Final answer:
Lyme disease is caused by the spirilla bacteria of the genus Borrelia, specifically Borrelia burgdorferi, which are transmitted by infected Ixodes ticks.
Step-by-step explanation:
The type of bacteria that causes Lyme disease is known as spirilla. Specifically, the disease is caused by the spirochete Borrelia burgdorferi, which is transmitted to humans through the bite of an infected tick. The ticks that most commonly spread the bacteria are of the Ixodes species.
The classic symptom of Lyme disease is a "bull's eye" rash, but if left untreated, it can lead to more serious symptoms affecting the nervous system, joints, and heart.