IT is small and looks fairly harmless, but this little creature and his mates will be wreaking havoc on the health of up to 2,000 British country lovers this year.

This is Tick Alert Week, and experts are warning people to cover up and use insect repellent to avoid picking up an infection from one of the parasites when walking in the countryside this spring and summer. The New Forest is one of the high-risk areas.

The best-known tick-borne infection is Lyme disease, named after a small community in New England that experienced a cluster of cases in the mid-1970s.

Since 2003, the number of Lyme disease cases in Britain has risen from 292 to 684. It is usually transmitted via tiny deer ticks, with bacteria entering the bloodstream through the bite.

For around three-quarters of infected people, the first sign is a large red spot, usually on the thigh, buttock, trunk or armpit. The spot expands to a diameter of 6in (15cm), often with a central clearing. Nearly half of infected people go on to develop more, usually smaller, red areas.

Other symptoms can include fatigue, chills, fever, headaches, stiff neck, and pains in the muscles and joints. More rarely, sufferers can have backache, vomiting, sore throat, swollen lymph nodes and an enlarged spleen.

The symptoms can come and go, but the feeling of illness and fatigue may carry on for weeks. About 15 per cent of sufferers develop further complications, such as meningitis and heart disorders. Arthritis can appear up to two years after the first symptoms.

Elsewhere in Europe, up to 10,000 people a year develop tick-borne encephalitis, a severe infection of the brain that can lead to meningitis or even paralysis and death. The disease is now in 27 countries across the mainland continent, 11 more than in 2006. One in 30 cases is fatal.

Wendy Fox, chairman of the tick disease charity BADA-UK, said: "Because tick-borne diseases can produce a bewildering variety of signs and symptoms, they are difficult to diagnose.

"Ticks can be as small as a poppy seed and difficult to see. Their bites are painless and many people are unaware that they have been bitten. That is why it is very important to take the correct precautions."