My text book says Lyme Disease is a

bacterial illness. So,is Lyme disease
caused by a virus or a parasite?
I'm thinking its caused by a parasite.

Right. The ticks that carry the bacteria are parasites.

http://arthritis.webmd.com/tc/Lyme-Disease-Cause

Its a bacterial illness that is carried by ticks, they are the carriers not the cause

Lyme disease is actually caused by a bacteria called Borrelia burgdorferi, which is transmitted to humans through the bites of infected black-legged ticks. These ticks are considered parasites because they feed on the blood of animals, including humans, to survive and reproduce.

To find this information, you can refer to reliable sources such as textbooks, medical websites, or scientific research papers. In this case, you could refer to your textbook or consult reputable online sources like the Centers for Disease Control and Prevention (CDC) or the National Institutes of Health (NIH). These sources generally provide accurate and up-to-date information on various diseases, including Lyme disease.