But there are a lot of different food-borne diseases, and that makes for a
problem in trying to count a lot of different kinds of infections. Some
infections, like salmonella or E. coli O157 are regularly
monitored by the public health departments. Other infections, like some common
virus infections, are not counted by public health departments.
The meat industry says that American meat is the cleanest, safest meat
supply in the world. Is that the case? If so, what are we worried about?
It's hard to say our meat supply is safer than other countries' meat supply.
Each country does surveillance for food-borne disease in a different way, and
sometimes it's hard to compare the numbers.
Let's look back over 30, 40, 50 years. Has there been a trend in terms of
The one food-borne illness we have the longest run of information on is
salmonella; collection of salmonella reports began in the 1940s. At the
beginning, there were a very small number of reports, but those increased in
the 1950s, and in the 1960s, and in the 1970s. They continued to go up and up
until about 1990. In 1990 and thereafter, salmonella began to level off. And in
the last five years or so, it actually seems to be decreasing.
We don't have as good information for other food-borne infections. But we know
that several other food-borne infections, like campylobacter and listeria,
have also appeared to decrease slightly in the last few years. These modest
decreases are a lot better than the regular increases we're used to be seeing.
But we've set targets for where we want to be in 2010, and food-borne disease
is not decreasing fast enough to get us there.
Why was there a rise in these deadly pathogens prior to the 1990s?
There have been a number of important changes in the meat industry over the
last 50 years. More and more animals are raised on a single farm, so hundreds
of thousands of pigs, or hundreds of thousands of chickens, may be raised under
one roof. This gives the opportunity for pathogens to spread from one animal to
And when they are transported to slaughter, animals from many different farms
may go in the same truck or the same transport freight to the slaughterhouse.
Again, there's the opportunity for the exchange of these bacteria. As the line
speeds and the general efficiency of the slaughter plants increase, there may
also be a greater opportunity for contamination to spread from one carcass to
another. I suspect that the industrialization of our meat supply opened up a
conduit for salmonella, for campylobacter, and for E. coli O157 infections to
pass through to the consumer.
So efficiency has a downside?
If we take the meat from one animal and grind it up and make ground beef, we're
including only the bacteria from one animal. But if we take the meat from a
thousand different animals and grind that together, we're pooling the bacteria
from a thousand different animals as well.
Do you have an idea how many animals may be pooled in one burger?
I suspect there are hundreds or even thousands of animals that have
contributed to a single hamburger.
What are the public health implications of that?
This is the big challenge of E. coli O157. Even if there's a low level of
contamination in ground beef, it's possible to have an outbreak of illness that
affects many people.
Former [Agriculture] Secretary Glickman said he thought the meat supply is safer today
than it's been in a long time, but that the potential for something going wrong
is greater than ever.
That's a nice way of putting it. There have been changes in the way meat is
processed and produced within the last decade that have been important, and I
think that's part of the explanation for why we're beginning to see a decline
in salmonella. But again, because the meat is produced in large central
facilities, if something goes wrong, a lot of people could be affected at once.
How are outbreaks today different from outbreaks in 1950?
Back in the 1950s, the usual food-borne outbreak was a church social or a
wedding reception -- something where a hundred people who all knew each other
got ill. And most of them lived in the same town. Those folks would know
immediately that there had been an outbreak.
What we're seeing now [is] that there is another kind of food-borne outbreak, which
is more subtle but has much wider ramifications. And this occurs when a
food that is distributed in many different places at once gets contaminated
back at the factory, or even back at the farm. People fall ill at about the
same time, but all over the country; they don't know each other, and they don't
know that anybody else is ill. They think they're just an isolated case.
And the more centralized our food supply gets, the more there is an opportunity
for a really large outbreak. In 1993, there was a very large outbreak of E.
coli O157 affecting the western states of the United States. That was traced to
ground beef. The ground beef came from one grinding plant, but was distributed
to outlets of a Jack in the Box chain. And there were cases of E. coli all over
the West Coast. At least 750 cases were culture-confirmed, but there were
probably lots more that were never confirmed.
