Bagged salad mix vexes food investigators
Food safety experts are beginning to grumble that an investigation into the latest food-borne illness is taking too long to find the exact source of the outbreak. Two states, Iowa and Nebraska, have reported they believe the outbreak is linked to prepackaged, bagged salad mix, but others aren't so sure.
The number of victims in the national outbreak of cyclospora, a food-linked diarrheal disease, rose to 397, with illnesses reported in 16 states, the Centers for Disease Control and Prevention reported.
The CDC said it is working to determine whether the possible link to bagged salad mix applies to cases in other states as well.
The Food and Drug Administration “can't speak to an ongoing investigation,” said FDA spokeswoman Theresa Eisenman.
“With 390-some people ill, you'd think it would be fairly easy to triangulate the trace back” to the food causing the illnesses, said Dave Gombas, senior vice president for food safety with United Fresh Produce Association, a trade group in Washington. “So the fact that FDA and CDC aren't going along with Iowa and Nebraska gives me pause.”
Cyclospora, an intestinal illness, is caused by a microscopic parasite. It is transmitted when feces enter the food or water supply and are consumed. Besides diarrhea, symptoms can include fatigue, anorexia, bloating, stomach cramps, vomiting, muscle aches and a low fever. It is treated with antibiotics.
At least 22 people in five states have been hospitalized.
Iowa's public health system first caught the outbreak on June 25 when Michael Last, a parasitologist at the State Hygienic Laboratory at the University of Iowa in Coralville, recognized the parasite in a stool sample sent by a physician for testing.
He is “a good, good, good microbiologist,” said Patricia Quinlisk, Iowa's state epidemiologist.
The parasite is rarely seen in the United States. “We haven't had a major outbreak from cyclospora in almost a decade,” said Caroline Smith DeWaal with the Center for Science in the Public Interest in Washington. Her database shows the most recent large outbreak was in Florida in 2005, where 592 people were sickened with contaminated basil. The nation's largest-known cyclospora outbreak was in 1996 when raspberries from Guatemala sickened 1,465 in several states, she said.
Iowa health workers established that about 80 percent of the people who'd gotten sick had eaten the same brand of prepackaged salad mix containing iceberg and romaine lettuce, carrots and red cabbage. Packaged lettuce has a short shelf life, so by the time investigators began interviewing people “the bags were long gone,” Quinlisk said. That means there wasn't anything for them to test to see which of the mix's four ingredients was responsible.
The last person Iowa tested got sick on June 28. State officials believe the tainted lot of salad mix is gone from store shelves and the outbreak is waning there. What's going on in other states is difficult to say because “their epidemiology looks a little different,” Quinlisk said.
It wouldn't surprise her at all if there were more than one outbreak going on, Quinlisk said. “When we look at the data from other states, the people who are getting ill are not necessarily the same as we saw; they're not getting sick at the same time.”