( ( Some deer ) ( ( carry ( ticks ( that ( may ( leave ( behind ( ( ( the ( Borrelia ( burgdorferi bacterium ) ) ) , ) ( which ( causes ( Lyme disease ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT Some) (NNS deer)) (VP (VBP carry) (NP (NP (NNS ticks)) (SBAR (WHNP (WDT that)) (S (VP (MD may) (VP (VB leave) (PP (IN behind) (NP (NP (DT the) (NNP Borrelia) (NN burgdorferi) (NN bacterium)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ causes) (NP (JJ Lyme) (NN disease))))))))))))) (. .)))
Some deer carry ticks that may leave behind the Borrelia burgdorferi bacterium, which causes Lyme disease.
(ROOT (S (NP (JJ Lyme) (NN disease)) (VP (VBZ is) (VP (VBN caused) (PP (IN by) (NP (NNS bacteria))))) (. .)))
Lyme disease is caused by bacteria.