What did you learn from the Jack in the Box outbreak?
That outbreak was tremendously significant. It was the largest outbreak of E.
coli O157 we've had in this country. And the fact that people became ill after
ordering a hamburger -- which has got to be one of the most common events in
American food culture -- was tremendously disturbing. Before that, a number of
people in the industry felt that the problem with food-borne infections would
be solved if the customers just cooked the meat properly; if everyone just
handled the meat properly, there wouldn't be a problem.
But when you take your child or your family to a restaurant, and you order a
hamburger, you don't have much participation in how that hamburger is cooked.
So this outbreak highlighted for everybody that there was a problem in
production. And that each player in the chain of food production had an
important role to play, from those who raise the animals, to those who
slaughter it, to those who grind the meat, and to those who cook it.
How was the Jack in the Box outbreak different from previous outbreaks?
The 1993 outbreak was one of the formative events in food safety at the end of
the 20th century. It became the point of change for a lot of people in
industry, in the regulatory agencies, and for us here at CDC.
One of the remarkable things that happened was that President Clinton responded
in a very personal way. He called the parents of those children who had died to
tell them how he felt for their pain and their loss, and to tell them that he
would do whatever he could to prevent it from happening again. That sort of
personal involvement at the White House was part of the political impetus to
change the way we make our meat safe in this country, because no one in 1993
was arguing to those families or to the American public, "Oh, the meat supply
is safe enough."
It was apparent that there needed to be changes throughout the system. If we
couldn't have confidence in taking our kids for a hamburger at a fast-food
chain, what could we have confidence in? It really rocked the whole food-safety
system, and it shook up consumer confidence.
The 1993 outbreak is also when we first tried out our molecular fingerprinting
technology for E. coli O157, and demonstrated that the cases in Washington
State and the cases in San Diego and the cases in Nevada all had exactly the
same strain -- that the fingerprints matched. That gave us the confidence to
use the fingerprint method in what has become PulseNet.
How does PulseNet work?
PulseNet is a network of all the state
public health laboratories around the country, which are now fingerprinting E.
coli O157 and other food-borne bacteria on a routine basis. There are a lot of
different fingerprints for E. coli O157, and usually no two will match in a
given period of time.
But if a state public health department sees a whole string of cases where the
fingerprints match, or if we at CDC learn of cases in different states that all
have the same matching fingerprint, that suggests to us that those people have
something in common. Our investigations then focus on those people, and try[ing] to
find out what they had in common.
Using fingerprinting allows us to sharpen our analytic pencils. We can point to
cases that must be related, and others that are not related. By equipping all
of the state public health laboratories with this technology, they compare what
they find through the Internet. They can find clusters of E. coli infections
that have matching fingerprints in people who may be in 22 different states.
Because of PulseNet, we're able to identify outbreaks sooner than we used to.
And we're able to identify a new category of outbreaks that we never would have
Did you see changes in the industry's interest in food safety?
There have always been some advocates within industry for safer food. Shortly
after the western states' [Jack in the Box] outbreak occurred, Dave
Theno emerged as a powerful industry spokesman for safety of the meat
supply. He showed that a company could institute new procedures, could make
their meat safer, and could make money doing it. Since then, many in the meat
industry have embraced the concept that they are full partners in food safety,
along with the people who raise the animals, and those who cook the meat.
What sort of changes are having a positive effect on the spread of
Over the last five years, there's been a real transformation of the way that
meat inspection occurs. There's been a shift away from the visual inspection of
carcasses, and a shift towards process monitoring that reduces the amount of
contamination occurring in the plant. There have also been important changes in
the way animals are slaughtered that reduce the likelihood that the meat is
going to be contaminated in the first place.
Where did the concept of HACCP come from?
