People going camping or walking on the North York Moors are being urged to take precautions to prevent them being bitten by ticks.
The Health Protection Agency said in 2008 there was an increase in cases of Lyme disease, a tick-borne infection.
It said the moors was one of several areas which tended to be more affected.
Wendy Fox, who was left paralysed after being diagnosed with Lyme disease in 1993, urged people not to take the subject lightly.
Lyme disease is an infection caused by a bacteria which is transmitted to humans by ticks that live on animals.
Most cases can be treated successfully with antibiotics but, if left untreated, it can infect the heart, joints and nervous system.
Mrs Fox, from Wath-upon-Dearne in South Yorkshire, was bitten by ticks while working as a zoo keeper and now spends her life in a wheelchair, paralysed from the waist down.
She founded the BADA-UK charity, which was set up to raise awareness of tick-borne diseases.
Mrs Fox told BBC News: "I think people do take the subject very lightly and it's frustrating for me and for us as a charity that people don't take them seriously.
"The problem is that one tick is all it takes to make you sick and if you can recognise the fact that they are there and take precautions against them that's so, so important."
The Health Protection Agency (HPA) said ticks were small and could easily be overlooked.
Professor Mike Catchpole, from the HPA, said: "Check for attached ticks regularly and remove them promptly. Most ticks do not carry the infection and infected ticks are very unlikely to transmit the organism if they are removed within a few hours of attachment.
"The most common symptom of Lyme disease is a slowly expanding rash which spreads out from a tick bite, usually becoming noticeable after about three to fourteen days."