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Illness From Contaminated Produce on the Rise

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Sept. 20, 2000 (Toronto) -- Americans seeking a healthy diet are eating more farm-fresh fruits and vegetables then ever before -- but the downside is an increase in foodborne illness. Pregnant women and people with immune problems are at particularly high risk, according to a CDC report presented here at an international gathering of infectious disease specialists.

"Foodborne illness outbreaks have tripled since the 1970s," warns Cindy Friedman, MD, a medical epidemiologist at the CDC's division of foodborne and diarrheal diseases. "Bacterial causes are most common, particularly salmonella, cyclospora, E. coli, and cryptosporidium."

Not only have the number of outbreaks tripled -- to more than 10 outbreaks per year during the 1990s -- but the size of each outbreak is much larger. The average size of each outbreak was four illnesses in the '70s, but this increased to 40 illnesses per outbreak in the '90s.

"Patients are mainly women age 20 to 40 years -- a demographic usually associated with fresh-produce eaters," Friedman says. "There is nothing to suggest any difference between domestic and imported produce -- there have been outbreaks with both."

The worst culprits are sprouts -- especially alfalfa sprouts -- and fresh apple and orange juices. With sprouts, the problem is that the same process that makes the sprout grow also encourages massive growth of any germs. Fruit juices -- unless they are pasteurized -- are perfect breeding grounds for germs, which can multiply even when the juice is properly refrigerated.

"Consumers need to be aware that if you take fruit and wash it under tap water, it will reduce but not eliminate contamination," Friedman says. "New products to wash fruit also reduce -- but don't eliminate -- your risk. That's what consumers need to know."

Foodborne diseases can be dangerous, and infected people often must be hospitalized. The risk is even greater for unborn children and for people with compromised immune systems.

"High-risk individuals -- for example, pregnant women like me -- should avoid sprouts and raw juice," Friedman urges. "It's really important for consumers to find out and be aware of where the juice they drink came from."

It's not usually obvious when produce is contaminated. For example, a recent large outbreak was traced to mangos -- a fruit that is peeled before being eaten. Investigation showed that the mangos absorbed contaminated water through their stem scars during washing on the Brazilian farm where they were grown. Similarly, another recent outbreak in Connecticut and Illinois was traced to California mesclun lettuce that was washed with contaminated water.


Between the farm and the dinner table, Friedman points to many places where contamination can occur:

  • Production: Contamination can come from irrigation water or manure in the field.
  • Harvest: Poor sanitation facilities -- latrines and hand-washing stations -- contribute to contamination from workers. People who harvest produce should be considered food-handlers and take the same precautions as restaurant workers or supermarket employees.
  • Initial processing on the farm: Contamination can come from water used to wash the fruit. Open processing sheds can lead to contamination from birds, rodents, and amphibians.
  • Distribution: Contamination can come from dirty trucks or from ice used for cooling. One outbreak came from a truck used to transport raw eggs that subsequently took on a load of orange juice.
  • Final processing at the factory, restaurant, or supermarket: The longer the time since processing, the greater the chance of contamination. Cross contamination can occur from meats and other products. Improper storage temperature also can encourage the growth of bacteria.

"It makes me think more about eating these salads," Barbara E. Murray, MD, tells WebMD. "With salads, there is not a good way to eliminate contamination, but you really can't avoid them because they are so good for you. I feel more strongly about raw juices -- there are adequate ways to control these, and there are optional products such as pasteurized juice."

Murray, chief of infectious diseases at the University of Texas Medical School in Houston, warns that pregnant women should be cautious about eating cheese, milk, and certain deli products that might be contaminated with a bacteria known as listeria, which can cause a brain infection in newborns.

Friedman acknowledges that there are limits to how many foods a person can avoid. "I would eat a mango -- but I wouldn't eat sprouts or drink raw or unpasteurized juice because I am pregnant," she says.

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