Random fact and a mini science lecture

by Janie Jones

Two hours.

That’s how long it takes to count 5,500,000 Borrelia burgdorferi, which are the microscopic bacteria that cause Lyme disease.

Being microscopic, you need to view them under a magnification of at least 400 times and even still they look like wispy, kinky fine hairs.  For the super curious, they are only about 0.2-0.3 micrometers in diameter and can be up to 20 micrometers long.

They look sort of like this:

borrelia edit

I don’t know the magnification of this image I stole from Google images, but they look bigger in this photo than they do on the scope I use in the lab, so I’m guessing this is in excess of 400 x magnification.

Now, if you’ve never worked with microscopic stuff before, you might wonder how do you count 5 and a half million of some uber-tiny critter?

Well, you don’t actually count them one by one.  That would be crazy and nigh impossible.  You use science math.  And, a special slide called a Petroff-Hausser Counting Chamber.  It was actually made for counting sperm, but works for any super tiny microscopic thing.  It looks vaguely like this this photo I also stole from Google images:

petroff hauser

You place 5 microliters of your sample (sometimes you even dilute that, because a lot of microscopic critters can be suspended in even just 5 microliters), on the slide.  It has microscopic grid lines on it.  Then you count all the Borrelia in the grid.  Using science math you can then calculate how many of these guys you would have in a milliliter.  It actually is pretty easy.

What took so long is that I had to count nine different samples.  Which means not only did I have to count the little buggers nine different times, but I had to prepare 9 dilutions, and clean the slide between each sample.

I’ll be doing this a lot.  Maybe I’ll get faster.

Or maybe I’ll go cross-eyed.

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