Typhoid fever, a diarrheeal disease, ever since its clear recognition, about 1840, as a mal ady distinct from typhus fever, has gradually come to be recognized as one of the most in sidious diseases of civilized societies. Its rav ages among the uncivilized are doubtless exces sive, and even among highly civilized societies it is far more frequent than it ought to be, ap parently because the bacilli which characterize and cause the disease are capable of maintaining their life outside the human body in the environ ment of man for a somewhat longer period and under somewhat more trying circumstances than are the germs of many other diseases. These bacilli are, for example, fairly resistant to cold and to dryness, and, although they are not known to produce spores, they are apparently able to persist for a long time (in greatly di minished numbers) in sewage, water, ice and upon fruits, vegetables and other articles of food. In milk under certain circumstances they may even multiply, and a very large number of epidemics of typhoid fever has been traced to infected milk. The same thing is true of drink ing-water, and, since 1894, when an extensive epidemic of this disease, due to infected oysters, occurred among the students and others in Wes leyan University, in Middletown, Conn., many investigations have been made, both in Europe and in America, tending to show that raw oysters are not infrequently grown near the mouths of sewers and that such oysters may readily convey the germs of this disease. Furthermore, since it has become known that the bacilli of typhoid fever occur not only in the bowel discharges, but also in the urine, and even in the sputum of persons sick of this dis ease, it has become easy to understand the fact that it is often really, as well as apparently, con tagious, although of course in far less degree than the eruptive diseases, such as smallpox, measles and scarlet fever. The control of ty phoid fever is now largely within our power, for it has been shown by experience, in armies and navies, that it can be mostly avoided by "vaccination" with a serum made from the dead bacilli of the disease itself.
Malaria awl ?malarial fever had long been associated in the popular mind with swamps, but until 1880 no germ characteristic of these diseases (which are really one and the same) had been discovered. In that year Laveran, French investigator in Algiers, discovered in the red blood-cells of persons sick of the disease certain animal parasites, protozoan in character, which appear to he not only the constant accom paniment, but the sufficient cause of the disease. Quite recently Ross in England, Celli in Italy and various other observers have proved beyond doubt that these germs are conveyed from one human being to another by means of certain female mosquitoes, belonging to the genus An opheles, without the bite of one of which con taining the microbes the disease does not ap pear to be transferable. The life history of these parasites has been worked out thoroughly, and to-day it is universally believed that malaria is caused by the parasites mentioned above, which spend only a portion of their normal life in their human host, and the remaining portion in the bodies of mosquitoes of the genus Anoph eles. The importance of this discovery can scarcely be overestimated, for although for merly, as already stated, malarial fever was as sociated with swamps, no one could tell pre cisely how; while to-day it is easy to see that if swamps contain infected malarial mosquitoes they may be dangerous sources of disease for human beings. On the other hand, it had long been observed that it was not swamps Per se which produced malaria, inasmuch as thousands of swamps had never been brought under sus picion. This circumstance is now interpreted
as due to the tact that whatever mosquitoes may have been present in the swamps in ques tion must have been of some other genus in capable of transmitting the disease; or else, if of the right genus, then these Anopheles had never become infected by biting human beings suffering with malaria. The practical import ance of these discoveries in regard to malaria cannot easily he exaggerated, for malarial fever has long been the dreaded pest of the engineer, and such enterprises as the digging of the Panama Canal had been enormously hampered and even prevented by the prevalence of malarial and other fevers. Nowadays it suffices to make sure that all sleeping huts or houses are covered with nettings which shall keep out mosquitoes, and that if possible the breeding places of these pests shall he either drained and altogether done away or else petrolized. that is treated with oil of some sort which shall inter fere with the breeding of mosquitoes.
Tuberculosis has long been recognized as one of the worst diseases afflicting the human race. It is characterized by certain cheesy masses called tubercles. which may be formed either in the lungs or upon the membranes of the brain, in the lymphatic glands or even within the tissues of the face, the disease in this last case being known as lupus (a wolf), and causing serious disfigurement. In 1882 Dr. Robert Koch discovered within these cheesy masses small microbic rods or bacilli to which he gave the name by which they are now uni versally known, of the Bacillus tuberculosis. These bacilli frequently occur in the sputum of tuberculous patients, and if this sputum is cast out upon the streets or in public places, it may become dried and disseminated in various ways, for example in dust. The bacilli arc believed to g of fine be disseminated also by the coughin moist particles from the lungs of tuberculous patients into the air; by milk derived from the tuberculous udders of tuberculous cows; by kissing—as when, for example, a tuberculous mother kisses her young child; by the hands,— as when a tuberculous patient, coughing upon his hand, afterward, without having washed it, touches the hand of another, or articles of food which are eaten raw; and in a great variety of other ways. Here also much is being done by boards of health and other sanitary organiza tions which seek to control the spitting nui sance; by physicians who educate tuberculous patients to use destructible spit-cups, handker chiefs and the like; by sanatoria, that is, estab lishments intended especially for the benefit and cure of cases of incipient tuberculosis, and by a campaign of education consisting largely in the distribution of literature bearing upon the disease. Among the most noted sanatoria for tuberculosis in the world are those at Davos Platz, in the Italian Alps, and at Saranac Lake, in the Adirondacks. More recently State sana toria have begun to be established, the first in America being that of the State of Massachu setts, at Rutland, Mass. It was formerly thought necessary for incipent tuberculous cases to he removed to Colorado or other high, dry localities, but to-day it is commonly felt that, however, desirable a removal of this kind may sometimes be, it is not always wise, and that the essentials of a good sanatorium (which are largely rest, fresh air and good feeding) may often be found near a large city, the first institution of this kind to be established (namely, the Sharon Sanatorium at Sharon, Mass. only 16 miles from Boston, upon a slight elevation and a dry, sandy soil) having proved eminently successful.