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87
Caseous Lymphadenitis.—This disease, sometimes called
"pseudo-tuberculosis" occurs mainly in sheep although it is
occasionally found in cattle, rabbits and chickens. It is met
usually in imported sheep carcases and is often the cause of meat
being rejected as unfit for human consumption. It follows, therefore
that much time and attention is given by the Food Inspectors
to this disease during their inspections at the wharves and cold
storage plants in the Borough.
Results of examinations for caseous lymphadenitis are given
below.
Landed Examined Rejected Weight
Australian Sheep, Ewes & 1 pr. short
Wethers 29,642 342 forequarters 18 lbs.
New Zealand sheep65,453 671 1 leg 5½lbs.
Imported, Egg Albumen.—In 1956 there were greatly increased
landings in this country of Chinese Dried Egg Albumen and from
June until December, Greenwich received over 100 tons. This
commodity in the previous year had contained salmonella organisms
of various strains and some batches contained paratyphoid B.
Extensive sampling in Greenwich confirmed these general findings.
Because of the urgency of the problem a National Albumen
Advisory Committee was set up consisting of representatives of the
Importers, the Ministry of Health, the Public Health Laboratory
Service and Food Research Organisations to consider methods of
processing to render the product bacteriologically safe. Heat
treatment eventually was considered to be the only effective solution
and after many experiments it was decided that the albumen
should be heated to a temperature of between 127° and 128°F. in
specially constructed heat treatment chambers. Accordingly,
several Heat Treatment Centres were set up throughout the country
and a storeroom at Palmer's Cold Stores, Deptford, was adapted
for this purpose. This room, which is capable of holding 40 tons at
a time was heavily insulated and appropriate electrical heating
equipment was installed to maintain the required temperature within
very fine limits.
The egg albumen was subjected in the first instance to 100 per
cent. bacteriological examination by the Health Department, before
being loaded into the heat treatment chamber. The temperature
was then raised to between 127° and 128°F. and held at that level for
at least six days before being allowed to cool gradually. The complete
process takes about ten days.
Batches found to be positive before heating were again subjected
to bacteriological examination and in every case positive tins were
found to be negative after treatment.