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108
have been omitted and the groups of eases numbered
consecutively. Any group can be identified by
reference to the preliminary tables which have been
preserved.
Scarlet Fever. —During 1897, 490 cases of this
disease were notified from 366 houses, distributed as
follows:—
From 281 houses, 1 case
,, 56 ,, 2 cases
„ 21 „ 3 „
„ 6 „ 4 „ and
„ 2 ,, 5 ,,
In 56 of the 85 groups of cases,* the spread of
infection was apparently due to the operation of
causes (a) and (or) (b). The groups are:—Nos.
2-4, 8-12, 15, 17-19, 23, 25-28, 33, 34, 36-44, 47-60,
62, 66, 68, 69, 71, 74, 76-79, and 81-84.
In 18, cause (c) appears to have been operative,
viz.:- Nos. 1, 6, 11†, 16, 21, 24, 30-32, 35, 61, 64,
65, 67, 70, 73†, 80, and 85.
In 13 groups, none of the three causes already
specified appeared to have operated, viz.:—Nos. 5,
7, 13, 14, 20, 22, 29, 45, 46, 63, 72, 73†, and 75.
In these cases it was impossible to eliminate the
possibility of independent fresh sources of infection.
For the present purpose they may be assumed as
due to failure of the process of disinfection.
* By a "group of cases" is meant the cases occurring in any one house.
† Groups 11 and 73 are mentioned twice owing to differences in the
circumstances attending certain of the secondary cases in each group.