URBANA, Ill. – For most of us, the flu is just the flu. We suffer through it for several days, and eventually bounce back. But for patients with multiple sclerosis (MS) and other neurological diseases, the flu can trigger a cascade of immune responses that result in a full-blown relapse of the disease. In a recent study from the University of Illinois, researchers shed light on what may be happening in the brains of MS patients during upper respiratory infections.