Editor's note: This article was updated after initial publication to include information from new CDC and FDA releases.
Health departments in Iowa and Nebraska today announced that the source of Cyclospora infections in the two states is prepackaged salad mix, but federal health officials said they are working to determine if the findings apply to cases in other states and are looking into other possibilities.
The two states were the first to report Cyclospora illnesses and between them have 221 cases.
In a statement today from the Iowa Department of Public Health (IDPH), Steven Mandernach, chief of the Food and Consumer Safety Bureau of the Iowa Department of Inspections and Appeals (DIA), said epidemiologic and food history interviews with sick patients point to a bagged salad mix containing iceberg and romaine lettuce, carrots, and red cabbage.
The IDPH said the DIA's investigation found that about 80% of the sick patients had been exposed to the same prepackaged salad mix that came from a single source. Mandernach said the salad mix is no longer in Iowa's food supply chain, and he told the state's residents it was safe to continue eating salads.
He said that because of the delay between eating the contaminated food and getting sick, there were no products on shelves to be tested for parasites, and most of the investigation focused on tracing suspected products through the food chain.
The IDPH said it conducted the investigation jointly with the DIA, the State Hygienic Laboratory, local health departments, and public health officials from Nebraska who were investigating a similar outbreak.
Shortly after Iowa announced its findings today, the Nebraska Department of Health and Human Services (NDHHS) announced that prepackaged salad mix was the source of its Cyclospora outbreak, which has sickened 78 people in the state so far.
The NDHHS also said its investigation found that the salad mix, which contained iceberg and romaine lettuce along with carrots and red cabbage, came through national distribution channels, with no indication that locally grown produce was connected to the outbreak.
The US Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) both posted outbreak updates today saying they are aware of the Iowa and Nebraska investigation findings about the salad mix but that they are still assessing information from other states to see if the findings apply to illnesses there.
The FDA said it is following the strongest leads provided by the states and has prioritized the salad mix ingredients identified by Iowa for the trace-back investigation but that it is following other leads as well.
According to the FDA, its trace-back team identifies clusters of people sickened in the outbreak from different geographic areas and follows the foods they ate back to a common source, which is labor-intensive, painstaking work. The FDA added that it has appointed a seven-person team at its headquarters to help solve the outbreak.
Christine Mann, a spokeswoman for the Texas Department of State Health Services (TDSHS), told CIDRAP News that so far Texas investigators have not determined a common source of exposure linking the state's Cyclospora illnesses.
Florida epidemiologists also don't have conclusive evidence of a common food item that the state's Cyclospora patients consumed, Ashley Carr, a spokeswoman for the Florida Department of Health (FDH), told CIDRAP News. She added that state health officials are working with the CDC to identify the source of the infections and that interviews are under way to carefully examine the patients' food and ingredient exposures.
So far it's not clear which ingredient was contaminated or if any of the salad components came from imported sources. Cyclospora infections are rare, and past outbreaks have been linked to imported vegetables and fruits. No prepackaged salad products have been recalled as yet.
Today's CDC update said that as of yesterday the agency had received reports of 372 Cyclospora infections from 15 states and New York City. The only new location that was reported is outstate New York, which notified the CDC of a case in a patient who was likely infected in another state.
Some states that had reported cases earlier, such as Florida, Texas, Nebraska, and Wisconsin, reported additional cases, according to the CDC's update.
Florida's outbreak update yesterday included information about the epidemiologic patterns seen among the sick patients. The average age of the patients is 57.5 years, with an age range of 22 to 78. Fourteen patients have been women and 10 were men.
Meanwhile,Texas health officials today announced 11 more cases beyond the CDC's total. Additional new cases reported by Nebraska would raise the unofficial outbreak total to 385.
Jul 30 IDPH press release
Jul 30 NDHHS press release
Jul 30 CDC update
Jul 30 FDA outbreak update
Jul 29 FDH press release
Jul 29 TDSHS press release