Lyme disease

Ticks which feed on deer can carry Lyme disease in the US

Climate changes have been blamed for a doubling in the numbers of cases of Lyme disease in the UK since records began in 1986. BBC News Online examines an infection which is mainly associated with foreign climes.

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Lyme disesase is caused by bacteria transmitted to humans through bites from a single species of arachnid.

The creature in question is the tick, which bites humans in order to feed on their blood.

They hide in shady, moist, leaf litter, but also clings to tall grass, shrubs and low tree branches, waiting for an animal to brush against them so they can climb on board.

Ticks prefer dark crevices

Ticks can attach themselves almost anywhere on the body, but prefer creases like the armpit, groin, or back of knee.

In the US, where the disease is more common, the Borrelia burgdorferi bacteria causes the disease.

In the UK a related bacteria - Borrelia garinii - is predominant.

Over the weeks following infection, the disease manifests itself in a variety of symptoms, some of them severe.

The first of these is an expanding rash, or bruise, which starts at the bitemark, which can appear either as a single red blotch, or as a "bullseye"-shaped feature with a widening ring around the central point.

This can feel warm to the touch - but does not necessarily itch or hurt, and does not appear until at least a week after transmission has taken place.

When the rash appears, sufferers can also experience joint pains, fever and fatigue, and as the bacteria continues to spread around the body, other symptoms, including a stiff neck, facial paralysis or nerve tingling.

But the worst symptoms only occur some time after the tick bit, perhaps up to a year.

Joint pain and memory loss

These can include severe headaches, painful arthritis and joint swelling, heart problems and even mental disorders such as short term memory loss and difficulty concentrating.

If caught early, the disease is treatable with antibiotics - however, late stage Lyme disease does not respond as well.

Advice in America, where the numbers of Lyme disease cases run into hundreds of thousands annually, is that people should check themselves for bites on a regular basis.

Gardeners should wear light coloured gloves and clothing, and check it regularly for the dark ticks.

If you do find a tick, the chances of Lyme disease transmission are low if the tick can be removed quickly.

The best way to do it is to use tweezers and to pull directly outwards, not jerking or twisting, and then using antiseptic on the wound.