Lyme Borreliosis Complex, commonly referred to as Lyme Disease, is an inflammatory disease often characterized at first by a rash, headache, fever, and chills, and later by possible arthritis and neurological and cardiac disorders. It is caused by Borrelia burgdorferi, a type of spirochete bacteria that is transmitted by ticks. A spirochete \ ˈspī-rə-ˌkēt  \ is a type of slender spirally undulating bacteria. Borrelia burgdorferi exists in North America and Europe. Until 2016, it was the only known cause of Lyme Borreliosis Complex in North America. Recently, Borrelia mayonii, discovered in the midwestern United States, has also been discovered to cause Lyme Borreliosis Complex. 

Dr. Jemsek coined the term Lyme Borreliosis Complex to describe what is commonly called Lyme Disease. If left untreated, Lyme Borreliosis Complex can progress to advanced stages, known as Chronic Lyme.