CDC acts to expedite foodborne data sharing

Jul 7, 2009 (CIDRAP News) – At the same time that the Obama Administration inaugurates new safety and enforcement standards for the agencies overseeing food production in the United States, one of those agencies—the Centers for Disease Control and Prevention (CDC)—is taking steps to improve the flow of data revealing food-safety problems.

Last month, the CDC released one of its periodic reports disclosing statistics on foodborne disease outbreaks in the United States. But in a break from agency tradition, the report did not summarize and compare 2 or more years' worth of numbers.

Instead, it presented just 1 year's worth, for 2006, in an unusually granular breakdown of outbreaks by disease-causing organism—the first step in a program to push outbreak analysis out more quickly, said CDC scientist Ian Williams, PhD.

"Our hope is to get data out there for people to actually use it," said Williams, chief of the OutbreakNet team in the CDC's Division of Foodborne, Bacterial and Mycotic Diseases. "In reporting systems, there is always a lag time because data has to be aggregated, cleaned, and verified—but for any year we hope to have something out by the following fall."

Data for 2007 and then 2008 will be published soon, Williams said.

The report, titled "Surveillance for Foodborne Disease Outbreaks—United States, 2006," and published in the CDC's bulletin Morbidity and Mortality Weekly Report (MMWR), points up vulnerabilities in the food-safety system that may be more visible because they are not contrasted with other years' data. Among them: by etiology, a high percentage of outbreaks caused by norovirus (54%) followed by Salmonella (18%); and by food, a high percentage traced to leafy vegetables and fruits and nuts (17% for leafy vegetables and 16% for fruits and nuts, or 33% all told).

Such single-point reporting may be a weakness of the new system, because it cannot establish trends in the way that multi-year analyses do, said prominent food-safety attorney Bill Marler of Seattle. "It you looked just at 2006, you would think that produce is a terrible risk, but in 2007 and 2008 there were fewer outbreaks in produce and many more in meat," he said.

Marler and other food-safety advocates, though, applauded the move to get data out to the field more quickly.

"We have been asking for years to get this kind of data out more succinctly and earlier," said Donna Rosenbaum, executive director of the nonprofit organization Safe Tables Our Priority (STOP). "To put out a single-year data set is a move in the right direction."

The greatest hole in the safety net exposed by the report, though, is the large number of outbreaks for which there are no data. In 2006, 48 states reported 1,270 outbreaks (defined as two or more cases of similar illnesses linked to a common food).

But among those 1,270 outbreaks, officials could confirm a causative agent for only 621 (49%), and a causative food in only 528 (42%). In an additional 263 outbreaks (21%), an organism or chemical was suspected, but not confirmed.

The new analysis confirming those percentages "will help us get a sense of where there are holes in the system and where we need to put more effort," Williams said.

In addition to two states that reported no foodborne outbreaks at all, 12 reported none due to viral illnesses, despite the sharp rise in norovirus cases in other areas—findings that the CDC acknowledged are due to the differences in funding, lab resources, and other public-health infrastructure from state to state. (In 2006, for instance, a number of state laboratories began receiving materials that allowed them to perform diagnostic tests for the presence of norovirus.)

The data show other holes as well: chief among them, the vast number of foodborne illnesses that are presumed to happen in the United States each year but are never reported in a manner that allows them to be analyzed. Up to 76 million Americans are believed to suffer foodborne illness each year, according to previous CDC estimates; the 2006 data, though, cover only 27,634 cases among the 1,270 outbreaks that year.

"It is very concerning to us how few cases are identified and analyzed," Rosenbaum said. "Some people do suffer transient illness and get well quickly, but others suffer long-term consequences and tremendous economic loss, and have no one to hold accountable.

"Even when people do seek care and attempt to get a (lab) culture confirmation for their illness, unless there is a second, third or fourth case in the community, it is very unlikely there is going to be an investigation."

Slow progress in reducing foodborne illness was a theme in the administration announcements Tuesday, covering sweeping changes to egg safety rules. And it has been touched on in earlier CDC reports, such as an April 10 MMWR disclosing that "fundamental problems with bacterial and parasitic contamination are not being resolved."

That paper, from a sister CDC project to OutbreakNet known as FoodNet, found that for certain disease organisms, improvements in foodborne illness plateaued in 2004, and predicted that the United States would not hit 2010 goals for reducing those illnesses.

Some smaller outbreaks are never analyzed by public health, and some illnesses that look like individual cases may be part of larger or multi-state outbreaks that are not recognized, the CDC's June report said.

CDC. Surveillance for foodborne disease outbreaks—United States, 2006. MMWR. 2009 Jun 12;58(22):609-15 [Full text]

CDC. Preliminary FoodNet data on the incidence of infection with pathogens transmitted commonly through food—10 states, 2008. MMWR 2009 Apr 10;58(13):333-7 [Full text]

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