Since You Asked: Epidemic, pandemic? What's the difference?

With swine flu in the news, health officials are tossing around words like epidemic and pandemic. Regular people I talk to aren't sure the difference between all these dire-sounding words for an outbreak of disease. Can the wordsmiths of Since You Asked help us out?

— Kris D., Medford

Fortunately, there are resources out there to help the wordsmiths of Since You Asked, and we are here to share the knowledge we find.

The Kaiser Family Foundation, which focuses on providing facts and analysis about health issues, has a journalists' toolbox online with a handy global health glossary.

It explains that "endemic" is the constant presence of a disease or infectious agent in a certain geographic area or population group. The common cold, for example, is endemic, especially among preschool pupils.

An "epidemic" is a rapid spread of a disease in a specific area or among a certain population group. Distemper epidemics periodically kill off many urban raccoons.

A "pandemic" is a worldwide epidemic or one that occurs over a wide geographic area and affects a large number of people or a high percentage of the population. The Spanish flu pandemic of 1918 affected an estimated 20 to 40 percent of the population worldwide.

Send questions to "Since You Asked," Mail Tribune Newsroom, P.O. Box 1108, Medford, OR 97501; by fax to 541-776-4376; or by e-mail to We're sorry, but the volume of questions received prevents us from answering all of them.

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