From the publishers of the New England Journal of Medicine
Any savvy traveller knows the rules: On trips to a developing country, avoid the local fruits and vegetables. If you eat salads, juices, or produce that isn't peeled or cooked, you risk a bout of nasty stomach upset.
Now it seems the same rules apply even to trips to your local supermarket and favorite hometown restaurant. Over and over, Americans are hearing about local outbreaks of gastrointestinal disease traced to raw fruits or vegetables contaminated with dangerous microorganisms.
Several months ago, nearly 200 Michigan schoolchildren developed stomach pains and jaundice and were found to have hepatitis A. Epidemiologists traced their illness to a school treat of strawberry shortcake. The dessert was made from frozen strawberries that had been grown in Mexico, processed in southern California, and contaminated with the hepatitis A virus somewhere in their travels.
Last summer, an outbreak of infectious diarrhea also was caused by imported berries: Raspberries from Guatemala were identified as the vehicle that infected North Americans from New York to Texas to Toronto with an unusual diarrhea-causing parasite called Cyclospora cayetanensis. Again this year, cases in five states seem linked to raspberries from Guatemala.
But produce need not be imported to be dangerous. Last fall in the Western US, dozens of cases of bloody diarrheaand one deathwere traced to a batch of organic apple juice made from California apples that had somehow been contaminated with the virulent bacteria E. coli 0157:H7.
E. coli 0157:H7 is the same microbe that contaminated undercooked hamburger meat in the infamous Jack-in-the-Box outbreak of 1993 that resulted in the deaths of four children. It also caused illness traced to contaminated lettuce in 1995.
What may appear to be an increase in produce-related outbreaks has been ascribed to a number of factors, including far more produce from around the world entering the US, more widespread use of national-brand packaged and processed foods, and scientific techniques that enable better tracking of outbreaks. The outbreaks have concerned not only consumers but also federal officials, who now estimate that up to 33 million cases of food-borne illness occur in the US yearly, resulting in about 9,000 deaths and an annual expense of some $3 billion.
President Clinton recently proposed that $43
million of the 1998 budget be used to improve food safety by expanding surveillance and
diagnosis networks. Proposals for reorganizing food-protection agencies are also afoot.
Until such steps have an impact on the safety of your supermarket produce section, how can
you ensure that you and your family will not become part of the worrisome statistics?
The Physician's Perspective
In fact, it is easy enough to reap the benefits of raw fruits and vegetables while avoiding their risks by taking just a little extra care with your food-buying and preparation habits.
The produce-associated outbreaks described above may appear all quite differentthey involved different kinds of organisms (parasites, viruses, bacteria) contaminating different kinds of fruits and vegetables (berries, apples, lettuce) that were grown in different parts of the world and prepared in different ways.
Even so, these incidents have enough in common to easily deduce a set of rules for avoiding similar disasters. Plainly speaking, all the outbreaks occurred because of fecal contamination. At some point in the growth and processing of the implicated fruit or vegetable, human or animal feces contaminated its surface. It may have been contaminated water used to irrigate a berry patch in Guatemala, or manure from a California cow infected with E. coli 0157:H7 that was spread underneath an apple tree and touched the falling fruit. It may have been the dirty hands of a worker ill with hepatitis A, picking fruit in a Mexican berry patch without adequate bathroom facilities. However it happened, the microbe grew whole colonies on the surface of the fruit or vegetable, which may have traveled thousands of miles and arrived on someone's plate without being washed clean.
Thus the first and most important rule for preventing foodborne disease: Scrub your produce carefully. Then scrub your cutting board with soap and water, and then scrub your hands. Even without soap, a good rinse can rid fruit and vegetable skins of most harmful organisms. It may not completely eliminate the risk of cyclospora in the tiny crevices of berries, but it should decrease the risk. If the skin of a piece of produce is broken, toss it out: Organisms may have crawled into the pulp beyond the reach of your scrubbing. After washing, refrigerate all cut or peeled fruits and vegetables.
What about liquids like the tainted California apple juice? That question perplexed French scientist Louis Pasteur in the 19th century when he was trying to eradicate milk-borne disease. Pasteurization was his solutionand it still is today.
Briefly heating beverages and then rapidly cooling them can kill most feces-associated bacteria and make even contaminated drinks safe. The California juice was unpasteurized: Some raw food aficionados eschew pasteurization, arguing that it detracts from taste and nutritional content. While these issues are certainly debatable, the health benefit of pasteurization is not. Avoid unpasteurized foods. If you feel like buying raw cider at a roadside stand, go right aheadbut if you want to be certain of its safety, boil it before drinking.
Finally, what to do about produce served in a restaurant or at a party or mass-prepared school lunches? These answers are less clear. Any item that is clearly the worse for wear (slimy lettuce or gritty, dirty fruit) should be avoided, as should any item that has been implicated in a current outbreak.
Fruits and vegetables are essential to a healthy diet and needn't be shunned. But if you want to be absolutely sure to steer clear of produce-associated illness, you might elect to do most of your raw fruit and vegetable eating at home, where you can make sure that thorough washing precedes serving and eating.
Abigail Zuger, MD, a specialist in
infectious diseases, is an attending physician at Beth Isr'el Medical Center in New York.
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