I Caught A Bug

In my youth,
When I felt sick...
The cause was A Bug...
I caught A Bug.
No matter what, 
I came down with A Bug.
Now we know it's not as simple 
As just A Bug,
But some other wee carrier of woe...
Bacterial, viral, fungal, 
Or something so micro 
As an altered gene in your DNA,
That needs a bit of editing...
Which sounds as simple as punctuation,
But surely isn't. 
    And my old catchphrases being hard to change,
    I'll still say with a knowing shrug...
    When I'm under the weather...
    I caught A Bug