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.⏎
National Institute of Allergy and Infectious Diseases (NIAID) - Part of the U.S. Department of Health and Human Services and the National Institutes of Health, NIAID conducts and supports basic and applied research to better understand, treat, and ultimately prevent infectious, immunologic, and allergic diseases.⏎
Prion - A causative agent of infectious disease that is composed primarily of protein.⏎
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.⏎