The statement that radiation sickness is not contagious is often found in the literature. That is true. The erroneous conclusion is drawn, however, that being around persons with radiation sickness is not dangerous. The danger arises from the manner in which radiation kills.
Sufficient radiation can cook the vital organs, but more often what happens is that it kills the white corpuscles and the ability of the bone marrow to make more of them. It is the white corpuscles that are the body's defenders against viruses, bacteria, and other disease causing bodies.
Once these defenders are lost the person succumbs to a disease they might have otherwise warded off, and once that disease takes hold in the individual they may become highly contagious.
In this manner there is grave danger of plagues breaking out, and all sorts of illnesses one does not generally see, becoming very threatening. For this reason rigorous quarantine, sanitary measures, and health defense measures must be imposed and enforced.
Becoming aware of such unexpected and unpleasant snares may initially make one feel that the situation is hopeless. The danger really arises from a person's unfamiliarity with the circumstances. There is the story of the explorer who asked the young native if there were crocodiles in a certain stream. He was assured there were not. While then swimming in the stream he once again saw the young lad on the bank and asked for reassurance that there were no crocodiles. "Oh no sir!", replied the shocked young fellow, "They won't come here. They are all afraid of the piranha."
The young fellow would have found himself equally in danger from things with which he was not familiar in our society, like automobiles and electrical appliances. It is not that the hazards are so onerous, but simply that we are not familiar with them.