It's a letter.  The top half is missing.  The remaining says...

Yes, I'm infected.
I did everything I could, but I could only delay the progress by a few days.
The most frightening thing is, that I forget more about you by the day.

So I chose a peaceful death, rather than becoming the living dead.
Within an hour, I will have entered my eternal sleep.  I do hope you'll understand my decision...

Good Bye and Forever Yours,

                                            Martin Crackhorn