Prion - A causative agent of infectious disease that is composed primarily of protein.⏎
Pathogen - A biological agent that causes disease.⏎
Parasitism - A close relationship between two organisms in which one organism, the parasite, benefits at the expense of the host organism.⏎
Outbreak - An unexpected increase in the incidence of a particular disease over a given time period and geographic range. A general term that may refer either to an epidemic or a pandemic.⏎
Nanometer - A unit of length equal to one one-billionth (1 x 10-9) of a meter.⏎