Simplify the following text for a Grade 7 native English-speaking person.
Original: Although Allen Steere realized in 1978 that Lyme disease was a tick-borne disease , the cause of the disease remained a mystery until 1982 .
Simplified: Although Allen Steere realized Lyme disease was a tick-borne disease in 1978 , the cause of the disease remained a mystery until 1981 , when B. burgdorferi was identified by Willy Burgdorfer .