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45
Rodent Control
Rats and their control have for many years been a serious problem
in the Borough and infestations are of two types. Rattus norvegicus
or the common rat is commonest in the residential parts of the Borough
and invades properties from a large reservoir in the sewers often
finding an egress through broken drains. During the times of air
bombardment an intensive effort was made to fill up disused drains and
to seal off their openings in the sewers and these have been continued
since together with the undertaking of much repair work to old worn
out drains, but many damaged plus some disused drains remain: also
some rats escape in other ways such as where interceptor caps have
been removed. The other type of rat is rattus rattus which breeds in
the large warehouses in the South of the Borough.
Soon after the war a block treatment of the whole borough was
carried out and temporarily reduced the rat population considerably.
The rats in the sewers and underground waterways form the most important
reservoir. Although their numbers have been reduced, they
quickly increase again if control efforts are relaxed. Throughout,
attention has been given to clearing the sewers as far as possible and
six-monthly treatments have been carried out in association with
neighbouring boroughs.
In 1952 one or two cases of Weil's disease with one death
occurred in sewermen and special six-monthly treatment of the sewers
in the area where it was thought this disease was contracted were
carried out for two years. In July 1955 modifications were introduced
into the methods adopted but it is too early to comment on the
results.
Over recent years there has probably been some reduction in the
number of surface infestations of the common rat but this cannot be
claimed for rattus rattus.
Inspection and general surveying is carried out continuously and
all complaints are investigated and treated according to the circumstances.
Pull co-operation with the public has been achieved and no
formal action under the relevant legislation has been necessary for
some years. There has been a considerable increase in 1955 in the
amount of rodent control carried out by the department on behalf of
business firms.
The normal method of pre-baiting has been usually adopted followed
by the use of one of the recognized poisons. In the case of
infestations by rattus rattus warfarin without pre-baiting has been
employed on occasions. Wherever possible rat proofing by the owner
has been pressed.