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His second duty is the examination of ships in his area which are due for inspection under
Article 19 of the Public Health (Ships) Regulations, 1952, and the Prevention of Damage to
Pests (Application to Shipping) Order, 1951-6, relating to the granting of Deratting and Deratting
Exemption Certificates and Rodent Control Certificates respectively.
The Rodent Operative'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.
Some twenty years ago 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.
(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 polythene 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.
The rat population of the Port is now so small and is under such strict control that it can be
said to be almost certain that the arrival of a plague infected rat, even should it manage to get
ashore, would be highly unlikely to have any serious significance. In other words, an epizootic
could not be introduced into the Port for the simple reason that there are insufficient rats to
enable the spread of infection. Nevertheless, eighty-one rats were sent to the Laboratory and
were examined for plague with negative results.
(3) Arrangements in the district for deratting ships, the methods used, and if done by a commercial
contractor, the name of the contractor.
(a) The burning of sulphur at the rate of 3-lbs. per 1,000 cubic feet of space for a period of
not less than six hours.
(b) The generation of hydrocyanic acid gas by various methods. For the destruction of rats
a concentration of HCN at the rate of 2-ozs. per 1,000 cubic feet of space is required
with a minimum of two hours contact.
(c) "1080" and "Warfarin". The employment of "1080" has been used regularly throughout
the docks for some time with highly satisfactory results both on shore and in ships. A
substantial number of ships have been deratted by this method in preference to the use
of cyanide, resulting in a considerable saving of time and cost to the shipowner.
Although satisfactory results have been obtained from the use of "Warfarin" a
suitable bait has yet to be found, particularly in granaries, with which to mix the poison,
so that rats will take it continuously in preference to grain and other forms of cereal on
which they are normally feeding.
(d) Trapping. Trapping is seldom employed save for the destruction of isolated rats which
have escaped a major poisoning operation or which have not yet established themselves.
(e) Methyl Bromide. This is a very effective and lethal fumigant which has been used in
this Port as an insecticide, particularly in the dry fruit industry. It has considerable
penetrating powers and is not difficult to disperse after an operation. It is also possible
to use this gas as a rodenticide and where there is an infestation of rodents and
insects the combined problem can be solved with one operation.
The following are the names of the firms approved for carrying out the deratting of ships:—
Messrs. Associated Fumigators Ltd. Rentokil Laboratories Ltd.
Messrs. London Fumigation Co. Ltd. Contra-Pest Service Ltd.
The P. & 0. Orient Line
GENERAL OBSERVATIONS ON RODENT CONTROL
In any form of organised rodent control there will always be a measure of urgency; there is
need for intelligency, technical skill and persistent effort if the wiles and tenacity of rodents are
to be overcome, a need which is all the greater in a major seaport such as this, with its complex
pattern of international commerce involving numerous ships, harbour craft, shore premises and
transport vehicles ; control must also be exercised with the minimum of obstruction to the trade
of the port.
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