The alarm clock goes off and you’re feeling a bit feverish and light-headed. Do you:

  • A) call work to tell them you need a sick day, or
  • B) get up, go in, and get the job done?

Before you answer, consider that your symptoms may be indications of an infectious illness. An illness that — if spread to your co-workers, who bring it home to their spouses, who also ignore their symptoms and spread it to their workplaces — could result in millions in lost revenue, businesses ruined, economies humbled, whole cities crumbling…

Just think about how much more light-headed you’d feel after that.

Presenteeism”, a culture of braving the workplace even when ill, is on the rise. Seven out of 10 Americans report that they go into work even when feeling sick and studies in Britain and Canada show similarly startling numbers. And the costs are staggering: A 2003 study found that presenteeism drains $160 billion from the US economy.

But in case you need more proof that such office martyrdom is unwise, check out this list of the most devastating viral outbreaks traced back to the workplace.

And then, please, just call in sick.

1. Massachusetts Measles
In 2006, over 1,000 employees of a major Boston financial institution were affected after one measles-infected worker — a contract employee from Asia who hadn’t received the standard vaccinations — carried the virus into the workplace.

The Department of Health ultimately ordered anyone who couldn’t produce documentation of vaccinations to stay at home for three weeks. The firm ultimately had to organize and distribute 12,000 doses of measles vaccines to 31 separate communities at a cost of a quarter-million dollars. And that figure doesn’t factor in all the productivity losses.

2. Bed-Bug Mania
Those small, wingless, rust-colored insects went on an absolute tear in the U.S. in the summer of 2010. And unlucky apartment dwellers weren’t the only victims — nearly one in five exterminators found bedbugs in office buildings that year, a startling spike from the less than one percent who found them in 2007.

Companies in big cities were particularly hard hit. In New York City, workplaces like Google, Elle Magazine, and the United Nations were forced to temporarily shut their doors because of infestations, prompting the city to set up a bed-bug advisory board and giving rise to the infamous workplace adage: “Skin rash shaped like a line? Staying home is just fine!”

3. Exchanging Futures, Exchanging Germs
In the fall of 1987, 116 employees at three Chicago futures exchanges came down with the mumps. Three of those cases led to home infections, and nine people ended up in the hospital, costing the exchanges over 700 lost working days. Considering what futures traders make, that’s a lot of money lost out on the trading floor.

4. Mock Outbreak
Last year scientists at the University of Arizona stumbled upon a shocking finding: When even one person shows up to an office sick, more than half of the commonly touched surfaces in that office become infected with the virus by lunchtime.

That’s according to a study they ran at an unnamed company, where the scientists placed liquid droplets on the hands of 80 employees and while most of the droplets were just plain water, one person unknowingly received a droplet containing an artificial virus. The workers went along with their normal workday, and within four hours, scientists discovered that more than half of the office’s communal surfaces had traces of the artificial virus.

“We were actually quite surprised by how effectively everything spread,” said one of the study’s authors. Well…we’re actually quite horrified now.

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