Why is it called Lyme disease if the bacteria is Borrelia burgdorferi?

Lyme disease was named after the towns, Lyme and Old Lyme (Connecticut) where doctors from Yale first described the syndrome in 1975 after diagnosing several children that they thought had juvenile RA with Borrelia burgdorferi. Prior to that, infections with Borrelia burgdorferi were only believed to cause a rash.