Lyme disease, also known as Lyme borreliosis, is a tick-borne illness caused by Borrelia bacteria. It is transmitted through the bite of infected blacklegged ticks (also known as deer ticks). Lyme disease is most common in the Northeast, mid-Atlantic, and upper Midwest regions of the United States. However, changing weather patterns are creating conditions for ticks to survive in more areas of the country. Cases of Lyme disease are on the rise; approximately 476,000 new cases occur in the U.S. each year.
The most common sign of Lyme disease is an expanding red rash known as erythema migrans (EM), which appears at the site of the tick bite about a week after. The rash is typically not itchy or painful and occurs in 70–80% of infected people. Other early symptoms include fever, headache, and fatigue. If left untreated, the infection can spread to the joints, heart, and nervous system, leading to issues like facial nerve paralysis, joint pain, and heart palpitations. Most cases of Lyme disease can be treated successfully with a few weeks of antibiotics, especially if caught early. However, some individuals may experience lingering symptoms like pain or fatigue, known as post-treatment Lyme disease syndrome (PTLDS).
