if possible, to obtain specimens of live rats trapped on board. He is required to
re-visit such vessels daily during the discharge of cargo, to ascertain whether dead
rats have been found in the holds. The existence of rodent Plague on board any
vessel in the Port should thus be detected at the earliest possible moment.
The Assistant Eat Officer's third duty is the examination of shore premises for
signs of rat infestation or rat Plague, paying particular attention to premises adjoining
the berths of vessels from Plague-infected ports. The whole of the Dock area is
systematically and regularly inspected, and specimens of the shore rat population in
all parts of the Port are regularly examined bacteriologically, so that, in the rare
event of Plague infection being communicated to the rats on shore, it should be
quickly detected and stamped out before it has spread extensively. Moreover, when
rat-infestation of premises is reported, the responsible persons are required to take
energetic measures of rat-destruction, for rat Plague will spread rapidly in a rat-infested
area, whereas where rats are few it may never spread at all. It is of the greatest
importance, not only from the public health, but also from the commercial point of
view, that the Port of London should be kept free from rat Plague.
Bacteriological Examination of Rats.— The bacteriological examination of rats for
plague is carried out in the laboratories of the Seamen's Hospital, Greenwich, where
there is a Staff of skilled bacteriologists under the direction of Professor Hewlett.
Assistant Rat Officers collect rats from ships and shore premises in their district each
day. They tie to one leg of each rat a small label, on which is a letter combination
indicating the Dock where the rat was obtained (thus R.A.D. indicates Royal
Albert Dock, S.C.D. Surrey Commercial Dock, &c.) and a number. In their daily
report sheets the Assistant Rat Officers enter each letter-number combination,
with notes opposite showing exactly where and how each rat was obtained.
They then place the rats in a linen bag, which they put in a tin box. At
the end of the day they deliver the tin boxes at the laboratory of the Seamen's
Hospital, Greenwich, and receive in exchange empty bags and boxes for the next
day's rats. Rats are delivered about 5 p.m., and examined next morning. If any
rats were found Plague-infected the letters and number on the label attached would
be telephoned to your Medical Officer, who, on reference to the Assistant Rat Officer's
reports, could at once ascertain exactly where such rats were obtained and institute
Plague preventive measures there. If rats are found dead under circumstances
suggesting that they have died of Plague, they are taken at once to the laboratory,
and an immediate examination and report is requested.
The rats from Tilbury Dock are sent by train from Gravesend to Greenwich,
where they are collected each morning by one of the Staff and taken to the laboratory
on his way to work.
It is not found possible to dip the rats on the Docks in a flea-killing solution,
but it has been arranged that the bags containing the rats should be dipped in kerosine
at the laboratory. The bags returned empty to the Assistant Rat Officers are
therefore saturated in kerosine, which is sufficient to destroy the fleas on the
subsequent batches of rats placed in the bags.
(2) Measures taken to prevent the passage of rats between ships and shore:—
The Port of London Authority have made Bye-laws requiring the Master of
every ship to cause all ropes and mooring tackle used for securing ships, either to
the shore or mooring buoys, to be fitted with guards, approved by the Authority, to
prevent rats passing from the ship to the shore, and to cause all empty cases, packages
and barrels to be examined before landing, to ensure that no rats are contained
therein. The removal of rats (alive or dead) from ships without previous consent in
writing of the Superintendent, is prohibited. Bye-laws also prescribe that, when the
discharge or loading of cargo or the landing or embarking of passengers is not actually
proceeding, one gangway, whitened for a length of 10 feet at the end next the vessel,
may be used as a communication between the ship and the shore, and that the Master
shall not have or allow any other communication with the shore, unless the same be
fitted with guards, approved by the Authority, to prevent the passage of rats.