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 exists in animals such as deer and mice and is passed to humans via ticks feeding off the infected animals. 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 recognised to be the cause of a medical condition. That said, there is evidence of the bacterium in Victorian Britain so it has probably been around for a very long time.
Where is Lyme disease a problem?
Since 1975, thousands of cases have been reported in the USA. However, Lyme disease is not as common in the UK as most ticks here are not infected with the bacteria. Some 1500 cases are reported in the UK each year although the actual number is estimated to be much higher as most incidents are not correctly diagnosed. Most cases in the UK occur around high population of deer and where infected ticks are found - the New Forest, Thetford Forest and the Scottish Highlands. Most people affected are forestry workers and other outdoor workers, but visitors and holiday makers to these areas are at risk.
How do humans get Lyme disease?
Most cases of Lyme disease are transmitted by nymphal ticks, which feed in the late spring and early summer ("Nymphal" refers to one of the early stages in the life cycle of ticks). As a result, this is the time when Lyme disease is generally acquired. Nymphal deer ticks are small -- about the size of a pin head-- and so their presence is often missed.
Ticks feed off their host animals and then are able to carry the infection to a new host, including humans. The bacterium in the tick is usually harmless to the carrier animals themselves. The bacterium that causes Lyme disease is not passed from person to person.
It normally takes 24 to 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 and this 'clinging' means they will typically resist being washed off. 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 feeding for more than 24 hours and are engorged. Therefore, if you remove a tick soon after being bitten - within 24 hours - you are very unlikely to develop Lyme disease, even if it was an infected tick.
So it is only infected ticks that carry Lyme and they have to be in place quite a while. However ticks are tiny and because they inject their own 'anaesthetic' into the wound they mostly 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 and this is certainly true in my case.
What precautions should you take?
Surveys have indicated that around 30% of ticks in the UK carry the bacterium which causes Lyme disease, so although it is relatively little-known, the risks to us all are actually quite serious. If you are unlucky enough to have been bitten by an infected tick, in some cases you will develop a tell-tale 'bullseye' rash. Your GP will probably recognise this and treat you with anti-biotics which will almost certainly end the problem, although he should ensure the dose is of sufficient strength.
In many cases (mine included) there is no rash. If you start to feel constantly nauseous, have difficulties with your heart and/or presistent 'flu like' symptoms you should seek medical advice. I never had these symptoms but did have severe headaches, neck pain and fatigue. I also began to develop difficulties with walking and balance which deteriorated significantly, so you should be aware that this disease can manifest itself in different forms.
The best form of defence against the disease is to ensure you wear long trousers and sleeves when in potentiallly infected areas (forests and such like) and to tuck trousers into boots. Using an insect repellent on exposed skin is also worthwhile. Prevention is definitely better than cure!
The following information sheets by the charity 'Lyme Disease Action' provide a good summary of Lyme in the UK. To view the full item click on the link below the image (a new window will open).
Lyme Disease in Britain Ticks in Britain Click here for more fact sheets
