Lyme disease is caused by a bacterium which is transmitted to a person through the bite of an infected deer tick. Symptoms of Lyme disease include the formation of a characteristic expanding rash 3-30 days after a tick bite. This rash occurs in approximately 70- 80% of patients nationally. In Maine, the rash is reported in just over 50% of patients. Fever, headache, joint and muscle pains, and fatigue are also common during the first several weeks. Later features of Lyme disease can include arthritis in one or more joints (often the knee), Bell's palsy and other cranial nerve palsies, meningitis, and carditis. Lyme disease is rarely, if ever, fatal. Learn more about and how to prevent Lyme disease below.