What is Lyme disease?
Lyme disease (also known as Lyme borelliosis) is an infection caused by a spiral shaped bacterium called borrelia burgdorferi that is transmitted by a bite from a tick carrying the bug. It is named after the town in Connecticut, USA where the first cases of the condition were identified.
The infection is generally mild, affecting only the skin, but can sometimes be more severe, leading to more serious illness.
Ticks are tiny, spider-like creatures that are commonly found in woodland, moorland and other grassy areas. These areas have the right conditions for maintaining the tick life cycle, ie. high humidity in leaf litter or dead vegetation. They are also found in some animals, such as field mice, voles, sheep, deer and horses.
The ticks feed by biting and attaching to the skin and sucking blood from animals such as sheep and deer. If ticks feed on an animal infected with the bacteria B. burgdorferi, the animals will also become infected, and can pass on the bacteria to people and domestic animals.
Unlike humans and domestic animals, infected wild animals do not seem to show symptoms of Lyme disease.
In general, the longer the tick has been attached to the skin, the greater the risk of passing on infection. It seems that ticks need to be attached and to have been feeding for quite some time. If a tick is removed as soon as it bites, then the risk of infection is minimal.
One of its most famous victims recently was former US president George W Bush, who contracted the disease after a tick bite in 2006, but was treated successfully and did not suffer any serious ill-effects.
How do people get Lyme disease?
Lyme disease has been reported in North America, Europe, Australia, China and Japan. Infected ticks are most likely to be encountered in heath land and lightly forested areas of North America and Northern Europe. Ramblers, campers and those who work in such areas, especially if they come into contact with large animals, are at greatest risk of being bitten by ticks and of going on to develop the disease. Cases of Lyme disease appear in Ireland every year, according to the Health Protection Surveillance Centre (HPSC).
What symptoms can Lyme disease cause?
Many infected people have no symptoms at all. The commonest evidence of infection is a rash that is seen in about three-quarters of infected people. This red, raised skin rash develops between three days and a month after a tick bite and spreads outwards from the initial bite site. This rash can last up to a month and can be several inches in diameter. People can also complain of 'flu-like’ symptoms such as headache, sore throat, neck stiffness, fever, muscle aches and general fatigue. Occasionally, there may be more serious symptoms involving the nervous system, joints, the heart or other tissues.
Are there complications from the disease?
Complications following Lyme disease are uncommon, and tend to occur less frequently in Europe than in North America, according to the HPSC. Complications tend to occur some time after initial infection and are common in people who did not realise they had been infected or who were not initially treated. Complications can affect different parts of the body, including:
Joints: swelling and pain in large joints (arthritis) which can recur over many years
Heart: inflammation of heart muscle (myocarditis) with irregularities of heart rhythm
Eye: conjunctivitis and eye pain
Nervous system: numbness and weakness, meningitis/encephalitis and Bell's palsy (facial paralysis).
Diagnosing Lyme disease
Lyme disease is diagnosed by medical history and physical examination. Diagnosis can be difficult if there has been no rash (erythema migrans). The infection is confirmed by special blood tests.
How common is Lyme disease?
There is no legal requirement on doctors to report cases of Lyme disease to the authorities so it is difficult to know. A number of cases are diagnosed each year, but the true figure is unknown, according to the HPSC. In the UK, about 300 laboratory-confirmed cases are reported annually. However, true figures could be much higher.
Who is at risk?
Lyme disease can affect anyone but is commonest among ramblers, hill-walkers, hikers, campers and others whose leisure activities or work takes place in heath land or light woodland areas or brings them in contact with certain animals, eg. deer. Summer and autumn is the period when most cases occur.
Is there a treatment?
Antibiotics such as doxycycline or amoxicillin are effective at clearing the rash and helping to prevent the development of complications. They are generally given for up to three weeks. If complications develop, intravenous antibiotics may need to be used.
Is there a vaccine available?
Currently there is no vaccine available against human Lyme disease in Ireland.
Protection against Lyme disease
The best protection against Lyme disease it to protect yourself against tick bites when walking in grassy, bushy or woodland areas. Cover your arms and legs, wear long trousers tucked into socks or boots and long-sleeved shirts with cuffs fastened. You should wear shoes or boots rather than open-toed sandals. Use insect repellent on clothes, or on limbs.
Inspect skin and clothing for ticks every three to four hours and check children's skin and clothes frequently.
At the end of the day, check your and your children's bodies thoroughly for attached ticks, including skin folds such as armpits and groins.
Remove a tick as soon as you see one attached to the skin. Grasp it as close to your skin as possible, with tweezers if necessary. Take care to remove it entirely using gentle but firm pressure, as the tick's head can break off and be left behind.
It is not recommended that antibiotics are given to prevent the transmission of Lyme disease following a tick bite. Treatment is usually required only if the area becomes inflamed. Your doctor can advise you on this. See your doctor if you develop an unusual rash or become unwell with other symptoms. Let your doctor know if you have been exposed to ticks.
For for information on Lyme disease and other infectious diseases see...http://www.hpsc.ie
Further information on Lyme disease and other infectious diseases can be found on www.hpsc.ie or the websites of the UK's Health Protection Agency at http://www.hpa.org.uk/ and the US Centers for Disease Control and Prevention at http://www.cdc.gov/.