( ( Lyme disease ) ( ( is ( caused ( by ( ( a bacterium ) ( carried ( by ( infected ( deer ticks ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Lyme) (NN disease)) (VP (VBZ is) (VP (VBN caused) (PP (IN by) (NP (NP (DT a) (NN bacterium)) (VP (VBN carried) (PP (IN by) (NP (JJ infected) (NNS deer) (NNS ticks)))))))) (. .)))
Lyme disease is caused by a bacterium carried by infected deer ticks.
(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.