Although the uninjured skin is germ-proof and it takes cutting instruments such as knives, needles and the boring tools of lice and itch mites, to penetrate it, still our minute enemies, bacteria and viruses, make many successful flank attacks on it. However they enter the body, they make plenty of trouble as they travel along, and in most cases the changes in the skin are the least important. Thus with spotted fever, as meningitis was formerly called, the infection of the brain is what raises havoc; and in scarlet fever, the effects on the heart and kidney can cause death. Fortunately, this disease has now become comparatively mild.
As the skin is wide open to observation, and nothing impresses us more than what we see, it is to be expected that a group of diseases with remarkable skin changes should be classified together. They were given the name exanthemata, a snappy word signifying “diseases blossoming out upon the skin.” These were of great importance long ago, their victims often being isolated in pest houses. In my medical school days patients with skin diseases of this type were often put in separate hospitals, although we no longer called them pest houses.
These diseases were all extremely contagious. I suppose that they are still just as contagious, but we know better now how to handle them. Smallpox is an example, once dreaded everywhere, now practically non-existent in the United States.