Invisible Enemy

Something is lurking
From deep inside
You cannot see it
And you can't hide

I got the power
To take you out
Resistance is useless
I hear you shout

The invisible enemy
We fight
We stand trial
The invisible enemy
How will this end?

Attacked in the morning
Dead by noon
You can’t see it coming
But you'll be dead soon

It's hard to breed now
It’s hard to see
Who could have done this?
Who's the enemy?