the cause is thought to be a combination of sweat, cold air, sharing water/vicks inhalers, and ingesting large amounts of e or whatever one likes to fly on.
sometimes thought to be the result of a minor overdose or vigorous e-fueled making out.
raver 2: "he's got the raver flu"
raver: "aw, so does bones, she's had it since kandieland.."
raver 2: "probably all that K and the 'rolling coaster' "
raver: "mm. want a blue lady?"
raver 2: "sure, let's share water."