b. Circumstances influencing the Rate of Mortality.

1. Age exercises such a remarkable influence over the rate of mortality from typhus, that no just comparison between the rates of mortality at different times and places can be made, without taking into account the ages of the patients. In youth, it is far from being a fatal disease; but in middle and advanced life, when degenerations have already taken place in the tissues similar to those produced by the fever (see p. 16), it is most mortal. These facts may be ascertained by comparing the mean age of the fatal cases with that of those which recover; or still better, by determining the rate of mortality in each period of life. The former plan has been adopted with regard to the cases admitted into the London Fever Hospital during ten years (1848-57), and the latter with the cases admitted during twenty-three years (1848-70). The results are embodied in Tables XIII., XIV. and XV., and in Diagrams II. and VIII.

Thus, the mean age of the cases which recovered being 26, that of the fatal cases was nearly 42 years. Moreover, this difference of age not only applied to the cases admitted in the ten years collectively, but also held good for each individual year.

From Table XIV. it appears that the rate of mortality was somewhat greater during the first than during the second ten years of life. Thus, the mortality during the first five years of life was 6.69 per cent.; in the second lustrum, it fell to 3'59; between ten and fifteen it was only 2.28 per cent., and between fifteen and twenty, 4'46 per cent. After twenty, it went on progressively increasing (see Diagram VIII.), until of those

Above 30 years of age 35 39 per cent. died.

The mortality from typhus in the London Fever Hospital has been contrasted unfavourably with that in other institutions,

-95

90

-85

80

-75

70

65

60

-55

50

45

40

-35

30

-25

20

-15

10

5

Under 5 years

From 5 to 9 years

102014

Diagram

shows the Variations according to Age in the rate of Mortality of 18,138 cases

of Typhus Fever admitted into the London Fever Hospital (Compare with Diagr XIX)

but when a comparison is made between patients of the same age the discrepancy disappears. Compare it, for example, with that of the City of Glasgow Fever Hospital, in which, as already shown (p. 235), the total mortality has been remarkably low, and the smaller mortality is seen to have been in London.

When typhus has been fatal in the London Fever Hospital under fifteen years of age, death has almost always been due to

This Table includes the 10 patients dead before reaching the hospital. (See p. 234.)

• 10 patients dead before reaching the hospital have been deducted. Of the patients above 50, a larger proportion in London were very old. Of 878 male patients between 10 and 14 only 10 (or 114 per cent. died). Dr. Russell's Annual Reports.

Years

some severe complication. Thus, of 46 cases fatal in this period of life, of which I have notes, in 21 there was some severe pulmonary complication; in 9, convulsions; in 7, parotitis; in 5, cancrum oris; in 2, tuberculosis; in 1, meningitis; and in I, an infant only three weeks old, marasmus.

The increasing mortality of typhus as life advances has been a matter of universal observation. The following are a few illustrations.

Deaths

Mortality

per cent.

Total

818 116 14'18 36380

22°03 2,399 510 21'67 1.302 436 33°48

2. Sex. Most observations show that typhus is somewhat more fatal in males than in females. Table XIV. gives the results at the London Fever Hospital for twenty-three years. From this it is seen that, while the total mortality among males was 1967 per cent., that among females was only 18.2 per cent. Moreover, notwithstanding the supposed prejudicial influences of pregnancy and suckling, the mortality was, at every period of life above fifteen, less in females than among males, so that the prognosis in a woman sixty years of age would be as good as in a man ten years younger. But in this respect the patients between five and fifteen years of age presented a marked difference. At this period of life the mortality was twice as great among the females as in the males, while, deducting these cases, the rate of mortality in the remaining periods of life was 23.84 per cent. for males, and 21.7 for females.

k

Barker and Cheyne, Cowan,' and Huss showed that continued fevers were more fatal to men than to women, and their statements have been confirmed with regard to typhus by subsequent observations, as will be seen from the figures which follow:

PEACOCK, 1843.

BARKER and CHEYNE, 1821, i. 90.

Statist. Tables, 9th Ser. p. 14. 1 STEELE, 1848, p. 161. BARRALLIER, 1861, pp. 281, 375. The patients were prisoners, none under 18 years of age. 1 COWAN, 1838.

Huss, 1855, p. 58.

Cases

Deaths

Mortality

per cent.