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86
From this Table it will be seen that the percentage of
nuisance in houses affected, is smaller and that the percentage
of removal to hospital much larger in 1899, which points
to the increased care and activity on the part of the Inspectors.
It will also be seen that out of 433 cases, only
227 were attending School at the time of which the disease
was notified. This shows to some extent that school infection
cannot be the main factor in the spread of the disease,
although in many instances it undoubtedly assists. The
question remains, what is the cause of the prevalence of
diphtheria in this part of the District. In my opinion the
causes are two. (1) The 1 earness of this part of the District
to a slowly running river, from which there must always be
a considerable amount of dampness in such a low lying
neighbourhood. (2) The condition of the combined drainage.
This last condition is being remedied, and will soon be
entirely so; and I have every hope that when this has been
done, with more const ant attention to the cleansing, &c., of
these houses in this neighbourhood, we may be able to keep
this part of the District as comparatively free from diphtheria
as is the rest of this District. The question of the river is
one with which it is more difficult to deal. It was suggested
that possibly some contamination of the water might occur
from the Chaffinch Brook, which runs into the Ravensbourne,
and into which brook the effluent from the Croydon Sewage
Farm runs. A sample of the water of the Chaffinch Brook,
just below the entrance of the effluent from the sewage farm,
was taken and sent for analysis to Dr. Rideal, the Board's
analyst. The result of the analysis was as follows :—
Analysis in parts per 100,000.
Total solids 92.4
Chlorine 8.0
Free Ammonia 0.595