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Scarlet fever—Seasonal variation in fatality.
In my last report I pointed out that the excess of the case mortality in 1894, compared with
that of 1893, was certainly influenced by two circumstances, viz., a considerable prevalence of disease
at the end of 1893 that affected the number of deaths in the early part of 1894, and a difference in
the two years of the age and sex distribution of the notified cases of the disease. Beyond this I gave
reasons for thinking that in an endeavour to determine the case mortality of a year consideration
should also be had for the seasonal distribution of the disease.
In the following tables is shown the monthly case mortality of scarlet fever for the four years
1892-5*, and for the year 1895, the case mortality of each month being calculated on the number of
cases of this disease notified in each month, and the number of deaths registered in each month
beginning one week later than that of the notifications, the object being to apply as nearly as possible
the deaths to the cases to which they belong. It will be seen on reference to diagram VIII., based
upon these tables, that the case mortality of the several months exhibits considerable variations, and that
there is a distinct indication of a seasonal fatality curve which has its maximum in the months of
January and December, and its minimum in the months of September and October, when the disease
attains its greatest prevalence.

* Previous to the year 1892 the age of the patient was unrecorded in a large proportion of the notified cases of infectious disease and
it has, therefore, been necessary to exclude the figures for 1890 and 1891 from these calculations.
† See footnote (*) page 33.