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in contact with cattle feces. People pick up E. coli O157:H7 infections from direct contact with feces, from foods and water that have come in contact with feces, or from infected people who shed it in their feces and pass it along from unwashed hands—which is why hand washing is so important as a control measure. Uncooked foods derived from cattle (raw hamburger, for example) are the origin of most E. coli O157:H7 outbreaks.17 As we will see, fruits and vegetables that have come into contact with cattle feces or with contaminated raw meat also have become common sources.

TABLE 4. Recommendations for reducing the risk of infection from E. coli O157:H7

Cook meat—especially ground meat—thoroughly to 160°F.*

Do not drink unpasteurized milk or juices.

Wash fresh fruits and vegetables thoroughly.

Wash hands thoroughly after handling animals, especially cattle, deer, goats, dogs.

Wash hands thoroughly after changing children’s diapers or providing care to children or adults with diarrheal diseases.

Do not fertilize fruits or vegetables with manure from ruminant animals.

Avoid swimming in lakes or ponds used by cattle.

Do not drink surface water that has not been chlorinated, boiled, or otherwise treated to eliminate pathogens.

SOURCE: Buchanan RL, Doyle MP. Food Technology 1997;51(10):69–76.

*Bringing a food to 155°F is sufficient to kill these bacteria; recommended cooking temperatures provide a 5°F margin of safety. Pasteurization brings liquids to scalding temperatures (about 140°F) for short times; this process destroys most bacteria and delays the growth of those that survive.

E. coli O157:H7 is considered newly emergent because its recognition is so recent. The earliest case seems to have occurred in 1975, but the first reported outbreak occurred in 1982. Infections have now been observed in 30 countries on six continents. Outbreaks are increasing in frequency; there were 6 in 1997 but 17 in 1998. The infections are exceptionally serious; 82% of people infected with E. coli O157:H7 see a physician, 18% require hospitalization, and the mortality rate is 3–5%.18 How E. coli O157:H7 emerged and spread throughout the food supply is a subject of considerable speculation. The most reasonable explanation involves the profound changes in society and food production that have taken place in recent years, matters to which we now turn.

REVOLUTIONIZING THE FOOD SYSTEM

Most of us imagine that the rapid advances in science and medicine of the last century would make microbial diseases a thing of the past, and we would hardly think agriculture to be a cause of medical problems. But alterations in the ways we produce food, choose diets, and live our lives have created conditions that favor the spread of pathogens into more foods consumed by more people. These changes foster the emergence of microbial pathogens that resist heat, cold, acid, and other preservation methods. They also encourage pathogens to develop resistance to treatment with antibiotic drugs. Refer back to figure 2 in the introductory chapter to see how the food system has changed from one based primarily on locally raised meat, fruits, and vegetables to one in which commodities like StarLink corn travel great distances—across many states and between different countries—before reaching supermarkets. Table 5 summarizes some of the developments in food production, consumer preferences, and demographics that favor foodborne illness. Because such developments involve consumers as well as food companies, they illustrate why food safety has to be a shared responsibility but also why it is difficult to determine accountability when outbreaks occur.

TABLE 5. Modern developments in food production practices, dietary preferences, and demographics that favor the emergence and spread of foodborne illness

Food production practices

Concentration and consolidation of production

Transportation across long distances

Centralized processing of food from many sources

Use of low-dose antibiotics to promote animal growth

Use of low-fiber animal feeds