Autoimmune Disorder

During the 1918 pandemic, in the first wave of influenza, a preponderance of young healthy people died because of an over-reaction of the immune system.  Inflammation is a variable response mechanism the body uses to swell tissues with blood and interstitial fluid making each cell a citadel via osmotic pressure.  This is the perfectly designed response to a bug bite, walling off a foreign protein from spreading.  But swelling of the lung tissue is a dangerous strategy that cuts off oxygen.  Evolution taught our immune system the proper response.