TUBERCULOSIS OF THE LUNGS.
Definition. — Pulmonary tuberculosis, phthisis, or consumption, is a specific in flammation of pulmonary tissue caused by the inception of the tubercle bacillus. Small nodules are scattered, more or less profusely, throughout the diseased areas, and cause certain pathological changes, such as infiltration, caseation, fibrosis, calcification, and ulceration.
There are three stages of this disease which may be recognized either patho logically or clinically, viz.: incipient, moderately advanced, and far advanced. There are also two varieties: the acute and chronic.
Etiology.—Prior to 1882 this disease was supposed to be hereditary, and little was known of its contagious character. In that year Koch revolutionized the accepted views of its etiology by demon strating the tubercle bacillus. This bacillus is one of the most prevalent of the known infectious germs. It attacks mostly the warm-blooded animals, being a common invader of fowls, pigs, cows, and other domestic animals; the horse is only slightly susceptible to infection. Some warm-blooded animals, notably the guinea-pig, while comparatively immune to infection, are very susceptible to ,in oculation.
Among the human race the disease is very easily contracted, and is the most wide-spread and fatal one to which man is heir. Its ravages are especially appar ent in large cities and towns.
Longitude and latitude have but slight influence upon its prevalence, but alti tude seems to exert a more or less con trolling influence upon the life of the germ. Foul air, overcrowding, lack of sunshine, dampness, combined with low altitude and unsanitary conditions gen erally, are all potent factors in the prop agation of the disease. Direct conta gion from kissing is possible, and the in ception of the germ may possibly occur through using the same eating and drinking utensils without careful sterili zation.
Infection by tuberculous meat eaten in a partially raw condition has been fre quently demonstrated, as well as the danger of infection by tainted milk. The latter is not an infrequent source of infection, and by many observers is ac countable for the prevalence of intes tinal and mesenteric tuberculosis in children.
Primary tuberculosis in a very large majority of cases begins in the lungs, and it is assumed that such cases are due to the inhalation of the bacillus in dried sputum in the form of dust. It is
claimed by some writers that prolonged exposure to the exhalations of tubercu lars in close rooms, as in crowded tene ments, is often followed by the develop ment of the disease. However, before this can be satisfactorily demonstrated, the very potent concomitants of unsani tary environment, constitutional dys crasia, and the lack of care in the dis posal of infected sputa must be elimi nated. After the crusade of 189G-97, in augurated by the Kew York Health Board, it was shown that secondary cases in given tenements or flats occurred in exact proportion to the intelligence and honesty displayed by the occupants in carrying out the prescribed rules for the disposal of sputa.
The bacillus may also be transmitted by a tubercular coughing directly at the face of a healthy person. Another method of transmitting the germ is the use of the "sanitary spit-cloths," which are subsequently burned with the secre tions which remain on them, no notice being taken of the pockets and the clothes constantly smeared by the mis named sanitary cloths wet with infected sputa.
Heredity as a causal factor of pul monary tuberculosis is to be noted only as a predisposing physical deformity which is inherited. This departure from the normal may be noted in a gen eral lack of resisting power to disease, especially a proneness to attacks of bronchitis; strumous conditions during childhood; abnormally narrow chests in a flat thorax and lack of expansion of the upper lobes of the lungs. A very significant indication of predisposition to pulmonary tuberculosis is a constantly present tachycardia. Certain forms of amemia are also etiological factors in the inception of this disease; poor food and prolonged lactation; employment in cer tain trades, such as knife-grinding and polishing; silk works, and mines are also to be noted among the general sources of pulmonary tuberculosis. Among other immediately predisposing factors may be mentioned pneumonia, influenza, bronchitis, pleurisy, syphilis, diabetes, and scarlatina.