Tim Kenny||Current Version: Dr Tim Kenny|
|Last Checked: 24/03/2010||Document ID: 4038 Version: 44||© EMIS|
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