In the intervening years, Lyme disease has become the most notorious tick-borne illness in North America. The ticks that carry Lyme disease have expanded their range across the country. Cape Cod, Nantucket, Martha's Vineyard, Long Island, coastal areas of Rhode Island and Connecticut have experienced more cases of Lyme disease than most other areas of the Northeast and are referred to as highly endemic areas for this disease. The Lyme disease bacterium is carried by a tick generally known as the deer tick. It may pass the bacteria to a human or animal as it feeds upon them to obtain a blood meal.
Deer ticks have a three-stage life cycle.
The adult tick is smaller than the more common dog tick and is active in the fall and early spring while the larvae and nymphs are active during the late spring, early summer and fall. The nymphs are quite small, slightly larger than a sesame seed and can go unseen if not looked for closely. The larvae are extremely small, similar in size to the period at the end of a sentence. The deer tick may be carried by dogs and cats but the intermediate host animal is usually a white-footed mouse. Adult ticks feed and mate on deer and then drop off to lay eggs.