>- a stunned pathogen doesn't ever really recover,
Very Very wrong! I have seen then zapped almost to the point of exploding, definitely stunned, but yet they later fully recovered, swam away, and reproduced.
That is the problem, she needed to microscopically observe that they were completely destroyed and she failed to do this, relying on the synchrometer instead.
I am not trying to be critical of her or her work, only that there are better methods of verifying successful destruction of parasites.