The investigators will recruit 100 PD patients and 100 control subjects. The investigators will characterize all subjects carefully with respect to clinical symptoms. The investigators will collect bacterial samples from the nose, mouth and stool of these subjects. Using modern genomic techniques the investigators will read out the genetic code of all bacteria contained in these samples and will be able to identify which species of bacteria are present in the samples. Using complex cluster computing the investigators will compare the pattern of bacterial species between PD patients and controls and look for specific abnormalities in PD patients.