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Any such rats are immediately sent to the Central Public Health Laboratory at Colindale for
examination for bacillus pestis, each rat being accompanied by a label on which is given precise
information as to where the rat was found in order to arrive at a focus of infection should the examination
prove positive.
In the event of a positive result the discharge of the cargo would be promptly stopped and,
if necessary, arrangements made for the vessel to be fumigated throughout with hydrogen cyanide,
with the cargo in situ, the vessel being removed to an approved mooring.
Following the initial fumigation and collection of dead rats, further samples of which would be
submitted for examination, the discharge of the cargo would be permitted under observation. The
destination of the cargo would be ascertained and a note of the circumstances would be forwarded to
the Medical Officer of Health of the district to which the cargo was proceeding.
Should any of the cargo be discharged overside into lighters, such lighters would be fumigated
immediately they were empty.
On completion of the discharge of cargo from the vessel a second fumigation would be carried out
again using hydrogen cyanide to destroy the residual rat population, if any.
SECTION XII—Measures against rodents in ships from foreign ports.
(1) Procedure for inspection of ships for rats.
The Port Health Authority employs fifteen Rodent Operators working in conjunction with and
under the supervision of the Sanitary Inspectors.
The Rodent Operator's first duty is the examination of such ships in his area as are due for
inspection under Article 19 of the Public Health (Ships) Regulations, 1952, relating to the granting of
Deratting and Deratting Exemption Certificates.
His second duty is to visit all ships arriving in his district, to search for evidence of rats, paying
particular attention to vessels which have arrived from plague infected ports and to visit such vessels
during the discharge of cargo.
The Rodent Operator's third duty is the examination of shore premises for signs of rat infestation
paying particular attention to premises adjoining the berths of vessels from plague infected ports.
In 1941 the Port Health Authority instituted a Rodent Control Scheme in all docks and premises
of the Port of London Authority, on behalf of that Authority and in the premises of the tenants of the
Authority on behalf of the occupiers.
This scheme in its early days relied principally on trapping but with experience and the application
of a more up-to-date knowledge of the habits of rats, new and scientific methods of poisoning
gradually took the place of trapping, the latter now only being occasionally used to clear up residual
rats, if any, which have escaped a major poison operation.
The Port of London Authority have made byelaws requiring the Master of every ship to cause all
ropes and mooring tackle to be fitted with guards to prevent rats passing from ship to shore. The
byelaws also prescribe that when the discharge or loading of cargo is not actually proceeding, one
gangway, whitened for a length of 10 feet at the end next the vessel, may be used as communication
between the ship and the shore.
(2) Arrangements for the bacteriological examination of rodents, with special reference to rodent
plague, including the number of rodents sent for examination during the year.
As described in Section XI above all rats for examination for plague, either by post mortem and
subsequently, if necessary, by bacteriological examination, are promptly sent to the Central Public
Health Laboratory at Colindale.
The bodies are placed in canvas bags which in turn are placed inside metal boxes, sealed and
labelled so that there is no risk of the escape of any rat fleas during their transit to the Laboratory.
The boxes are, of course, delivered by hand.
Examination of rats for evidence of plague being a public health measure, is now carried out at
the Government Laboratory at Colindale free of charge, representing a considerable saving in cost to
the Port Health Authority.
The routine Laboratory examination of rats found dead from an unknown cause has been a regular
practice in this Port for many years and it would appear to be a necessary and desirable precaution.
Even the practice of sending rats killed by trapping or poisoning or a proportion of the number so
killed would appear to be desirable.
RODENT CONTROL.
Field Experiments with a New Preparation—" 1081."
Although highly satisfactory results are obtained throughout the Port by using Sodiumfluoroacetate
("1080"), "Warfarin" and Zinc Phosphide in order to poison rodents in appropriate
circumstances, some experiments have been carried out during the year with another substance—
Fluoroacetamide, which is a derivative of Sodium-fluoroacetate.
It can be dispensed and used with the same technique as "1080", i.e., to deploy the baiting
points as poisoned drink and/or food.
" 1081 "—Physical Characteristics.
Unlike "1080" powder, which is fine and buoyant in air currents, Fluoroacetamide is of a
coarser crystalline nature and much less liable to become air-borne as a hazard to the dispenser.
It is almost readily soluble in cold water, forming a colourless and odourless solution.
Because of its close relation to "1080", Fluoroacetamide has been designated "1081" during
the several field trials to which it has been subjected.
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