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34
Annual Report of the London County Council, 1913.
bacillus if it is to be "effective," or alternatively, that no final deductions can be drawn from the
presence of single bacilli, and that insistence must be laid upon the question of dosage.
These most laborious and thorough inquiries of Dr. Houston will necessarily tend to confirm many
students of this difficult question in the view that presence of the typhoid bacillus is not the same thing
as potential infectivity ; the close association of typhoid bacilli with typhoid fever in man lends strong
support to Koch's doctrine that the human body is par excellence the manufactory of typhoid bacilli,
but the evidence laboriously collected by Koch's followers with a view to demonstrating how the typhoid
bacillus obtains access to the body and sets up typhoid fever rather tends to supply the rival theory
that it is typhoid fever which leads to development of the typhoid bacillus in the human subject.
Dr. Houston, approaching the problem from quite a different standpoint, also obtains results
which most readily find explanation on the hypothesis that the bacillus should be looked upon as effect
rather than cause.
Dr. Houston, five years ago, in his Third Research Report (p. 18), in giving a carefully considered
opinion as to the value of storage, referred to certain "qualifying considerations, '' and among these was
the fact that "epidemiologists are displaying a not new but aggravated tendency to question the integrity
of the reputed causal agents of certain waterborne diseases. Some, indeed, go so far as to consider
that the typhoid bacillus and cholera vibrio may, in a causal sense, come to share the inglorious fate,
in this respect, of the hog cholera bacillus.'' Dr. Houston's own work in the last five years, from one
point of view, rather tends further to aggravate the tendency mentioned. Demonstration of the presence
in two instances, and the consequent presumption of the presence in considerable numbers of bacilli indisinguishable
from typhoid bacilli in drinking water, which epidemiologically considered has during recent
years not fallen under suspicion, once more raises question as to the significance to be attached to the
presence of such bacilli. Twenty years ago importance was attached to the argument that the bacilli as
known in the laboratory could not survive a run down a river like the Tees. Dr. Barry, in giving evidence
before the Water Commission (1892.93), said: "If it is found that what is called the specific bacillus
of typhoid fever will not live under particular circumstances, as has seemed to be shown by laboratory
experiments then I think that possibly the true bacterium has not been found." Now, thanks to
improvements in bacteriological technique, the pendulum has swung the other way, and Dr. Houston
finds no dearth but an embarras de richesses. Thus, as has already been pointed out elsewhere (Trans.
Roy. Soc. of Med. 1906-07): "During the last fifteen years a new difficulty (has) arisen inasmuch as it
has been ascertained that large communities can with impunity be supplied with polluted river water
for periods of some years, without manifest injury, provided certain precautions are adopted, and these
it would seem are not of a kind which necessarily precludes the bacillus from obtaining access to household
supplies." The experience of the last seven years goes to confirm the view expressed in 1907.
The difficulty now is not to explain how the bacillus can survive, but why bacilli which survive do not
cause mischief. The suspicion necessarily arises as to whether it may not be necessary to look elsewhere
than to these bacilli for the cause of typhoid fever. If, for the sake of argument, it could be assumed that
the causa causans of typhoid fever is stopped by a sand filter, the close correlation between the carrying
into effect of improvements in the treatment of raw river water and diminution of water-borne typhoid
might in part be explained, and it would then be no longer difficult to understand Dr. Houston's results.
Typhoid
fever
in London
boroughs.