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40
Annual Report of the London County Council, 1912.
the question has really become—What degree of importance should be attached to the demonstration
of the presence of typhoid bacilli in the blood or excreta of a particular individual? And here the question
has been complicated, in one sense, by the discovery of "enrichment methods" of cultivation; for the
bacillus can now be demonstrated under conditions in which a few years ago it would have been hopeless
to attempt to find it. It is true that in dealing with the hitherto generally recognised vehicles of
infection, water, milk, etc., few positive results have been obtained; von Drigalski was only successful in
finding the bacillus in one sample of water, and in this instance no cases of illness resulted from drinking
the supply in question. But, on the other hand, the bacillus has been found under the most unexpected
circumstances, e.g., in collections of pus or in gallstones years after an attack, or indeed in the absence
of any history of an attack of typhoid; again, it has been found in the excreta, in numerous instances,
where no history of previous attack of typhoid is forthcoming. One method after another of isolating
bacilli from the blood and excreta has been recommended, better and better results being claimed for
each new departure made, until at length one of the German reporters writes (p. 525), "It is not so much
the method employed that matters, it is rather the practical experience gained of it, and the patience
of the observer that count."
All this has undoubtedly tended to excite criticism, and in the minds of many to cast doubt upon
the position taken up by Koch; but two considerations, in particular, indicate that some modification
of his view is necessary. In the first place there are the difficulties presented by the case, in many ways
so closely parallel to that of the typhoid bacillus and typhoid fever, of the paratyphoid bacillus and
paratyphoid fever. The German writers fully admit the difficulties presented in the case of the latter.
Reports from all the stations, it is said, agree (p. 95), that it is quite common to meet with paratyphoid
bacilli in healthy persons, who have not been exposed to the infection of paratyphoid fever; and, again,
so variable are the conditions associated with the presence of paratyphoid bacilli, that we are told
(p. 543) paratyphoid fever cannot be regarded as a clinical term, but must be locked upon as an
ætiological one. It is difficult to define the ætiological role of a bacillus which anyone may excrete and
which is not necessarily (even when it does occur in a sick person) associated with any particular kind
of disease. In the second place, bacteriological theory has undergone a remarkable change during the
last five years. The demonstration of the secondary role played by a number of supposed causal
organisms, and the proofs gradually accumulating of the liability of bacteria to undergo so-called
"mutation," have done much to render unsettled ideas as to the criteria which should be held to delimit
a bacterial species.
To all this development of knowledge large and important contributions have been made by
German bacteriologists, and the campaign in South West Germany, if it has not done much to throw any
direct light on the spread of typhoid fever, has at least contributed materially to growth of knowledge
concerning the typhoid and paratyphoid bacilli.
Enteric fever
in London
boroughs.