Glandular Fever is bloody awful. Had it when I was 15 and got it 2 months before my GCSE exams. Missed all of the studying sessions, everything. Had to drag myself in to school to sit the exams, most of which I could barely stay awake for, a couple I ended up leaving early.
Shame no one informed me I could have had this taken into consideration on my grades! It's a really horrible thing to have, that sticks with you for a long time after you're well enough to return to society!