( ( 50 types ) ( ( cause ( disease ( in humans ) ) ) . ) )
(ROOT (S (NP (CD 50) (NNS types)) (VP (VBP cause) (NP (NP (NN disease)) (PP (IN in) (NP (NNS humans))))) (. .)))
50 types cause disease in humans.
(ROOT (S (NP (NP (JJ Protist) (NNS diseases)) (PP (IN in) (NP (NNS humans)))) (VP (VBP are) (VP (VBN caused) (PP (IN by) (NP (NN protozoa))))) (. .)))