Lyme disease, also known as Lyme borreliosis, is a tick-borne illness caused by Borrelia bacteria, transmitted through the bite of infected ticks. It's the most common tick-borne disease in the Northern Hemisphere. In the United States, approximately 476,000 cases are estimated per year. Lyme disease is contracted via the bite of an infected black-legged tick. The infection is most common in the spring and early summer. Lyme disease has been reported in all 50 U.S. states and in at least 65 countries.
The most common sign of Lyme disease is an expanding red rash called erythema migrans (EM) that appears around a week after the tick bite. This rash is typically not itchy or painful and develops in 70-80% of infected individuals. Other early symptoms include fever, headache, and fatigue. If left untreated, Lyme disease can cause facial nerve paralysis, joint pain, severe headaches, heart palpitations, and other complications. Lyme disease is diagnosed based on symptoms, physical findings like the EM rash, a history of tick exposure, and blood tests. The infection is treatable with antibiotics, leading to a full recovery for most patients. However, some patients may experience long-term effects.
