The recent hepatitis A outbreak.

The recent hepatitis A outbreak.

The recent hepatitis A outbreak.

Health and medicine explained.
Nov. 21 2003 1:57 PM

Dirty Rotten Scallions

Why the recent hepatitis A outbreak can be traced to Third World produce.

People in Beaver County, Penn., are already familiar with the downside of the global economy. The steel mills that once employed tens of thousands have long since closed, unable to compete with low-cost labor in Asia. And now the residents of the former steel capital are enduring another effect of expanding world trade—the biggest hepatitis A outbreak in U.S. history: at least 540 cases and three deaths.

Hepatitis A is a virus usually transmitted by human fecal matter on food and is endemic in many poor parts of the world. Symptoms, which include jaundice, fever, and fatigue, can range from mild to deadly. This outbreak apparently stemmed from green onions—also known as scallions—served on tacos and other dishes at the Chi-Chi's restaurant in the Beaver Valley Mall.

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More than half the green onions consumed in the United States are grown in Mexico. Investigators believe that the batch of onions that made its way to Chi-Chi's came from three Mexican growers implicated in smaller outbreaks in Georgia and Tennessee that occurred in September. They also suspect that questionable food-handling practice in that particular restaurant caused the virus to spread to so many people. This incident may seem isolated, but it highlights a rising problem that is only going to grow worse: Produce grown in developing countries is bringing the diseases of those countries to America.

How is this happening? The endless quest for cheaper land and labor pushes even more of our agriculture into other countries. How many oranges still grow in Orange County, Calif., or Orange County, Fla., once full of endless groves and now home to Disneyland and Disney World, as well as vast suburban sprawl? In addition, Americans are heeding the sound advice of health authorities to eat more fresh fruits and vegetables, and they want a variety of choices at any time of year. The result: More crops are grown in hot distant places and then shipped stateside. Indeed, at certain times of the year, more than 70 percent of the fresh produce in the United States comes from Mexico.

The problem, as anyone who has worked on this issue knows, is that many countries that grow produce for the United States—such as Mexico, Guatemala, and the Philippines—have limited sources of sanitary water, including the water used to irrigate the crops. As a result, a great deal of freshly picked produce can pass through streams of untreated waste before making its way to the United States. Plus, field hands often have no toilet facilities or clean water to wash their hands. Of course, many growers in Mexico and other countries strive to keep their fields hygienic, and migrant workers can bring diseases when they come to pick crops in the United States, too.

Estimates of cases of food-borne disease in the United States range from 6.5 million to 81 million annually, and yet most of the time these illnesses escape public attention. An individual or a group gets knocked out by severe gastrointestinal symptoms but usually recovers. Most commonly, the culprit is E. coli, the ubiquitous bacteria in the human gut that often causes travelers' diarrhea. With the exception of the strain called 0157:H7, often transmitted by undercooked meat and by lettuce, most varieties of E. coli that cause disease remain unknown. This means that even if someone is sick enough to go to the doctor chances are nothing will be cultured, and unless some alert health officials notice a connection between cases, even large outbreaks can go unrecognized. Of course, E. coli is not the only dangerous microbe to hitch a ride on our food. Bacteria such as salmonella and shigellosis and a parasite called Cyclospora (made famous by outbreaks caused by berries from Guatemala) are among the many other germs all striking with increasing frequency.

For reasons buried deep in legislative history, the Food and Drug Administration is responsible for assuring the safety of imported produce, and it faces an overwhelming task: Mexico, for example, shipped 1.9 billion pounds of tomatoes alone to the United States last year. In a press release titled "Tips to Prevent Food Borne Illness This Holiday Season" disseminated this week, the agency offers advice such as "Wash hands and food-contact surfaces often. Bacteria can spread throughout the kitchen," and "Don't cross contaminate—don't let bacteria spread from one food to another." That's fine, except it fails to take into account the fact that that Americans increasingly get their meals in restaurants where food handlers might not be as careful as people in their own homes, and that organisms like Cyclospora cannot be washed off. And buying organic will not help; organic foods, because of the way they are grown, in manure, are often exposed to even more microbes. The health benefits of fruits and vegetables are so great that we should continue to eat them, but it's always advisable to wash them first (though, again, this is not a foolproof solution). Risk of food-borne germs is something we'll just have to live with. Like the residents of Beaver County, we've all become gastronomic travelers in the global economy.

Robert Bazell is chief science correspondent for NBC News.