membrane of the nose, mouth or tonsils into the neighbouring lymphatic glands, and thence through the blood or lymph Path of infection. into the lungs. (3) By ingestion of tubercle bacilli into the lower part of the gastrointestinal tract in the food; thence the bacilli may pass through the lining membrane, infect the neighbouring glands and pass by the blood or lymph stream to the lungs. (4) By penetration of other mucous membranes (such as the conjunctival or urogenital) or through the skin. (5) Possible, though very rare, placental infection.
Tubercle bacilli may not produce any anatomical lesion at the point of entrance, or they may remain latent for a very long time; and it has been experimentally proved that they may pass through mucous membranes and leave no trace of their progress. As reported to the Royal Commission, the introduction of bacilli into the alimentary canal is not necessarily followed by the development of tuberculosis. The writings of Von Behring have led to renewed attention being paid to intestinal infection, particularly through the milk supply. Von Behring suggests that the bacillus itself may become modified in the human body.
Measures for the prevention of tuberculosis may be divided into two classes: (1) general; (2) special. Great attention Prevention. has been paid to the latter since the infectious nature of the disease was established. The former include all means by which the conditions of life are improved among the mass of the people. The most important of these are probably housing and food supply. The reduction of the disease recorded in England is attributed to the great changes which have gradually taken place in such conditions since, say, 1850. Wages have been raised, food cheapened, housing improved, protection afforded in dangerous trades, air spaces provided, locomotion increased, the ground and the atmosphere have been cleaned and dried by sanitary means. In addition to these general measures is the provision of consumption hospitals, which act by segregating a certain amount of disease. Yet all these things, beneficial as they may be, do not wholly account for the reduction, for, if the records can be trusted, it was in progress before they had made any way or had even been begun. This observation, coupled with the apparently general tendency to diminution among civilized races, suggests the operation of some larger agency. The theory of acquired resistance, which has been already mentioned, would explain the diminution; and it is also in keeping with other facts, such as the great susceptibility of savage races, which have not been long exposed to tuberculosis, and the results of laboratory experiments in artificial immunity. The point is of great importance, and deserves careful attention; for if the theory be correct, the special measures for preventing tuberculosis, which are occupying so much attention, may eventually have unexpected results. Their general aim is the avoidance of infection, and they include (1) the provision of special institutions—hospitals, sanatoria and dispensaries; (2) the prevention of spitting; (3) the notification of consumption; (4) the administrative control of tuberculosis in animals; (5) the dissemination of popular knowledge concerning the nature of the disease.
The greatest stress is laid upon the prevention of spitting, because the germs are contained in the sputum of consumptive persons, and are scattered broadcast by expectoration. The sputum quickly dries, and the bacilli are blown about with the dust. There is no question that infection is so conveyed. The Manchester scientific experiments, mentioned above, are only one series out of many which prove the infectivity of dust in the proximity of consumptive persons, and they are confirmed by actual experience. Several cases are recorded of healthy persons having contracted the disease after occupying rooms in which consumptive persons had previously lived. It is a legitimate inference that spitting in public is an important means of disseminating tuberculosis, though it may be noticed that international prevalence by no means corresponds with this disgusting practice, which is a perfect curse in Great Britain, and far more common both there and in the United States than on the continent of Europe. Prohibition of spitting under a statutory penalty is attended with certain difficulties, as it is obviously impossible to make any distinction between tuberculous and other persons; but it has been applied in New York and elsewhere in America, and some local authorities in Great Britain have adopted by-laws to check the practice. Another means of controlling dangerous sputa is more practicable, and probably more effective, namely, the use of pocket spittoons by consumptive persons. Convenient patterns are available, and their use should always be insisted on, both in public and in private. The most effective way of destroying the sputa is by burning. For this purpose spittoons of papier mâché and of turf have been successfully used in the Vienna hospitals (Schrötter). When glass spittoons are used the contents can be sterilized by disinfectants and passed down the drain.
Notification is of great service as an aid to practical measures of prevention. It has been applied to that purpose with good results in several cities and states in America, and in some towns in Great Britain. New York has made the most systematic use of it. Voluntary notification was adopted there in 1894, and in 1897 it was made compulsory. The measures linked with it are the sanitary supervision of infected houses, the education of the people and the provision of hospitals. In England, Manchester has led the way. Voluntary notification was adopted there in 1899: it was at first limited to public institutions, but in 1900 private practitioners were invited to notify their cases, and they heartily responded. In Sheffield notification was made compulsory by a local act in 1904 for a limited period, and was found so valuable that the period was extended in 1910. The objects aimed at are to visit homes and instruct the household, to arrange and provide disinfection, to obtain information bearing on the modes of infection, to secure bacteriological examination of sputum, and to collect information to serve as a basis of hospital provision. Disinfection is carried out by stripping off paper, previously soaked with a solution of chlorinated lime (1½ oz. to the gallon), and washing the bare walls, ceiling, floor and everything washable with the same solution. This is found effective even in very dirty houses. In clean ones, where the patients have not been in the habit of spitting about the rooms, it is sufficient to rub the walls with bread-crumb and wash the rest with soap and water. Clothing, bedding, &c., are disinfected by steam. The advantages of these sanitary measures are obvious. Notification is no less important as a step towards the most advantageous use of hospitals and sanatoria by enabling a proper selection of patients to be made. It is compulsory throughout Norway, and is being adopted elsewhere, chiefly in the voluntary form. In 1908 the Prevention of Tuberculosis (Ireland) Act was passed, which conferred on local authorities the right to make notification compulsory in their districts, and provided that certain sections of the Public Health (Ireland) Act 1878 and the Infectious Diseases Prevention Act 1890 should apply to tuberculosis. By this act also the county councils were enabled to establish hospitals and dispensaries for the treatment of tuberculosis and were empowered to borrow money or levy a poor rate for the erection of sanatoria for the treatment of persons from their respective counties suffering from the disease.
The prevalence of tuberculosis in cattle is of importance from the point of view of prevention of the probability that abdominal tuberculosis, which is a very fatal form of the disease in young children, and has not diminished in prevalence like other forms, is caused by the ingestion of tuberculous milk. Whether it be so or not, it is obviously desirable that both meat and milk should not be tuberculous, if it can be prevented without undue interference with commercial interests. Preventive measures may be divided into two classes. They may deal merely with the sale of meat and milk, or they may aim at the suppression of bovine tuberculosis altogether. The former is a comparatively easy matter, and may be summed up in the words “ efficient inspection.” The latter is probably impracticable. If practicable,
