Diphtheria, or malignant sore throat, has of late years come, unhappily, to be quite common, and is rightly much dreaded. The causative germ of the disease was discovered and de scribed by Loeffler, a pupil of Koch, in 1884, since which time it has been very widely studied, and has been found to do its damage by producing in the bodies of its victims, or even when growing in beef tea, a highly poison ous substance known as its toxin. Until 1892 no remedy for it was known, but in thAt year von Behring of Germany announced the dis covery of that remarkable antidote for the dis ease, now universally known as diphtheria anti toxin, Behring was led to his magnificent dis covery by reflecting upon the fact that some animals can be immunized to diphtheria toxin and that the blood of such immune ani mals is capable of neutralizing the poisonous character of the toxin produced by the germs of diphtheria. The manufacture of diphtheria antitoxin is now a large industry, sometimes carried on under private and sometimes under State or municipal control. There can be no question that its use has largely diminished the mortality from this disease.
There are many other diseases such as yel low fever, leprosy, scarlet fever, measles and pneumonia, a knowledge of which has of late years become more precise and practical, but these cannot be referred to within the limits of this article.
Some Methods for Health Improvement. — Engineering enterprises, such as drainage and sewerage, water supply, the filtration of water, the purification of sewage, the cleaning of streets, and garbage collection and disposal, have had much to do in the past, and will doubtless have much to do in the future, with improvement of the public health; and there is every reason to hope that the general death rate may continue to diminish, as it has dimin ished, in the past, largely by virtue of these enterprises. In addition, however, much re mains to be done; the more crowded sections of cities — the so-called slums— require the most careful supervision to prevent overcrowd ing, bad ventilation and accumulation of nox ious or even toxic wastes. The milk supplies of cities are as yet very largely in a primitive state so far as the production of milk is concerned, and it will become necessary in the near future either to improve radically the conditions of its production or else to abandon almost altogether the use of uncooked milk. Vegetables, fruits and berries, which are eaten in the raw state. such as celery, lettuce, radishes, watercress, cherries and strawberries are peculiarly ex posed to infection either by handling or because they are occasionally treated with manure-water during the process of growth, and such water is not infrequently polluted and infected. The dangers from oysters have already been re ferred to. How far uncooked or underdone
meats are dangerous is uncertain, although it is well known that uncooked ham and other lean meat of hogs has frequently caused trichinosis, an infection due to minute parasitic worms.
Illuminating gas, particularly water •gas, which contains a large percentage of carbonic oxide (CO), has an important bearing on the public health, not when Properly burned or by its products of combustion, but because of leaks in the mains or the service pipes, or about the fixtures by which it is distributed. Many deaths occur annually from this source, and the use of water gas should be accompanied by spe cial precautions.
As for the effect of Public gymnasia, play grounds and other open places in cities or other crowded communities little need be said, inas much as it is impossible to determine their precise value. There can be no question, how ever, as to the general wisdom or advantage of such things in modern cities. Isolation hospi tals for infectious diseases are gradually being established in our larger cities, and are filling a long-felt want. Best of all, the recent im provements in transportation are making it pos sible for large numbers of persons to live near, rather than within, cities and suburban life is becoming as characteristic a feature of modern life as is city life itself. Unfortunately this remedy for the evils of city life applies only to the fairly well-to-do, for the very poor will probably always find it easier, cheaper. and more exciting to live closely crowded in the congested centres of population, where work is most abundant and where the incidental diversions of a varied and noisy city life may be had free of cost.
The public health problem is very largely, but not exclusively, a problem of the life of crowded communities. Yet something needs to be said concerning the sanitation of farms which, while they ought to he the most health ful places in the world, are by no means always such. Damp or even wet cellars, bad ventila tion, overheating and poor feeding; defective sanitary arrangements, shaded houses and un wholesome surroundings, or close association with domestic animals, such as dogs, cats and poultry or swine, too often make farm life un sanitary, and boards of health having in charge the sanitation of States or Territories should give attention to these problems as well as to those of more crowded communities. Rail way sanitation, steamship .sanitation, and the more technical aspects of the work of boards of health, such as disinfection, scavenging, quaran tine, isolation, vaccination and the like, are nowadays subjects of great public consequence and are fully treated in . special works or memoirs, reference to some of which will be found at the end of this article.