Besides the power of the tubercle bacilli to form tubercles and to cause cheesy degeneration, they are able to act as a true agent of inflammation and to cause exudative processes. It is true that this is exceptional, unless they have spread from their primary focus.
The spread of the germs may take place in many ways. In the majority of cases it occurs by contiguity; one tubercle forms next to the other, until they are all fused into a cheesy mass, forming the con glomerate or solitary tubercle. As an example of spread by contiguity we may cite tuberculosis of the intima of a vessel which, by contact, may form a tubercle on the intima of the opposite side (Fig. 136).
The second method of diffusion is by means of the body fluids, the secretions and the excretions. For example the urine may be the cause of development of tuberculosis of the bladder in a case of tuberculosis of the kidney. Or, again, one lymph-node may infect its neighbor, the bacilli being carried with the lymph-stream. Indeed, retrograde infection is conceivable in such a case if a node is so diseased that it offers a hindrance to the lymph-stream and causes stasis. In such a case, the bacilli would be carried against the lymph-current to lymph-nodes distally situated.
The third way in which tuberculosis may spread is by means of the blood. The bacilli may enter the blood in different ways: (1) the germs may at once enter the blood from the lymph and cause primary tubercu losis of the vessel wall. This may later give rise to a general miliary infec tion; (2) a tubercle in the neighborhood of the vessel may undergo degen eration and rupture through the vessel wall; (3) bacilli may find their way from the lymph-stream into the thoracic duct and thence into the venous blood, finding their way into the lungs and arterial circulation, In any of these three ways a genera] infection by tuberculosis may be brought about. However, in the case of tuberculosis by contiguity, and very often when the disease is spread by the excretions or secre tions, it may remain localized to a single organ or confined to a system of the body.
The peculiarities in the pathology of the disease which childhood exhibits are: very rapid growth; early degeneration of the tubercle; typical formation of miliary tubercles with giant cells, especially asso ciated with subacute miliary tuberculosis; frequent tuberculosis of the intima of the vessels; the predominance of gland, bone, joint, brain, and meningeal tuberculosis. Finally, and this is especially true of young
children, the frequency of generalization, and the rarity of signs of reaction in the surrounding tissues, which indicates the slight tendency towards healing.
Frequency.—Tuberculosis is a very frequent disease of childhood. The importance of this fact becomes more evident the longer one studies the subject of tuberculosis in children. However, the statistical basis for such an opinion is indeed scanty and contradictory in many particulars. In Vienna, Hamburger and Sluka found tuberculous lesions in 40 per cent. of the cases, agreeing with the figures of Schmorl in Dres den. The following table which they give, shows the frequency of tuberculosis in relation to the various ages: We may thus see that it is by no means rare to find tuberculosis in children, and that the nearer we approach puberty the oftener it is met with. The clinician must therefore look for tuberculosis in children of any age.
Diagnosis.—The diagnosis may be so evident that it can be made at a glance, or it may be attended with the greatest difficulties requiring the aid of all the resources at our command.
The history may give us an important clue. In every case we should learn whether either of the parents or grandparents had died of tuberculosis or hremoptysis, or whether numerous members of the family died at an early age. Such inquiry may prove negative and nevertheless we may be dealing with a case of tuberculosis. Tt may even happen that tuberculosis in the child discloses the fact that the par ents were afflicted with the disease. I could cite numerous cases where after finding definite signs in the offspring, a careful examination for the first time disclosed tuberculosis in the mother and father. Fur thermore we should enquire whether the child has come in contact with any one suffering from tuberculosis, even though it has been for only short periods (servants, midwives, teachers, etc.). Often tuber culosis is contracted from living with a tuberculous person for a short time, especially in the case of a child. Wassermann reports a case where an infant contracted a fatal infection as the result of living for only eight days with a person suffering from tuberculosis.