Halloween, the time of ghouls, ghosts, and goblins, is nearly upon us.  So it might be time to consider the surprising amount of science that supports some of the most interesting Halloween myths.  

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For instance, Tuesday will find hordes of little Draculas trooping through neighborhoods seeking candy instead of their normal diet – blood.  According to movie legend, centuries-old Count Dracula needs to drink the blood of young people in order to remain immortal.  Surprisingly, in recent years a number of studies have reported that transfusing the blood of young mice into old mice actually does rejuvenate their hearts, brains, and muscles.  In fact, human trials of “young blood” to prevent diseases of aging are already underway.    

 

But I really want to talk about ghosts, many of whom will also be trooping through your neighborhood shortly.  I’m not talking about ghosts in the sheet-covered, transparent, from-beyond-the-grave, or candy-seeking sense.  I mean ghosts in the invisible-beings-with-the-power-to-do-you-great-harm sense -- what folks used to call “evil spirits.”   

 

Those ghosts can now be seen with the appropriate ghost detector, which is a good microscope.

 

Remember that for most of human history, sickness and death often struck haphazardly and without warning.  Your spouse, child, or uncle would be fine until one day they were struck by a fever or terrible diarrhea, took to their beds, and died shortly thereafter.  What else to blame but the spirit world?  Besides if you had any enemies in the village, you could blame them for calling up such spirits, and with enough support from your neighbors could schedule a nice witch-roasting for weekend entertainment.  

 

Before microscopes and other modern ghost detectors, we were at the mercy of our five senses.  If our food or water looked and smelled all right, it must be all right.   If a physician amputated a limb or treated an infection by drawing a few ounces of blood and the patient didn’t die right away, that must be all right too.  If the air smelled clean, it must be healthful.  Open windows were considered a boon to health.  It was well understood that foul odors were often associated with disease and the prevailing medical notion was that disease outbreaks were attributable to bad air.   

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Then French chemist Louis Pasteur came along and demonstrated beyond all doubt that everything -- air, earth, water, plants, animals, food, drink -- was awash with organisms invisible to the naked eye and undetectable by the nose, and that these “micro” organisms were not merely bystanders to the visible world, they often ruled it.  Micro-organisms caused our meat to rot, and our fruit and milk to spoil, and thankfully, for our wine to ferment, among other things. 

 

Pasteur also theorized that micro-organisms that don’t normally live inside us can cause diseases when they do manage to get inside our bodies.  The idea that germs cause disease is so well-established today that it is easy to forget what life was like prior to that discovery.  People dug latrines upstream from their drinking water supplies and commonly left food exposed to flies and other vermin around for days without refrigeration -- and still ate it.  Physicians would treat one patient after another -- or perform a surgery then an autopsy, then go back for another surgery -- using the same bloody hands and bloody instruments.  Washing hands and cleaning instruments between patients or procedures was not given a thought.  

 

To read the diaries of famous people prior to the discovery that germs caused diseases is to read a litany of chronic illness -- bouts of coughing, weakness, fever, or diarrhea that lasted for weeks or months, and often killed.  George Washington, for instance, suffered from a series of such near-fatal illnesses throughout his life.  They confined him to bed for weeks at a time in the years before he became our first President.  Such an infection, combined with the medical malpractice that was standard treatment at the time, did eventually kill him.  Such infections also killed his great grandfather and great grandmother, his grandfather and grandmother, his father, his father’s first wife, both his wife’s parents, a half-sister, a half-brother.  You get the idea.

 

As micro-organisms fill the air, some of them put there by coughing or sneezing sick people, the idea that bad air was the source of many diseases wasn’t completely crazy.  Airborne transmission of disease was responsible for some of our major scourges -- tuberculosis, smallpox, anthrax, flu, measles, and chickenpox, for instance.  But of course it wasn’t the air, it was the germs in the air that were at fault.  

 

Food- and waterborne diseases, such as E. coli-contaminated spinach or Salmonella-contaminated ice cream, that sicken, or even kill, a few dozen people make news headlines today.  They make headlines because they are rare events.  In 1850, they would have never been noticed against the massive background of such diseases that killed thousands of people every day.  

 

Pasteur taught us not only that ghosts cause disease, but that many of them could be killed by appropriate hygiene.  The first ghostbuster was soap and water.  Heat (pasteurization) or chemicals could also kill unseen germs.  By the early 20th century public water supplies were filtered and chemically-treated, making them much safer.  Freezing and refrigeration, thanks to the widespread availability of electricity, made stored food safer too.  By World War II we had developed drugs called antibiotics that killed the bacteria within us.  Surviving common infections due to food, water, air, or wounds became almost assured.  We had largely conquered our ghosts.  

 

So when your doorbell rings on Tuesday night and there in front of you stands a perfectly harmless ghost to whom you can hand some perfectly harmless candy, you might give a silent thanks to Louis Pasteur, the biggest ghostbuster of them all, and the man who probably has saved more lives than anyone in history.