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notification of cases of food poisoning. The memorandum emphasises,
however, that investigation of outbreaks has revealed some important
factors in their causation and give the following list.
(i) The foodstuff or one of its ingredients may be primarily infected
and the infection may survive the cooking or other preparation of
the food.
(ii) A primarily infected article may contaminate equipment and lead to
secondary infection of other food products.
(iii) The amount of noxious material which survives cooking may be so
small that no harm would result from immediate consumption. With
delay in consumption, however, inappropriate storage, including
misuse of refrigeration, and bad handling can lead to such growth
of organisms, sometimes with the formation of enterotoxin, as will
cause frank disease.
(iv) An infection introduced by food handlers can survive and multiply
in such products as cream, imitation cream, custard and table sweets,
cold meat, meat products, soups and gravies. These foods can easily
become dangerous under certain conditions of domestic storage,
though they would remain sound and comparatively free of risk
if stored under ideal conditions in well-equipped premises.
Sixteen cases of food poisoning were notified by medical practitioners
and six others found during the investigation of sources of infection. One
outbreak occurred which involved six people and the story of this outbreak
is typical of many cases of food poisoning as shown in (iii) above.
Some beef was cooked on a Friday and then placed in a meat safe in a cupboard
below the stairs until Sunday when the family ate some of it cold.
No ill effect resulted from this meal. The next day the family ate more of
the cold beef for the evening meal and about 2-3 a.m. on Tuesday all six
had violent abdominal pains and diarrhoea. Heat resistant Clostridium
welchii, type 3, were isolated from the meat and also from faecal specimens
submitted by four of the patients, another proved negative, and one
refused to co-operate in the investigation.
The condition required before food poisoning organisms can cause
illness are food, moisture, warmth and time to increase in numbers.
The beef was infected by heat resistant cl. welchii which survived the
cooking process but in insufficient numbers to cause illness. No illness
was caused at lunch time of Sunday but by Monday evening the numbers
of organisms were sufficient to make the family ill.
No other outbreaks occurred but there were sixteen single cases,
eight due to s. typhi-murium, one to s. Derby and another to CI. Welchii.
Compensation amounting to £9 18s. 4d. was paid to a woman excluded
from work as a suspected case of food poisoning. The case proved to be
positive to s. typhi-murium but quickly responded to treatment.
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