Sunday, December 30, 2012

Do People Really Not Know This?

A cousin of mine just posted an urban legend to her Facebook status. I first encountered this bit of misinformation 4 or 5 years ago, and was startled that anyone found it convincing:

In 1919 when the flu killed 40 million people there was this Doctor that visited the many farmers to see if he could help them combat the flu...
Many of the farmers and their families had contracted it and many died.
The doctor came upon this one farmer and to his surprise, everyone was very healthy. When the doctor asked what the farmer was doing that was different the wife replied that she had placed an unpeeled onion in a dish in the rooms of the home, (probably only two rooms back then). The doctor couldn't believe it and asked if he could have one of the onions and place it under the microscope. She gave him one and when he did this, he did find the flu virus in the onion. It obviously absorbed the bacteria, therefore, keeping the family healthy.

What jumped out at me back when I first heard this story was the country doctor examining the onion under a microscope and finding the flu virus (which did not mysteriously become a bacteria in the next sentence in the first version I heard.) Way back in high school, some fifty years ago, I remembered learning that a virus is too small to be observed with a regular microscope, and couldn’t be seen until the invention of the electron microscope. I can’t say that I recalled offhand when the electron microscope was invented, but 1919 sounded much too early, and even if labs had them in 1919, it would have been an exotic piece of equipment for a country doctor to have at his disposal.

So I did some Googling and discovered that the first electron microscopes weren’t available until the 1930’s, and they stood several feet high. Furthermore, it is only recently that an electron microscope that can be plugged into an ordinary household outlet has become available to the public - for $60,000. I don’t know what kind of outlet the standard electron microscope requires, but I’m pretty certain that there were country doctors back in 1919 who didn’t even have electricity.

I pointed this out (privately) to the co-worker who had sent us all the email revealing this interesting piece of information, which didn’t stop her from passing on other unlikely urban legends.

This time I decided to do a little more Googling. It turns out although in 1919 it was beginning to be known that flu was caused by a virus, it wasn’t until 1931 that Richard Swope found the family of  viruses that caused flu in pigs, and not until 1933 that the virus that causes human flu was isolated by Patrick Laidlaw. Our country doctor working in 1919 wouldn’t even have known what a flu virus would look like, and might not even have known that flu was caused by a virus and not by Bacillus influenzae (now known as Haemophilus influenzae), an opportunistic pathogen that usually is harmless until another infection (like the flu) gives it its opportunity to multiply. 

Now as I have pointed out, I did not learn all of this in high school, and wouldn’t have remembered it if I had, but I did retain that fact that a virus is really, really, itty-bitty, and can’t be seen in the kind of microscope we had in our school lab. It doesn’t take more awareness than that to see the holes in the onion story. Of course, as my son pointed out, even if the onion did absorb flu virus, it’s unlikely it could absorb enough to prevent humans from getting their share. Not to mention that if onions were this efficacious at preventing flu, doctors and medical journals might think to mention it.

I did not bother to correct my cousin. She has been going through a stressful time lately and a know-it-all post from her cousin is not needed. I just find myself wondering when I see someone fall for an urban legend like this, why they believe it. Almost always there is something in the story that sounds off, like the doctor being able to see a virus with an ordinary light microscope. 

There is something else I remember from my high school days, the question, “Says who?” I wish people would use it before passing improbable tales on to me.


  1. You don't need to know anything about electron microscopes or the flu virus though. Since having even one unpeeled onion in your house is enough to trap all of the flu virus, how could the flu ever become an epidemic? I would assume that most farmers have at least one onion nearby, at least around flu season. Why didn't those onions save anyone else?

    1. Also, you should never eat an onion you left in the fridge for a couple of days. Who knows what kind of crap it's been absorbing. In fact, why don't more people die of onion poisoning if onions are such effective germ traps?

  2. Hi, I'm dropping after following a link from Slacktivist.

    And speaking of urban legends and epidemiology... a long, long time ago, as the final project in a course on computer simulation theory, I wrote a program to simulate the spread of false rumors through a population. It was basically an epidemiological analysis, but instead of variables for virulence and incubation period and herd immunity, values could be set for things like "probability that a person hearing this rumor will believe it", "probability that a person who believes it will share it with others", and "probability that a person will bother setting a believer straight when told a rumor they know to be false".

    That last one turned out to be a surprisingly sensitive variable. I ran simulations in which increasing the population of debunkers by a tiny fraction of one percent made the difference between a lie being universally accepted or eventually dying out.

    Which is why I'm usually willing to be the jerk who posts the know-it-all corrections when people have been misinformed. A lie can be halfway around the world before the truth gets its boots on, as Mark Twain didn't actually say, and helping the truth with its laces can actually make a difference.

  3. Hi, Evan, that sounds like it was a great idea for a computer simulation. I hope you got a good grade.

    Jamha, that was a good point, although maybe people who believe urban legends like this don't realize that in 1919 people weren't keeping their onions in the crisper drawer of a refrigerator. I think the rule was you needed an onion in each room, though. Either way, it's not like an onion is some exotic piece of vegetation, so you're right.

    Aaron, the version of the rumor my cousin posted (not the one I linked to, but the one I quoted from) did go on to say that you must never used chopped onions that are more than a few hours old because they will be full of germs, and that onions, not mayonnaise, are to blame when potato salad goes bad. See link here:

  4. Rule of thumb: when a surprising, counterintuitive story like this one does not contain any specific information such as names, dates, and locations, it's false. If it *does* contain names, dates, and locations, the most likely reason is that it was fabricated by a slightly less lazy liar than the one who originated this bit of nonsense.

  5. Sounds like the miasma theory of flu is making a comeback!

  6. It seems to me that one of the reasons these kinds of urban legends continue to be welcomed is because they show "the common man" having more sense, better methods, better outcomes than the urbanized and technologically sophisticated "Doctors." It is part of the American anti-intellectualism. We see it rampant in much of our political debate. In the last election it went so far as to argue that the polling showing the President leading MUST be wrong because our common sense told us that Mitt Romney was more popular.

  7. What is it with urban legends reappearing? Someone in my circle was just saying to everyone "Have you heard the news that now you've gotta check your toilet seat for this itty bitty poisonous spider, seriously, some woman got bit in an Olive Garden restroom and..." I suggested checking that on out on Snopes, but she protested, "No, this was really recent news!" Really? What newspaper published the article? "I forget. Someone posted it to Facebook, though."

    If you do a search on "Olive Garden" at, the fifth hit is "Two-Striped Telamonia Spider", collected via email, circa 1999.