( ( A pathogen ) ( ( is ( ( a ( bacterium ( , ( ( virus or ) parasite ) ) ) ) ( that ( ( causes or ) ( is ( capable ( of ( causing disease ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NN pathogen)) (VP (VBZ is) (NP (NP (DT a) (NN bacterium) (, ,) (NN virus) (CC or) (NN parasite)) (SBAR (WHNP (WDT that)) (S (VP (VP (VBZ causes)) (CC or) (VP (VBZ is) (ADJP (JJ capable) (PP (IN of) (S (VP (VBG causing) (NP (NN disease)))))))))))) (. .)))
A pathogen is a bacterium, virus or parasite that causes or is capable of causing disease.
(ROOT (S (NP (NNS Pathogens)) (VP (VBZ is) (NP (NP (DT the) (NN term)) (PP (IN for) (NP (JJ disease-causing) (NNS agents))) (, ,) (PP (JJ such) (IN as) (NP (NNS bacteria) (CC and) (NNS viruses))))) (. .)))