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The Rodent Operative's first duty is to visit all ships arriving in his district to search for
evidence of rodents, paying particular attention to vessels which have arrived from plague
infected ports and to visit such vessels during the discharge of cargo and to ascertain that
reasonable measures are adopted to prevent any rodents escaping ashore.
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, 1952-61, and the Prevention of Damage by
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 ye ars 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, one hundred and twelve 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. This method is seldom used in the Port of London.
(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. London Fumigation Co. Ltd. Rentokil Laboratories Ltd.
The P. & O. Orient Line Contra-Pest Service Ltd.
RODENT CONTROL ON LIGHTERS
Effective control in this particular field assumes special significance when considered as an
indicator of conditions in the whole port. These craft ply between ships, wharves and docks, and
therefore, could act as transports for rodents to and from the many warehouses and ships. The
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