Hello, friends!  Welcome to this week’s episode of Sciency Words, a special series here on Planet Pailly where we talk about the definitions and etymologies of scientific terms.  Today’s Sciency Word is:

PANDEMIC

I normally write about space stuff.  Life on Mars, Pluto’s planet status… things like that.  But I thought I’d change things up a bit and talk about a medical science thing.  Why?  Oh, no particular reason.

In 1666, English physician Gideon Harvey wrote a book called Morbus Anglicus.  According to the Oxford English Dictionary, that book includes the earliest known usage of the word pandemic.

Pandemic comes from two Greek words meaning “all” and “people.”  For Gideon Harvey, it seems that pandemic diseases (leprosy, the bubonic plague, and most especially tuberculosis) are diseases that afflict all people, regardless of social status.  At least that’s my inference after reading the first chapter of Morbius Anglicus.

In modern usage, the meaning of the word pandemic has changed.  The World Health Organization (W.H.O.) and the Centers for Disease Control and Prevention (C.D.C.) use several different terms to categorize disease levels.  According to this online textbook from the C.D.C., those terms include:

• Endemic: a level of disease that is normal for a given population.
• Outbreak: a sharp increase above the endemic level of a disease within a geographically small area.
• Epidemic: a sharp increase above the endemic level of a disease within a geographically large area.
• Pandemic: an epidemic that is no longer geographically contained, i.e.: an epidemic that has crossed national borders or spread from one continent to another.

Those may seem like clear, straightforward definitions on paper, but according to several sources (like this one or this one or this one), that official definition for pandemic may be inadequate.  Lots of diseases cross national borders.  Lots of diseases hop from continent to continent.  The W.H.O. and the C.D.C. don’t issue pandemic alerts every time this happens.

The problem apparently came to a head in 2009 with the H1N1 swine flu.  Yes, swine flu was crossing borders, but public health officials started quibbling over whether swine flu was new enough or infectious enough or deadly enough to qualify for pandemic status.  Those qualifiers aren’t included in the official definition, but for a lot of people, it feels like they should be.  Otherwise, the seasonal flu would be a pandemic.

Now I’m not particularly well versed in medical science, so allow me to end this post by talking about a space thing.  In the early 2000’s, astronomers started arguing about whether Pluto was truly a planet.  This led to the International Astronomy Union issuing a new, more detailed definition of the word planet (and nobody had an argument about Pluto ever again).

Based on everything I read while researching this post, I feel like a similar story is unfolding over the word pandemic.  Perhaps, as scientists learn more about the spread of infectious diseases in our modern, globalized society, a new, more detailed definition for pandemic will emerge (and I’m sure it will be as universally accepted as the I.A.U.’s planet definition was).

Next time on Planet Pailly, it’s time to reveal my theme for this year’s A to Z Challenge.