[Emerging Infectious Diseases * Volume 3 * Number 4 * October - December 1997]


Historical Overview of Key Issues in Food Safety

E. M. Foster
Madison, Wisconsin, USA
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      Foodborne transmission of pathogenic and toxigenic
      microorganisms has been a recognized hazard for decades. Even
      half a century ago we knew about the dangers of botulism from
      underprocessed canned foods; staphylococcal poisoning from
      unrefrigerated cream-filled pastries, sliced ham, meat, and
      poultry salads; and salmonellosis from infected animal
      products. Despite new protective measures, changes in
      preservation techniques and failure to follow recognized
      procedures have created new dangers. Moreover, we now recognize
      new organisms that can cause foodborne illness--Listeria
      monocytogenes, Escherichia coli O157:H7, Campylobacter jejuni,
      Vibrio parahaemolyticus, Yersinia enterocolitica, and others.
      Controlling these organisms will require widespread education
      and possibly new regulatory initiatives.

When I was growing up on my parents' farm in East Texas, we never thought
about food poisoning or unsafe food. The only foods we bought were sugar,
salt, flour, and oatmeal; everything else we produced and preserved on the
farm. My mother spent all summer canning fruits and vegetables for winter.
We had no refrigeration; we cured our own meat and drank raw milk. But I
never heard of botulism, staph poisoning, or salmonellosis or perfringens
poisoning until I studied bacteriology in college. Only then did I wonder
how we survived with no refrigeration in a hot climate. Finally, the answer
came to me. We just did not give the bacteria time enough to develop so
they could hurt us. Leftovers from breakfast--hot biscuits, eggs, ham, bacon
or sausage, oatmeal, coffee or milk--went right out to the chickens. Lunch
leftovers--biscuits, cornbread, vegetables, or fried chicken--were saved for
a cold supper 4 or 5 hours later. Any food left went to the pigs. The
bacteria had only a maximum of 3 or 4 hours to grow, and that usually is
not enough. I survived and went on to study food microbiology, which
included what was known then about food poisoning. The guru of food
poisoning in those days was professor Gail M. Dack at the University of
Chicago. Dr. Dack was a protege of Professor E.O. Jordan, who in 1917
published a 107-page book entitled Food Poisoning. Dr. Dack took over the
book and published his first version of Food Poisoning in 1943. In 1949 and
1956, subsequent editions appeared in which certain truisms became
apparent.

Botulism was considered a problem of canners, both home and commercial.
Thus, adequate heat processing would seem to solve the problem. Perhaps it
did for the canner, but now we know that heating will not eliminate all
botulism. Many foods, including salmon eggs, smoked fish, garlic in oil,
vacuum packaged lotus roots, and baked potatoes, can support growth and
botulinum toxin formation if the storage temperature is suitable.
Similarly, we thought staphylococcal poisoning was limited to cream-filled
pastries and cured ham. In recent years, outbreaks of staphylococcal
poisoning have been traced to cheese, whipped butter, ham salad, fermented
sausages, and canned corned beef. We now know how to prevent staphylococcal
poisoning, but not all food handlers understand and fully comply with the
appropriate control measures.

Salmonellosis was once thought a problem with meat from infected animals.
Now we know that a variety of food products can serve as vehicles of this
disease. As early as World War II, we found that dried eggs from the United
States could transmit this disease to our British allies. Thousands of
cases of human salmonellosis in the United States and other industrialized
countries have been transmitted by ice cream, chocolate, potato salad,
cheddar cheese, raw milk, black pepper, pate, aspic, ham, pasteurized milk,
and drinking water.

Clostridium perfringens, known since the 1940s, causes a problem only when
there is gross temperature abuse of cooked food. Clostridium botulinum,
Staphylococcus aureus, C. perfringens, and the salmonellae were well known
in Dr. Dack's day, although the food vehicles might have changed. Not so
well known were many of the organisms that preoccupy us today. For example,
we used to think of Escherichia coli as merely an indicator organism that
suggested insanitary handling. Now we know forms of E. coli can kill.
Thirty years ago, Listeria monocytogenes, Campylobacter jejuni, Aeromonas
hydrophila, Plesiomonas shigelloides, Vibrio parahaemolyticus, and Yersinia
enterocolitica were not known; now these are well-established foodborne
pathogens that we must control.

Although not part of a historical overview, other key issues deserve
attention during this meeting. For example, we once thought that fresh,
uncracked eggs were essentially sterile and safe to eat. We did not
recognize the ability of Salmonella Enteritidis to invade the laying hen
and thereby the yolk of an egg. An outbreak of S. Enteritidis at a Chicago
hotel taught us not to rely on the safety of eggs merely because the shell
was intact. S. Enteritidis in shell eggs is still a serious health problem
and a growing concern to egg and poultry producers.

Of equal, if not greater, concern is Salmonella Typhimurium strain DT 104.
Widely distributed in cattle herds of England, Scotland, and Wales, this
organism is resistant to several antibiotics, including ampicillin,
chloramphenicol, streptomycin, sulfonamides, and tetracycline. Between 1990
and 1995, the number of S. Typhimurium DT 104 isolated from humans in
Britain increased from 259 to 3,837 per year--a 15-fold increase. Moreover,
the percentage of drug-resistant isolates increased from 39% in 1990 to 97%
in 1995. S. Typhimurium DT 104 has been isolated in the United States from
sheep, pigs, horses, goats, emus, cats, dogs, elk, mice, coyotes, ground
squirrels, raccoons, chipmunks, and birds. American egg and poultry
producers are concerned about its entry into U.S. poultry flocks. S.
Typhimurium DT 104 infection in humans has been associated with the
consumption of chicken, sausage, and meat paste as well as with the
handling of sick animals. More than one-third of the patients have required
hospitalization, and 3% have died; these figures are very unusual for
ordinary Salmonella infections and indicate serious problems ahead.

Address for correspondence: E. M. Foster, Professor Emeritus, Food Research
Institute, University of Wisconsin, Madison, WI 53706 USA; fax:
608-263-1114.
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Emerging Infectious Diseases
National Center for Infectious Diseases
Centers for Disease Control and Prevention
Atlanta, GA