Report.

  • South Africa. Tuberculosis Commission.
Date:
1914
Catalogue details

Licence: In copyright

Credit: Report. Source: Wellcome Collection.

Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.

    364/396 (page 342)
    It is generally admitted that, in the adnlt, the lung is the seat of election for tnl)ercnloiis processes, and perhaps owing to this it lias heeu assumed that in- fection must have taken place thro^^gh the respiratory passages. No such assump- tion as the latter is necessary. Any tuberculous centre, such, for instance, as a breaking down lymphatic gland, may infect the blood stream with tubercle bacilli, these being arrested in the fine capillary network in the lung. That infection through the blood stream must almost certainly be the route of infection, whether the bacillus gains an entrance by the alimentary canal or by tlie respiratory pas- sages, will be clear when we remember the physiology of respiration. The alveoli are aerated by a process of diffusion; no direct air current entering the alveolus. Any bacilli, therefore, carried through the trachea will get caught on the mucous membrane of the wall of the bronchi or larger bronchioles, or else be expelled by expiration. The ciliated epithelium of the bronchial mucous membrane tends to sweep the organism out of the lungs, not to drive them into the alveoli. But jU'imary tuberculosis of a bronchus is exceedingly rare, even if it occurs at all. The site of the earh' lesions in the lungs is iisually just under the viceral pleura, it would appear likely, then, that the organism must be conveyed to this site through the blood stream. Two portals of entry are, therefore, conceivable (oi) through the alimentarv mucous membrane (including the tonsils and salivary glands) to the mesenteric glands and abdominal organs and thence to the lungs, or (b) through a bronchus to the bronchial glands and so through the blood stream to the lung. In view of recent experimental observations and of the statistical evidence now before us in regard to native tuberculosis, it would seem probable that the former route is by far the more common. In the European in Europe, infection probably takes place in early childhood, at which period the lympliatic glands are physiologically more active, and therefore presumably a better protection. Assuming that the bacillus gains a footing in the child—and only a quiescent focus remains, when this at some later period serves as the centre from which a pulmonary infection starts, no sign of the route of original infection remains to be found. If, however, no chance of infection occurs until adult life—the period of greatest susceptibility—has been reached, and the patient succumbs to this infection, the portal of entry will pro- bably be more easily observed. From the evidence in regard to the result of Calmette's reaction in natives on their first trip to Johannesburg it is reasonable to suppose that man}' more escape infection in childhood than is the case among Europeans in Europe : and this may account for the large inimber of cases in which the nbdominal lesion is clearly the primary— that is to say, the older or more advanced, and also for the acute nature of so many of the cases. The hypothesis which I would suggest as best fitting the facts in regard to tuberculosis is this: Fatal cases of tuberculosis in adults in Europe are often due to auto-infection from some latent focus, acquired in youth or childhood through the alimentary canal. When infection has not occurred in childhood—as is pro- bably often the case amongst the tropical natives—the route of infection is usually evident at the post-mortem examination, and in the large majority of case is un- doubtedly alimentary. For physiological and bacteriological reasons it is diffi- cult to conceive how living bacilli can gain access to the alveolus except through the blood stream or lymphatics; if this i,s so, our views on the relative importance of air-borne and food-borne infection require considerable modification. The chief points raised in this paper may be summarised as follows: — (a) If pulmonaiy tuberculosis be an infectious disease—using the term as originally defined—we should expect undoubted evidence of marital infection to be forthcoming. We find, however, little or no evidence of its existence; and amo7ig,st the very poor and destitute where, if infection is a factor of importance it should be most marked—absolutely no evidence of its existence is found. (b) The correlation in regard to tuberculosis which is found to exist between children and parents cannot be explained by a theory of infection; an adequate -explanation is, however, provided by the theory of the iiilieritance of the tuber- culosis diathesis. (c) Just as we have failed to find any definite evidence of infection between husband and wife, or from parents to children; so we fail to find any evidence of the infectious nature of this di,sease from the histories of the institutions for tuber- culous patients. ((]) The common argument namely, that the falling death-rate from Tuberculosis in England is due to improved hygiene, the segregation of the tuberculous, and a recogjaition of the infectious nature of the disease, is not supported by the facts.