Lyme's disease rash on the skin of a 28 year old female patient. Lyme disease is caused by the spirochete bacterium Borrelia burgdorferi, producing a rash, fever, and nerve and heart problems. The bacterium infects humans and animals, and is spread by ticks. The disease causes flu-like symptoms, arthritis, meningitis, and hallucinations. If diagnosed early it can be successfully treated with antibiotics.