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8
diphtheria.

House, Family Distribution.—For the consideration of this question the cases have been
divided into two groups viz: "Institutional" and "Family" the former comprising cases
occurring among the residents (and/or in-patients) of all classes of institutions, the latter, cases
occurring in the patients' homes. The '259 cases reported in 1919 included 20 "institutional"
cases (7.7 per cent.) and the 464 reported in 1920, 39 (8.4 per cent). The percentage for the two
years together was 81 per cent, as compared with a ratio of 8.8 per cent for the five years
1914-18.
After excluding "institutional" cases, there remain 239 "family" reported in 1919, occurring
in 207 houses and 211 families—giving averages of 1.1 case per house and family. In 1920
425 "family" cases occurred 370 houses and 371 families—averaging the same (1.1 per house
and family). Combining the two years, the averages work out at 1T5 cases per house and
1.14 per family, slightly in excess of the corresponding averages (T08 per house and 1.07 per
family) for 1914-18. The foregoing figures are based on the cases reported without correction
for errors of diagnosis.
The secondary cases (in houses) numbered 31 in 1819 and 55 in 1920, the ratios being
13.6 per cent. of all cases (corrected for errors) in 1919 and 13.9 per cent. in 1920. For the two
years secondary cases formed 13.8 per cent. of all verified cases, as compared with 9.4 per cent.
during 1914-18.
The frequency distributions of multiple attacks per house—expressed as percentages of all
houses invaded during 1919-20 and 1914-18 are compared below :—
Cases per house 1 2 3 4 5 6
1914-18 92.6 5.6 1.3 0.4 — —
1919-20 8.92 7.8 2.1 0.7 — 0.2
Errors of Diagnosis. — In 1919 the reported cases included 12 "errors" (4.6 per cent.) and
in 1920, 31 (6.7 per cent). For the two years the proportion was 5.9 per cent., as compared
with an average of 8.1 per cent. during 1914-18.
Bacteriological Diphtheria.—The certification of diphtheria was, during 1919, based on
bacteriological test in 135 instances (52.1 per cent.) and in 1920, in 217 (46.7 per cent).
Negative results of such tests do not, however, rule out a diagnosis of diphtheria, and in 1919
the disease was certified in 15 instances in which the test was negative and in 8 during 1920.
These tests are of great value but the general use of "swabbing'' as had one result which was
not anticipated, namely, an increase in the number of cases of dip theria reported, which gives
a misleading impression of increased prevalence of the disease. proportion of cases which
are certified as "Diphtheria" as the result of a positive test present no clinical symptoms of the
disease. The individuals yielding such positive results are reahy" "carriers" of the disease,
either temporary or chronic. The part which carriers play in spreading clinical diphtheria is
not definitely known, but such persons must be regarded as dangerous to the community.
Much work has still to be done to clear up this important question, and although the subject
cannot be discussed here the following figures are given as illustrating how "bacteriological
diphtheria"—carrier cases—swell the records of notified diphtheria.
In 1918 6,762 cases were, admitted to the Asylums Board's Hospitals as "diphtheria,"
which total included 381 cases (5.6 per cent.) of "bacteriological diphtheria." The proportions
admitted from the Boroughs varied from a maximum of 17.7 per cent. (Holborn) to a
minimum of 1.9 (Hammersmith). From Paddington 31 such cases (14.4 per cent.) were
admitted.