HACCP standards for the Hazards Analysis Critical Control Point evaluations. That's a piece of engineering-speak. It was developed by rocket
scientists at NASA, when the engineers who were preparing for the long space
voyages to the moon felt that it would be a total disaster if there was an
outbreak of food-borne illness on board the Apollo. They began looking at the
whole food-safety issue from an engineering point of view. They said, "What can
we do to prevent something from going wrong with the food that the astronauts
eat?" ... NASA went over all the foods that were going to be served, and
they looked for the possibilities of a germ or a pathogen getting into the
food. Then they said, "What are the critical control points to keep that from
Is HACCP working on the ground?
A modest decrease in salmonella infections and campylobacter is happening at
about the time that HACCP is coming into place in the slaughter plants. I can't
know for certain that this decrease is related to HACCP. But after years and
years of an increase in salmonella, to start seeing a decrease is an important
change. And it suggests to me that we've begun moving in the right direction.
Is modern meat in some way designed for these pathogens?
Well, nature is a wonderful thing, and there are a lot of different microbes
out there. When a new way of making a living opens up, some microbe may well
try to take advantage of it.
For example, a big part of modern food processing is refrigeration. Most
microbes won't grow in the cold, and meat won't spoil. But there turns out to
be a few bacteria that do grow at refrigerator temperatures, bacteria that find
a nice moist, cold room just the sort of place to thrive. One of these is
listeria. Listeria was not a major food-borne problem until refrigerators became a part of our food-production landscape.
Listeria has found a home in the processing plant itself, in the cold room, in
the nooks and crannies, in the mists and fogs that drip off the chiller
equipment. If something drips off the ceiling onto hot dogs or deli meat, they
can be recontaminated with a new organism that they didn't originally have. If
the meat is then packaged up and stored in a refrigerator, that listeria can
slowly grow in the refrigerator. And now there's a problem.
Have advances in technology created new problems?
Well, I guess there's a law of unforeseen consequences. When a new technology
comes in, there may be unanticipated ecological homes for pathogens that we
didn't used to recognize as a problem.
Given that, what do you do differently when you go to the grocery store to
buy your meat?
There are a number of things that the concerned consumer can do. One is to look
for evidence in a restaurant or a grocery store that the people who work there
have been trained in food safety. I'd rather buy my meat from people who
understand the basic principles of food safety. The meat I buy is probably no
different than the meat that lots of people buy. But I bag it separately, and I
handle it carefully, and I cook it thoroughly.
Do you cook your burgers really well done?
Yes, I do. And sometimes I even buy precooked burgers. We don't yet have
irradiated ground beef for sale in this part of the country, but it is for sale
in other parts of the country. If it were available, I would buy that.
You support the irradiation of meat?
I think irradiation of ground beef and of other high-risk meats is going to be
a really important public health tool, just like the pasteurization of milk has
been. The irradiation process that's used for meats does not induce any
radioactivity in the meat. It doesn't introduce any important changes in the
meat at all, except that it kills the bacteria that might be present. So I'm
not concerned about the safety of the meat after it's been irradiated.
Explain why ground beef is more at risk than a sirloin steak.
With a steak, you're basically looking at the product of one animal. Ground
beef often is the mixture of hundreds or even thousands of animals. And if
even one of those were a source of E. coli O157, it might be in the final
The second thing is that when meat becomes contaminated during slaughter,
contamination usually occurs on the outside of the carcass, on the surface of
the meat. And when you cut a steak from that, the contamination is present just
on the surface of the steak. The surface is what hits the frying pan, so that
surface is cooked.
But when we grind meat, we take what was on the surface, and we bring it to the
inside, and we mix it all around. A ground-beef patty is essentially all
surface all the way through. What is in the middle of the hamburger may be what
was on the outside of the animal. That's why you have to cook a hamburger all
the way through -- because the contamination may be all the way through. ...
Given the problems that centralization brings, some people say we need to go
back to the smaller producers. Others say we need more technology to solve the
problem. What do you think?
Food can be produced safely in a number of different ways, and I think that the
big industrialized food supply of this country is probably what we need in
order to have enough to eat. There are an awful lot of us, and the efficiencies
of that food industry are what keep us fed everyday. But large-scale food
production means we need to have large-scale safety engineered in. And I do
think we need new technology in the large-scale food production to really be
confident of the safety of our food supply.
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