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A review of the position on the morning of 27th September showed (a) that over
150 persons were affected and three of them so severely as to necessitate removal to
hospital (b) that the rate of return to work of the affected persons was slow and that
many who had returned to work were not fully recovered (c) that salmonella typhimurium
had been found in 15 faecal specimens from affected factory staff and (d) that
the same germ was present in faecal specimens from four of the canteen staff. After
consultation with the works' medical officer the firm was advised to suspend temporarily
from work all canteen staff and the appropriate notices under the Public Health
(Infectious Diseases) Regulations, 1953, were issued to the canteen staff known to be
harbouring salmonella typhi-murium. The firm agreed to pay wages during suspension
to the canteen staff subject to them submitting specimens as required for bacteriological
examination. Three negative results at not less than two day intervals was
agreed as the basis on which return to work in the canteen would be permitted.
By 28th September a final list of the names and addresses of all affected persons
was available. The total was 195 and a letter was sent to each informing them of the
nature of the outbreak, advising them to inform their own doctors and stressing the
need to wash the hands thoroughly, after using the water closet, to prevent the spread
of infection. On the same day arrangements were made for a firm of caterers to take
over the canteen. Despite the talks to them some of the canteen staff appeared not
to appreciate the seriousness of the outbreak, resented their suspension from work and
wrote or called at the Health Department to express their views.
At the end of the investigation salmonella typhi-murium had been found in 6
members of the canteen staff and in 18 affected factory workers. No member of the
canteen staff admitted to a recent gastro-intestinal illness. A search of the staff
records showed that one had suffered from gastro-enteritis in 1949 and 1951. No
bacteriological investigation of these illnesses had been carried out, but as she was
severly affected by the food poisoning it is most unlikely that she was a carrier.
Another admitted that she had provided faecal specimens in 1953, but an enquiry to
the Medical Officer of Health of the district concerned, revealed that the
investigation arose from contact with dysentery and that no pathogenic organisms were
found. During the follow up of canteen staff it was learned that an out-break of
diarrhoea had occurred in the household of another. Faecal specimens from all in
the house contained salmonella typhi-muruim, but other than a statement that the
diarrhoea started "at the same time as the food poisoning" the date of onset could
not be fixed.

The suspension from work in some cases was longer than it might have been because
of difficulties and delays in obtaining specimens, but in one only of the canteen
staff was the carrier state persistent. Apart from the time lost from work by the
canteen staff this outbreak of food poisoning resulted in a loss of over 600 working
days by the affected members of the factory staff.
On 27th October the canteen staff took over the catering again, but prior to
this they were given a course of three lectures on food hygiene. A report was submitted
to the firm concerned and advice offered as to the action that should be taken
to reduce the chances of further outbreaks of food poisoning.
The nature or source of the outbreak at the Teachers' Training College was not
found. in December it was reported that at one school a number of pupils and staff
had suffered from vomiting and diarrhoea. Bacteriological investigation of school
meals and specimens from adults and children failed to reveal any food poisoning germs.
Enquiries showed that a similar illness occurred among other members of the families
of the affected persons and that in varying degree three other schools in the same
district had been affected; Vomiting was the most prominent symptom and the illness
appeared to be of the nature of ""epidemic winter vomiting" which was reported here
in 1954.
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