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were in contact in the pre-slaughter pens, and that once infection was
introduced in the abattoir it spreads to all parts, including the cutting-up
rooms and sausage making rooms. The types of salmonellae from the
pigs were the same as those from human beings in the same area. Hobbs
and others are continuing to find salmonellae in boned beef and veal from
a number of countries.
Walker found 40% of samples of fertilizers contaminated with
salmonellae belonging to types common in cases of man. The raw material
for some of these fertilizers—fish meal, bone and dried blood—is often
used for the preparation of animal food stuffs The control of meatborne
salmonellosis therefore may lie in great part in control of
foodstuffs.
It is difficult to define the importance of the human case or excreter
in the spread of salmonellosis. In the general community, cases in
contacts are not very common, though it is usual to find a number of
excreters in family contacts of a case. In hospitals cross-infection is all
too common. Spread from person to person via fomites or dust or utensils
does therefore occur in hospitals. How often it occurs in the general
population is not known.
It is evident that the control of salmonellosis must include
Reporting of human cases, so that they and their contacts may be
prevented from spreading disease; education of caterers and food
handlers in a high standard of kitchen and personal hygiene; extension
of proper refrigeration of foods; hygienic production and pasteurization
of egg products—but in addition abattoir practices need careful investigation,
as does the importance of contamination of feeding stuffs
and fertilizers.
8. About half the cases of staphylococci food poisoning were associated
with processed and made-up meals, more commonly cold ham and bacon
or brawn. In a number of instances the source of infection was one or
more food handlers. The fact that the source of infection in 8 of the 15
outbreaks is the apparently normal nose, throat or hand of the food
handler, shows that good hygiene and the exclusion from food handling
of persons with septic lesions of their skins will not by themselves ensure
the safety of such frequently implicated foods as brawn, pressed meats
and ham and bacon. The additional necessary measure is refrigeration.
9. Welchii accounted for 93 incidents. Of these, 80 were general or
family outbreaks; 59 of these were traced to the consumption of specific
foods. Fifty-four of the foods were processed and made-up meat. As in
previous years the foods most frequently at fault were re-heated meat an
meat pies.
10. Discussion. This report shows that the outstanding problem in
food poisoning is control of the spread of salmonellae. To this end
studies of eggs and egg products, meat and meat products, and feeding
stuffs and fertilizers are being made here and in other countries and are
yielding information of interest and value. It is too early yet to define the
importance of these products, but it is probable that, if they could be
protected from contamination with salmonellae in the first place or if all
products likely to be contaminated with salmonellae could be adequately
heat-treated, the incidence of food poisoning would fall considerably.