London's Pulse: Medical Officer of Health reports 1848-1972

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City of London 1961

[Report of the Medical Officer of Health for Port of London]

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(c) Prawns
In 1959 examination of samples of Japanese prawns
showed the presence of coagulase-positive staphylococci
of food poisoning types. No statutory bacteriological
standard was available to aid assessment as to fitness.
Surface plate counts as high as 75 million were reported,
and of 110 samples, 16 exceeded 2,000,000 either with or
without staphylococci of food poisoning types.
A number of conferences were held at which my
riparian colleagues and I discussed the position with
bacteriologists of the Central Public Health Laboratory
and medical officers of the Ministry of Health in an
endeavour to formulate some standard which could
reasonably be applied to prawns, and it was agreed that
application of a fairly simple standard appeared to give a
reasonable assessment of fitness. A two-day surface plate
count at 37°C of 250,000 per gm. or less is perfectly
satisfactory. Anything in excess of 2,000,000 is regarded
as unfit, and within this range the presence of coagulasepositive
staphylococci and B. coli are taken into account.
In any case of doubt and in all cases when rejection is
contemplated, further samples are taken, the examination
results of which have always enabled an assessment to be
Earlier shipments bore no labelling of any description,
and it was considered that cautionary labelling should
properly appear on the cartons of such items of food so
readily susceptible to spoilage and possible proliferation
of contaminating bacteria if improperly stored. The
importers co-operated by requesting their shippers to
label all packs:
(i) Keep contents at "deep freeze" temperature until
ready for use;
(i) Allow to defreeze at normal temperature;
(iii) Do not re-freeze.
This has now been adopted generally by packers.
To Japan have been added Brazil, Spain, China, Egypt
and India and as each new importer enters the trade so
one must be prepared for the teething troubles of high
plate counts, presence of staphylococci and absence of
cautionary labelling.
Reviewing the results of sampling for 1960, an improvement
is apparent. Of 115 samples only two had
surface plate counts exceeding 2,000,000, the highest being
3,500,000 and faecal contamination was greatly reduced.
The main problem was to evolve an agreed provisional
standard against which bacteriological reports could be
measured. In dealing with an article of food such as
prawns, the medical officer of health is not entitled to
take into consideration the potential danger of improper
storage, or the danger that might arise in the smaller
restaurant by keeping an opened carton for a considerable
time, with consequent liability of bacterial multiplication
to dangerous proportions.
These shipments are of considerable value, but in no
case has it been necessary formally to seize any shipment
for a Justice's decision, the importer always having
voluntarily surrendered the goods upon explanation of
the reasons for rejection.
(d) Livers
A few years ago a significantly increasing volume of
imported livers, mostly marked as intended for animal
feeding purposes, drew attention to the fact that no means
of control existed in regard to such meat, whatever may
have been the suspicions that all was not in fact sold for
consumption by animals.
Shipments invariably passed through many hands
before disposal, but a number of consignments were
traced to the point of final disposal, some finding their
way into chain retail butchers' shops.
It must be remembered that port health authorities
had powers only in respect of meat intended for sale for
human consumption.
Inspection had shown that a high percentage of the
livers were affected with the Echinococcus cyst, a stage
in the life cycle of the dog tape worm; the cause, in at
least one recorded case, of a human death. If, as was
suspected, some of this liver was being sold for human
consumption, the medical officer of health surely had a
moral duty if not a statutory one in his regard for the
public health.
This was the position then. In the course of perfectly
legitimate trade these livers were imported for animal
feeding, the importer probably being quite unaware of the
condition of the meat. By the time it had been sold and
resold the original intention may have become less binding,
and as the affection was not readily apparent without
incision, and once divorced from the sack and its marking
all identity was lost, to all intents and purposes there was a
perfectly good liver fit for human consumption. By this
time, however, the shipment had passed out of the hands
of the port health authority and no authority had any
official interest in its whereabouts or disposal. At the
worst it was sold for human consumption; at the best
people were in effect feeding their dogs with embryo tapeworms.
The problem of gaining effective control was engineered
by the application of section 111 of the Food and Drugs
Act, 1955, which allows the presumption that an article
of food, stored in a place in which similar food intended
for human consumption is usually stored, is intended for
human consumption unless the contrary is proved.
A consignment of affected livers was removed from the
Port of London into a cold store in the City of London,
in which fit livers for human consumption were stored.
The consignment was promptly presumed to be intended
for human consumption, inspected and found to be unfit,
seized and taken before a Justice who condemned them as
unfit for human consumption and ordered that disposal
be made to the satisfaction of the medical officer of health.
The medical officer of health agreed upon release for
animal feeding purposes only if the eventual user gave a
guarantee as to use, and upon receipt of this document
final disposal was passed into the jurisdiction of the local
medical officer of health for his control.
Once some control over this meat was established a
system of voluntary advance notification of shipments of
meat not intended for human consumption was adopted.
Notification included details of eventual user and address.
This imposed no interfence with legitimate trade in this
class of meat, and in fact facilitated rapid clearance in the
docks. It is noticeable that no applications are received
for disposal to retail butchers' shops.
There is little doubt that this particular problem did
much to bring into being the Meat (Staining and Sterilization)
Regulations, I960, whereby all unfit imported and
butcher's meat must be sterilized before sale.
An incidental point arising from this is the insistence of
many pet owners that raw meat only be fed to their pets,
but this may not always be in their best interests.
(e) Salmonella contamination of meat
The incidence of salmonella contamination of boneless
meat imports generally has led to routine check sampling
of such shipments for bacteriological examination so that
contaminated cargoes may be diverted into the canning
factory or other manufacturing channels where the heat
process involved would destroy the organisms.
Early in 1960 a shipment of boneless meat from a
country newly entering the meat trade was routine
sampled. Of 10 samples taken five were reported as
salmonella contaminated, in one of which heat-resistant
Clostridium welchii type 10 was also found. There were no
grounds, at the time of sampling, to justify detention of
the shipment and by the time the bacteriological reports
were received it had been distributed, but it was decided
that future shipments would automatically be detained to
await bacteriological reports.
Shipment no. 2 of this meat was discharged at a wharf
in the City of London. The shipment was placed under
detention and removed to various cold stores in the City
and in Finsbury. The report on 22 samples from this
shipment showed no salmonella and the shipment was
released accordingly.
Shipment no. 3 was discharged and distributed into
cold stores in the City of London, Bermondsey and
Finsbury. Ten samples from the City Cold Stores were
examined, no salmonella being found, but a report was
received from another district that Salmonella typhimurium
had been isolated from part of the shipment.
Shipment no. 4 was reported salmonella free. Shipment
no. 5 consisting of bone-in-beef hindquarters and boneless
meat was detained. No positive reports were received on
the bone-in-beef samples and this was accordingly
released, but four of 17 samples of boneless meat were
reported as "salmonella found" three of which were
Salm. typhimurium.
The boneless meat consisted of specified cuts, strip
loins, hindquarters, flanks, topsides, rumps, silversides,
crops, briskets, forequarter flanks, thick flanks, shins,
fillets and full crops, and further sampling of each cut was
carried out. Salmonella organisms were isolated from
samples of silversides, shins, topsides, and forequarter
flanks, and all but these cuts were released.
Further sampling of the detained cuts resulted in the

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