Pandemic - An increase in the occurrence of a particular disease over a very large region, such as a continent or the entire globe, that is greater than what is expected over a given period of time.⏎
Prion - A causative agent of infectious disease that is composed primarily of protein.⏎
Reservoir - An organism in which a parasite that is pathogenic for some other organism lives and reproduces without harming its host.⏎
Respiratory Tract - The part of the anatomy that has to do with the passage of air and includes the nose, larynx, trachea, and lungs.⏎