THE SANITARIAN. JUNE, 1903. NUMBER 403. PREVENTABLE RESPIRATORY DISEASES.* By J. O. COвé, M.D., Surgeon U. S. Public Health and Marine Hospital Service. PNEUMONIA. It is only in late years that this disease has been generally recognized as one belonging to the infectious group. All kinds of conceivable theories have been advanced to account for it being so widely disseminated. Even at the present date few will believe that the effect of cold (as such) is not in itself the sole cause for pneumonia, but one will be more apt to accept the theory of infectiousness if told that there is as much, if not more, pneumonia in temperate climates than in the extreme cold of the Northern States or of Canada. Such, however, is a fact. Because of the exposed condition of the lung to the vicissitudes of weather, and noting that the majority of attacks come on during the winter months, we long labored under the delusion that sudden. exposure to cold and dampness were the sole etiologic factors in producing the disease. It will be attempted to present sufficient evidence to prove the position maintained by several writers that exposure to cold or cold and dampness are merely incidental and remote factors. That it is caused by the pneumococcus is as nearly certain as the skill of careful experimentation will allow. The exposure theory has been severely attacked by many on purely clinical grounds and by none more logically than Woods Hutchinson when he pointed out that— "Fatal lung diseases in any given race or class, particularly of tuberculosis and pneumonia, are in exactly inverse ratio to the amount of exposure to all sorts of climatic vicissitudes. Diseases Concluded from page 410. of the lungs are emphatically diseases of city dwellers. ("Human and Comparative Pathology.") His position is undoubtedly correct whether applied to man or bovines, and to make it more emphatic in reference to man, attention is directed to the mortality lists of certain cities and States. It is emphasized that pneumonia is a disease of overcrowding and not due merely to cold or exposure to cold or to constant living in dampness or a damp climate. One will be astonished to find that statistics show that in the cold of the north, where the exposure must be severe, there is - no greater ratio of fatality from pneumonia in a given number of population than in the milder climates further south, if the environment conditions are the same. That the percentage of deaths in a given number of cases of pneumonia is very much higher in the north during the extreme winter months there is not the slightest question. This I believe to be due rather to the heightened virulency and greater numerical dosage of the infecting organism at this time than to the cold per se. Knowing that there is a greater percentage of recoveries from the disease in the south, it is probably true that there are more cases to a given population than in the north. I have no way of ascertaining these figures, however, as the reported death rates are the only figures at hand. It is quite true that nearly all the cases of pneumonia occur in the three winter months of January, February and March. But this is true of influenza also, and the explanation of one will probably apply to the other. For whatever be the cause it would also explain the greater frequency of nearly all the acute infections, especially of smallpox. Neither pneumonia nor tuberculosis is due merely to the greater degree of cold. I would seek the explanation for pneumonia and influenza in these months to the greater dosage of the contagium due to the overcrowding and overheating that one sees in theatres, street cars and other shut-up, stuffy places where the heat is great enough to desiccate the germs of these diseases which have been planted in such places, mostly by coughing and spitting. Fresh air and ventilation stop all of them promptly. If contracting a "cold" is the sine qua non for an attack of pneumonia, we should have the greatest number of cases in the fall and spring, for it is then certainly that we have a greater frequency of chilling of the body. Auto-infection in pneumonia, directly into the lungs from the mouth and pharynx, is extremely doubtful. It is probable that the pneumococcus is first ejected by the saliva in spitting, and, having dried, enters the lungs in dust, and this is what happens in overcrowding in our city lives. The following mortality table was compiled principally from the census figures of registration cities and States: Illinois (outside Chicago)........ 