( Trichomoniasis ( ( is ( caused ( by ( ( a protozoan ) ( called ( Trichomonas vaginalis ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Trichomoniasis)) (VP (VBZ is) (VP (VBN caused) (PP (IN by) (NP (NP (DT a) (NN protozoan)) (VP (VBN called) (NP (NNP Trichomonas) (NNS vaginalis))))))) (. .)))
Trichomoniasis is caused by a protozoan called Trichomonas vaginalis.
(ROOT (S (NP (NNS Trichomoniasis)) (VP (VBZ is) (VP (VB cause) (PP (IN by) (NP (DT a) (NN protozoa))))) (. .)))