There are some words you just gotta use even if they're awkward - they have a specific meaning, and you don't want any confusion on the issue. "Pandemic" is one of those words. A pandemic is when a disease meets four criteria:
- It can be transmitted to humans.
- It can be transmitted easily from human to human.
- Much of the human population is susceptible to it.
- It has a high death rate.
In other words, a pandemic happens when a disease spreads quickly and kills a lot of people. An epidemic is when there's more cases of a disease than expected for that time and place. An epidemic might involve a city; pandemics often involve countries. The 1918 flu spanned the entire globe, and it's usually used as the worst-case-scenario for the spread of modern diseases.
The 1918 flu is pretty interesting all on its own. You probably know someone that lived through it - ask them about it, read stories at the
PandemicFlu.gov archive, or check out the
National Archives. It is really depressing, though - anything that ends with mass graves is not going to be a happy story.
