Hints from the Health Department. Leaflet from the archive of the Society of Medical Officers of Health. Credit: Wellcome Collection, London
[Report of the Medical Officer of Health for London County Council]
In Calcutta the plague bacillus was reported present in cases of pestis minor amongst soldiers
of a regiment which arrived in Calcutta from Hong Kong whilst plague was raging in Hong Kong. It
is important that cases of so-called Bubon d'emblee, that is buboes occurring independently of a
venereal cause, should be carefully examined for plague bacilli when plague threatens or is prevalent.
The plague bacillus—Microscopic characters.
When from within a gland, or from the periglandular tissues, a small quantity of fluid is drawn
off by a hypodermic (or antitoxin) syringe and examined, bacilli will be found plentifully distributed
in the fluid. In the blood the bacilli may not be found until late in the disease. Search may also be
made for the bacillus in the faeces, in the urine, or in the sputum of pneumonic cases. In the pus of
recently opened buboes, or in the scrapings from the surface of an incised gland, a luxuriant crop will
usually be found. Old standing purulent discharges seldom show the bacillus. Post-mortem, almost
every organ of the body shows the presence of micro-organisms. They may be readily demonstrated when
a smear from any of these sources is spread on a slide, allowed to dry, and a staining fluid added.
The stain may be any one of the basic aniline dyes. The plague bacillus is a short, thick rod, with
rounded ends. In length it measures about 1.5u and in breadth 0.7u. The ends of the rod-like
bacillus stain much more deeply than the centre, and around the stained portion a clear area or
envelope is sometimes to be made out.
In stained preparations made from artificial culture, the bacillus may present the appearance
of a diplococcus, but occasionally four to six or more of the bacilli join end to end, resembling
Diagrammatic representation of the plague bacillus showing its relation in size to
the red corpuscles of the blood.
The plague bacillus, examined by 1/12-inch oil immersion lens.
Conditions as to the spread of plague.
Exposure to infection—It is most important to institute a careful inquiry into the possible
source of infection in every instance. This is especially important during the initial phase of an
outbreak, when by its detection valuable assistance may be rendered in devising immediate steps to
arrest the spread of the disease.