(S (S (BASENP (NNP CCD)) (VP (MD may) (VP (VB be) (VP (VBN caused) (PP (IN by) (NP (NP (BASENP (NNS mites)) (CC or) (BASENP (JJ associated) (NNS diseases))) (CC or) (BASENP (JJ unknown) (NNS pathogens)))))))) (PERIOD .))