More than 335 people in Washington, California, Oregon, Idaho, New Mexico, Arizona and Alaska have had confirmed or suspected cases of the bacterial illness, characterized by severe diarrhea, nausea, fever and stomach cramps.
At least 122 laboratory-confirmed cases have been reported in Washington, including 76 in King County. As many as 32 other cases statewide are suspected.
No deaths have been reported, but at least two Washington residents have been hospitalized, said Dr. Marcia Goldoft, an epidemiologist for the state Department of Health. "The peak of the outbreak is clearly over. But we're still emphasizing to people with any diarrhea to be very careful with their hand washing," Goldoft said. "It's safer that they not be preparing food at all." Patients with shigellosis typically have diarrhea for about a week, but some cases last up to four weeks.
The first cases were reported in mid-January. The outbreak is linked to several products of Senor Felix Gourmet Mexican Foods of Baldwin Park, Calif. The products were recalled in January after the federal Food and Drug Administration warned consumers not to purchase any five-layer dip sold under the following brand names: Senor Felix's Five-Layer Party Dip, Delicioso Five-Layer Dip, Trader Joe's Five-Layer Fiesta Dip or the Carryout Cafe Mexican Fiesta Party Dip Five Layer.
The dips were sold locally at Costco, Trader Joe's, Puget Consumers Co-op, QFC, Thriftway, the Red Apple Market, Zupan's and Homegrocer.com. Goldoft said the outbreak is one of the largest ever in Washington state. Health officials have been swamped with calls, she said.
The actual number of cases is likely double the confirmed cases, she said, because not all patients see a physician and not all cases are laboratory-analyzed. A class-action lawsuit alleging negligence by the dip company was filed last week in King County Superior Court. California and federal health officials said the specific source of the outbreak has not been determined. They would not release details of the investigation. However, Janet Anderberg and Bert Bartleson, food-safety specialists for the Washington Department of Health, said they have heard from investigators that food handlers in the Senor Felix manufacturing plant were not likely the source.
All have been tested for the disease - some as many as three times - and none has tested positive, they said. Bartleson and Anderberg said the investigation for now is focusing on cilantro and green onions, both used in the dip. As fresh produce, neither was subjected to heat, which kills bacteria. And cilantro was implicated in an outbreak in another state, they said. "This is just a theory. They're looking at many ideas," Anderberg said.
The bacterium shigella causes shigellosis. It is transmitted by human feces, typically after someone has used a toilet and not washed his hands before handling food. Or it could be transmitted when uncooked food, such as produce, is washed with contaminated water. The disease affects people with weaker immune systems, including small children and the elderly, most severely.
Goldoft said almost all the Washington cases have been in adults or adolescents. Goldoft said epidemiologists from Public Health-Seattle & King County realized they had a significant outbreak Jan. 21 when several sickened people they interviewed said they had attended the same baby shower and eaten the dip.
The officials called California health officials, who confirmed several cases there. Other recent major outbreaks of food-borne illness in Washington state include a 1993 epidemic of E. coli O157:H7 bacterial illness stemming from tainted Jack In The Box restaurant hamburgers that sickened 500 people and killed three children; a 1993 salmonella outbreak in Pierce County that sickened 166 children at a summer camp; a 1994 salmonella outbreak in Tacoma stemming from tainted turkey that sickened 297 people.
Another E. coli O157:H7 outbreak in 1996 linked to Odwalla apple juice sickened 66 people in several Western states and killed a Colorado girl.