Age incidence in zymotic diseases / by John Brownlee.

  • Brownlee, John, 1868-1927.
Date:
1904
Catalogue details

Licence: In copyright

Credit: Age incidence in zymotic diseases / by John Brownlee. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    limit undefined is so great, and the difference of the number of cases at high ages given by the two assumptions is so very minute, that I have not hesitated to chiefly use the latter. It is found by trial that the age distribution follows this theoretical grouping very closely when diseases are considered which chiefly affect adults ] thus, enteric fever, typhus fever, and smallpox in vaccinated persons, show a very marked correspondence between the theoretical and the actual distribution of cases. Prof. Pearson has fully discussed the case of enteric fever. He takes the statistics of 8,689 cases of this fever treated by the Metropolitan Asylums Board Hospitals. Tlie fit of the theoretical curves is here exceedingly close, but those given by considering the higher moments of the curves demand placing the origin of the curve at respectively- 1.3 and 2.8 years before birth. When the origin is assumed to be at birth the fit is not quite so close. This, however, is what is a priori to be expected. Susceptibility to a fever cannot be expected to vary only according to only one law from birth to old age, even when the disease is essentially one affecting adults. To pass from enteric fever to t)'phus the statistics of the male patients suffering from this fever, and treated in Belvidere Fever Hospital, have been chosen for consideration. The diagram^ shows the kind of correspondence which the theoretical curve bears to the actual statistics. It will be seen that the theoretical curve has a course such that the curve of actual observations zig- zags backwards and forwards across it. One interesting variation noticed here, and also when the statistics of London are similarly examined, is that at the age of from forty to fifty-five years, the actual numbers are in excess of the theoretical ones. These are the years at which habitual drunkenness has fixed its mark on its de- votees, and it would seem to be indicated that such persons not only offer themselves more easy victims to this disease when attacked, but in addition are more susceptible to the infection. The same condition has likewise been noted clinically as predisposing to pneumonia. A similar diagram is given of the deaths among the same series of cases. Here on account of smaller numbers the actual curve is much more irregular than that noted among the cases, which number about eight times those of the deaths. The fit of the theoretical curve is thus not so close. When, however, the two are combined so as to form a theoretical mortality curve ^ Diagram II.