3.122.975 1,094,521 The question of influence of cold and crowding is very noticeable if the figures for the smaller and newer towns where there is little overcrowding are taken in comparison with large cities in the same localities. For example, take Boston and Worcester. In 1900, in Boston, with its overcrowding, there were 24.98 deaths from pneumonia to every ten thousand inhabitants, while in Worcester there were only 16.12. Making the parallel more remarkable, take Albany, with 17.74 to ten thousand, and we have Atlanta, with practically the same population, with 21 to ten thousand. In comparing the States it was found that in those that are sparsely settled there is little pneumonia. This is true whether north or south. Minnesota for the last ten years had an average of six deaths for each ten thousand population, a very small rate for pneumonia in a very severe climate. Even California and Louisiana are greater, with 9.54 and 11.38, respectively. Taking Chicago out of the calculation of Illinois it was found that that would make the population condition about the same as Indiana, and the percentage of deaths in these States is then practically the same, while Georgia, with a little less population than Indiana, has practically the same number of deaths from pneumonia. There can be no doubt that this disease is one of city life rather than life in the country. It is the disease of segregation, not of isolation, and it would seem to be a disease of overcrowding rather than exposure to cold; hunger, cold and alcoholism being merely agents that favor the disease and apparently influence its mortality. Bacteriology. The disease is undoubtedly caused by Sternberg's organism, the pneumococcus. As far back as 1880 he called attention to this organism, which he had found in his own saliva. Experimentation led him to believe that it was the organism of specificity in pneumonia, and he published this fact in 1885. There is no doubt of his priority of discovery as to the organism itself and its actual and causal relation to pathology, and it is only fair that this honor be accorded him. Incubative Period.-We have no way of ascertaining or even guessing as to the incubative period in man. There is one point just here that is necessary to mention and which has been referred to before, viz.: There is often well-pronounced prodromata, followed by chill and fever, and the most careful clinician is absolutely unable to detect the lung lesion by his ear, notwithstanding he may be on the qui vive for pneumonia from the very start. And "yet there must be a condition antecedent to these changes that' constitutes the so-called 'first stage,' for which there is no anatomical indication." (Sturgis and Coupland. Quoted by Smith.) Here is certainly a colony of pneumococci growing on a respiratory mucous membrane, in this instance well down deep in the air vesicle itself. So far as our senses are concerned it is an invisible colony, undergoing the first phase of its growth, its second phase being the rapidly developed colony, causing an abundant outpouring of exudate, which, overflowing like a fermenting vat from one vesicle to another, speedily infects the entire lobe. The lung is the only organ of the body which is favorable for the growth of this organism. It grows on the meninges and in joints, though the change in media causes considerable change in its pathology and its exudate. An interesting peculiarity is that, while the organism may grow and multiply in the blood, on the meninges and in joints, it will not cause pneumonia when injected under the skin or into the joints or meninges or into the blood. It seems to be necessary for it to be implanted directly on the lung mucous membrane, for while it is constantly present in the saliva and nasal mucus, it does not become pathogenic until it reaches the air vesicles, where it finds the proper medium. And another exceedingly queer thing is that while the organism multiplies on the upper respiratory tract as a mucous membrane parasite and causes no harm, it produces one of the most fatal of diseases if successfully planted in the air vesicle. Here we have an example of the wonderful effect the slightest change in the medium will make in the specificity of certain organisms. Chief Sources of Infection.-It has been known for years that the common habitat, and the only known habitat, of the pneumococcus was the saliva and mucus of the upper respiratory tract. Sternberg discovered the organism in his own saliva, and it is commonly present in the mouths of most persons. It is also found on the nasal and pharyngeal mucous membranes of many people. There has been much speculation over the modus operandi of infection. It hardly seems reasonable that the organism reaches. the lungs by extension. It lives solely as an obligatory mucous membrane parasite in animal mucus, and so far as we know it is not facultative and will not grow in accidental media outside of the animal organism. It is more than likely that to be able for it to reach its destination of a field which furnishes the exact nutritive formula (the lungs) it must be ejected from the body in saliva or sputum and be desiccated. Then when re-introduced and planted on the delicate membrane of the air vesicle, other conditions being favorable, it will grow and multiply and produce the characteristic lesions of the disease. The animal condition necessary to incubate the organism when planted is anything that will lower the vitality either temporarily or continually. A sudden accidental plunge into water, or getting drenched in a cold rain, or exposure to severe snowstorms, excite the necessary cultural conditions for the growth of the organism, but, no organism, no pneumonia that's certain! It is a well-established clinical observation that the transitional stage from a nasal or bronchial catarrh is not an antecedent to pneumonia. The clinician is challenged to establish his first and preceding symptom as a "bad cold." The onset is more or less |