Ticks

Hard-bodied (Ixodes) ticks are the primary Lyme disease vectors. In Europe, Ixodes ricinus, known commonly as the sheep tick, castor bean tick, or European castor bean tick is the transmitter. In North America, Ixodes scapularis (black-legged tick or deer tick) has been identified as the key to the disease's spread on the east coast, while on the west coast the primary vector is Ixodes pacificus (Western black-legged tick). Another possible vector is Amblyomma americanum (Lone Star tick),[9] which is found throughout the southeastern U.S. as far west as Texas, and increasingly in northeastern states as well.
The longer the duration of tick attachment, the greater the risk of disease transmission, but, typically, for the spirochaete to be transferred, the tick must be attached for a minimum of 12 hours, although, only the first part of this statement can be said to be strictly correct. (See Proper Removal of Ticks.) Unfortunately only 20% of persons infected with Lyme by the deer tick are aware of any tick bite,[10] making early detection difficult in the absence of a rash. Tick bites usually go unnoticed due to the small size of the tick in its nymphal stage, as well as tick secretions that prevent the host from feeling any itch or pain from the bite. New research suggests that transmission can occur within a few hours of tick attachment, and that the rate of transmission by infected ticks may be much higher than previously assumed.

-wikipedia