Individual and Herd Immunity
Abstract
Individual and Herd Immunity SAGE Publications, Inc.1947DOI: 10.1177/001789694700500411 Maurice Mitman Joyce Green River Hospitals, Dartford INFECTIOUS diseases are due to invasion of the body by germs whose object is not to cause disease and death to the host, but to find facilities for living and multiplying themselves. Since pathogenic germs usually require living tissue on which to grow it is to their disadvantage to kill their host ; if as the result of their invasion the host dies, they usually die with him. From the germ's point of view, the most satisfactory arrangement is a state of parasitism in which the germs receive their sustenance without harming the host-indeed, sometimes helping the host's economy. Although knowledge of their contribution to the working ~ of the normal, healthy body is a relatively recent discovery, such organisms do exist in the intestine and this discovery has a bearing on the use of the marvellous new drugs, the sulphonamides and penicillin. These owe their great value to their ability to kill germs in the body without injury to the body. But sulphonamides, and to a much less extent penicillin, occasionally cause side-effects of an unpleasant character. For example, when given by