More than 500 people who ate at a Chi-Chi's restaurant in early October fell ill with hepatitis A, an infection that attacks the liver. Symptoms may not appear for up to 50 days following exposure, so health officials fear more illnesses could emerge in the coming weeks. Three people have died.
Nearly 9,000 people, including people who ate or worked at the now-closed restaurant and their families, have been given immune globulin shots, which can prevent illness if given within two weeks of exposure, says state health department spokesman Jay Pagni.
It's not certain what caused the outbreak, but suspicion has focused on green onions, or scallions. Hepatitis A outbreaks in September in Tennessee, Georgia and North Carolina were linked to raw or undercooked green onions; at least some of them were traced back to Mexico, says Bob Racket of the Food and Drug Administration.
Raw produce can become contaminated by being rinsed with dirty water or handled by an infected person, he says.
"We always recommend that produce be washed," he says, "but washing is no guarantee. People who are concerned (about a food) should cook it."
Hepatitis A is passed by what doctors call the fecal-oral route, meaning someone who is infected can transfer the virus to food or other people if they don't wash up after using the bathroom.
Symptoms, including fatigue, nausea, diarrhea, fever and jaundice, may appear in two to seven weeks, and there is no medication to treat it. Many people, especially children, have only mild illness, but infection can be dangerous to people with liver disease or immune disorders. The Centers for Disease Control and Prevention says about 100 people a year die of liver failure caused by hepatitis A. Most victims recover in a couple of months and are immune thereafter.
About a third of the U.S. population already has had hepatitis A, says Anthony Fiore, an infectious disease doctor at the CDC.
"We might have gotten it as children," Fiore says. "It's a common disease, but it was a lot more common when those of us who are adults were children."
Though only a fraction of cases are reported, the CDC estimates there were as many as 93,000 cases in 2001. Yet, it's a "totally preventable disease," says Philip Rosenthal, professor of pediatrics and surgery at the University of California-San Francisco and spokesman for the American Liver Foundation.
Vaccines, which provide long-term protection, have been available since 1995. In parts of the country, mainly in the West where hepatitis A vaccine is given as part of childhood immunization programs, infection rates have dropped 86%, he says.
It's no longer necessary to travel to exotic locales to encounter international bugs, says epidemiologist Craig Headberg, professor of public health at the University of Minnesota. "Our produce-distribution systems have created opportunities for exposing people to a lot of organisms that have historically been viewed as being travel-associated infections," he says.
Produce imported into the USA is held to the same standards as homegrown, Racket says. Last summer the FDA reported it had increased its imported food inspections more than fivefold as part of post-9/11 food-security efforts. Food growers, domestic and foreign, are given FDA guidelines on safe practices, and the agency conducts training programs to help growers improve safety practices.
As a spot-check, the FDA in 1999 began a program to test samples of domestic and foreign-grown produce for three common food-borne pathogens: salmonella, shigella and a strain of E. coli. The tests found no difference between imported and domestic-grown produce, Racket says.