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25
Examination of Milk
During the year, eight samples of milk were submitted for methylene blue and phosphatase tests,
all of which were satisfactory.
Milk Supplies—Brucella Abortus
Brucella Abortus is the organism associated with contagious abortion in cattle, and its transmission
to man occurs through drinking raw milk. As almost the entire supply of milk sold and consumed in
Westminster is heat-treated, no tests to determine the presence of this organism were carried out during
the year.
Food Poisoning
During the year, 159 cases of persons suffering from food poisoning or suspected food poisoning
came to the attention of the Health Department. Of this number 24 were individual cases.
Seven persons were ill some 5 to 10 minutes after consuming a steak and kidney meal and the
evidence pointed to metallic poisoning. A vomit specimen revealed traces of zinc and it is believed
that a member of the family may unwittingly have placed some unidentified substance in the stewing
saucepan.
Three persons were reported as suffering from food poisoning after having eaten canned pate de
Foie Gras; staphylococcus aureus was isolated from one stool specimen. Phage typing confirmed
the organism as the one causing the food poisoning, and the evidence suggested that this was present
in the tin before opening.
A husband and wife became ill after eating deep frozen chicken at home. The symptoms were
suggestive of staphylococcal intoxication and it is interesting to note that the wife had been found to be
carrying a staphylococcus aureus organism associated with food poisoning during the investigation
of an outbreak the previous year.
Four persons became affected with acute gastro-intestinal symptoms after consuming a meal consisting
of stewed steak and potatoes in a restaurant. A sample of steak taken several days after the
occurrence was positive for Clostridium welchii, and it appeared that this organism had survived
the initial stage of the cooking process. Instructions were given to the proprietor regarding the importance
of temperature control in preventing the multiplication of organisms in cooked meat dishes.
Orange sauce used with roast duckling was believed to be the vehicle infecting five persons who were
ill. The symptoms suggested Clostridium welchii which was supported by bacteriological reports on
faecal specimens from three of those affected.
Six persons after eating a meal which included shepherd's pie, complained of diarrhoea and
abdominal pain. Four were found to be excreting Clostridium welchii organism. It is probable that
his organism with its resultant toxin, survived the cooking process.
Between eight and twenty hours after a dinner at a restaurant, some 70 persons were taken ill out
of 780 people who had attended. Three specimens positive for Clostridium welchii were obtained.
No food remained from the suspected meal, but a thorough investigation was undertaken at the
premises concerned, without conclusive results.
A brother and sister taken ill with symptoms of vomiting and diarrhoea were found to be suffering
from salmonella typhimurium infection. The children had recently returned home from holiday, and
it was believed that infection was probably contracted before leaving the holiday address. The Medical
Officer of Health for the area concerned was informed, but the origin of the infection was not determined.
Fourteen members of a hospital staff were ill with vomiting and diarrhoea after a meal which included
cold roast beef. Salmonella Panama was isolated from a faecal specimen, and it is possible that the
large size of the beef joints used may have allowed survival of pathogens or toxins.
Nine members of a day nursery staff were affected with symptoms associated with food poisoning.
Faecal specimens from those affected disclosed the presence of Salmonella Heidelberg, but the origin
of the infection could not be determined.
Thirteen persons were involved in three separate occurrences over a period of three days in which
the food consumed was barbecued chicken. The evidence suggested that a non-specific organism of
unknown origin had gained access to the equipment in use, and the temperature and time factor involved
had given rise to a heavy growth of this organism with the resultant toxin.
Statistics relating to these outbreaks, and the causative agents, where discovered, are given in
Table 26, page 63.