2 . Plague in Human Beings.— T h e s e
s p e c i m e n s
w e r e s e n t m a i n l y f r o m s e g r eg
a ti
o n
camps, hospitals, and usually in connection with passport holders. About 25
per cent. of these showed. a positive result, but it is chiefly the specimens showing a
negative result that need. be discussed here. A very large proportion (25 per cent.)
were totally unsuitable for the purpose for which they were sent. Apart from the
disappointment of an inconclusive result, this means a considerable waste of time for
all those concerned. No less. than 118 .of these unsatisfactory .specimens were peri
pheral blood. It seems strange that after so many years experience of plague ,it
should not be better known that plague bacilli cannot be detected Microscopically in
the peripheral blood of doubtful cases. It is true that plague may be considered a
septicæmic disease and that under certain circumstances, especially shortly before
death, plague bacilli may occur in the blood in considerable numbers. In such cases
however miseroscopical examination of the blood will yield no new information.
It is also true that by suitable cultural methods plague bacilli may frequently be
isolated from the blood in an early stage of the disease, but in order to do so, as much
as one or two cubic centimeters of blood must be used. That is in such cases one
plague bacillus may be present in one or two cubic centimeters of blood. Now only
a very few cubic millimeters of blood can be efficiently used in preparing a filmy
1/400th cubic centimeter say, and it would be difficult indeed to examine such a.
film so systematically as to say with confidence that a single bacillus had not escaped
detection.
Altogether it may safely be said that the chances against detecting plague bacilli
in the peripheral blood of doubtful cases are as many thousand to one.
In this connection it may be pointed out that sputum is also a very unsatisfactory
material to send for examination in suspected plague. In a typical case of primary
plague pneumonia plague bacilli can be detected in enormous numbers and are present
practically in pure culture. In such cases however microscopical aid to the diagnosis
is hardly necessary. In the pneumonia so frequently a secondary complication of
other forms of plague, the sputum is swarming with innumerable varieties of other
organisms derived from the upper air passages and it is impossible to say definitely
whether plague-like forms are genuine plague or not. Shortly, where the clinical
picture is one of primary plague pneumonia, microscopical confirmation is not required ;
where the clinical picture is doubtful, microscopical diagnosis is also so doubtful as to
be of little value.
For the diagnosis of plague, proper preparations to send are :--(a) In living cases
films of material obtained from the bubo before it has commenced to suppurate, (b)
from corpses films prepared from the liver or spleen.
In preparing films from a bubo, care should be taken that the material used is
actually obtained from the bubo and not from the surrounding tissues.
3. Testing for the agglutination reaction has been limited mainly to typhoid
bacilli, undoubtedly its most useful form in India, but infections from allied forms are
not without importance. An investigation of the latter on a prolonged scale would be
of great interest. Unfortunately every addition to our technique, so far from leading
to finality, seems only to reveal new species requiring differentiation.
4. A notable feature revealed by examination of the specimens submitted for the
diagnosis of malaria is the large number of negative results 85—per cent. This is
probably largely due to the practice of administering quinine before preparing films of
the blood. This practice, in these days when it is well known what valuable information
can be derived from a microscopical examination of the blood, can only be described
as little short of reprehensible. Numbers of the spedimens yielding negative results
showed the definite mononuclear increase so often met with in cases of malaria, but
most careful searching failed to discover any parasites and so the diagnosis could not
be clinched.
In some hospitals and . cliniques it is the custom to withhold quinine until mala
rial parasites have been demonstrated. This is an entirely logical procedure, but in
circumstances, where, for various reasons, microscopic examination may not be imme-
diately available must still be held to be a counsel of perfection. The taking of a film
however is such a simple proceeding that it can be arranged. for by any one desirous of