Lyme disease, also known as Lyme borreliosis, is an infectious disease caused by the Borrelia bacterium It has 52 known species, and is spread by ticks.
Lyme disease is transmitted to humans by the bites of infected ticks of the genus Ixodes. In North America, mainly Borrelia burgdorferi and Borrelia mayonii are causes. Europe and Asia, the bacteria Borrelia afzelii and Borrelia garinii are also main causes of the disease.
The most common sign of infection is an expanding area of redness on the skin, known as erythema migrans, that appears at the site of the tick bite about a week after it occurred. The rash is typically neither itchy nor painful. Approximately 70–80% of infected people develop a rash. Other early symptoms may include fever, headache and tiredness. If untreated, symptoms may include loss of the ability to move one or both sides of the face, joint pains, severe headaches with neck stiffness, or heart palpitations, among others.