New Estimates Lower Incidence of Food Poisoning

The Centers for Disease Control and Prevention has released a new, lower estimate of the overall public health burden of foodborne illness in the United States.  CDC now says food poisoning sickens 1 in 6 Americans each year, not 1 in 4 as the agency had estimated in 1999.

According to the new estimates announced Wednesday, about 48 million fall ill, 128,000 are hospitalized, and 3,000 die each year from foodborne diseases.  For the past decade, the most reliable estimates were 76 million annual foodborne illnesses, 325,000 hospitalizations, and 5,000 deaths.

CDC officials emphasized that the significantly lower estimates are the result of better data and smarter methodology, not a steep decline in the actual number of illnesses.  A number of critical differences in data and methodology impact the numbers–so it is not possible to make a direct comparison between the reports.

“The lower numbers are largely the result of more and in some cases better data than we had in 1999 and also innovative, new methods that we have developed to calculate the current estimates,” explained Dr. Chris Braden, director of CDC’s Division of Foodborne, Waterborne and Environmental diseases, on a call with reporters. “For this reason, we really can’t compare the two estimates to measure trends, as tempting as that may be.”

The new report is the first national estimate that focuses solely on illnesses caused by foods eaten in the United States. CDC’s earlier report, by Paul Mead et al, included illnesses acquired from food consumed abroad.

The 1999 estimate used 1996-1997 surveys from FoodNet, the 10 states that make up a food surveillance network, and data from U.S. studies conducted before 1980. The new estimate draws on FoodNet surveys ranging from 2000 to 2007.

The new estimate is also based on a stricter definition of gastroenteritis and uses a number of more accurate, and more conservative, multipliers to make estimates about unreported illnesses.

For example, in 1999, CDC found that 15 percent of survey respondents sought medical care for bloody diarrhea, while the new survey results indicate that 35 percent seek care.  These numbers greatly impact the CDC’s estimates in correcting for under-diagnosis.  Most people who come down with foodborne illness aren’t counted in CDC’s FoodNet detection system, because they didn’t see a doctor, cultures weren’t taken or testing did not confirm a pathogen.

Out of the estimated 48 million people who get sick from contaminated food each year, CDC estimates that 9.4 million of the illnesses are caused by 31 known foodborne pathogens.

CDC estimates that 90 percent of all illnesses due to known pathogens are caused by seven pathogens: Salmonella, norovirus, Campylobacter, Toxoplasma, E. Coli O157, Listeria and Clostridium perfringens.

According to the revised estimates, norovirus in the most common of the known pathogens, responsible for 5.4 million illnesses and 149 deaths each year.  Salmonella is now estimated to cause more than a million illnesses and 378 deaths annually.  E. coli toxins are estimated to cause 176,000 illnesses and 20 fatalities a year.  Campylobacter is estimated to cause 845,024 illnesses and 76 deaths.  Listeria is one of the most lethal pathogens, estimated to cause 1,591 illnesses and 255 deaths.

“The remaining 38 million illnesses are from unspecified agents, which include known agents without enough data to make specific estimates, agents not yet recognized as causing foodborne illness, and agents not yet discovered,” according to CDC.  “In both the 1999 and current estimates, unspecified agents were responsible for roughly 80 percent of estimated illnesses.”

Using the new numbers, reducing foodborne illness by one percent would keep about 500,000 Americans from getting sick each year and reducing foodborne illness by 10 percent would keep about five million from getting sick, according to CDC.

Reaction from the public health community

Consumer, public health, and industry groups alike welcomed the updated estimates.

Dr. Richard Raymond, former under secretary for food safety at the U.S. Department of Agriculture, lauded the new report.  Raymond has been a vocal critic of the way the outdated foodborne illness stats were being used to further political agendas.

“I think it’s a tremendous improvement,” Raymond said. “They really did the best they can with what they got. Any weakness, as they said, is because of lack of data.”

“I think in 10 years form now they will be even better,” he added.

Caroline Smith DeWaal, food safety director at the Center for Science in the Public Interest, said she hopes there will be more revisions as better information becomes available.  “A report like this should be coming every two years, not every 10 years. It is my hope that they can deliver this kind of information more quickly.”

DeWaal contends that if CDC kept consistent data sources and methodology, then the  estimates could be better used to track increases or decreases in particular pathogens.

“I think the more up-to-date numbers from the CDC are excellent,” said Bill Marler, food safety attorney and publisher of Food Safety News.  “There are two things that the data show clearly: first,  the need for more resources at the CDC and state health departments to track foodborne disease, and second, that the numbers are not mere statistics; they represent real people and families with horrible losses, medical expenses and wage loss, and represent businesses with recall costs and lost sales.”

The Consumer Federation of America echoed similar concerns about the ability of local and federal public health agencies to accurately capture the public health costs of foodborne illness.

“[The new report] also demonstrates that, a decade after the first effort to estimate the total burden of foodborne illness, the nation remains largely ignorant of the full human and economic costs of these preventable diseases,” the consumer group said in a statement. “The CDC acknowledges that the majority of illnesses are caused by unidentified organisms and that their data rely on estimates because local, state and national surveillance and reporting systems remain primitive.  Most people stricken by gastrointestinal illness are never seen by a physician and if they are, only a few are tested to determine the organism that caused the illness.”

CFA also said the prevalence of illnesses caused by “unspecified agents” illustrates the lack of adequate information about foodborne illness and the need for more intense surveillance and reporting.  It is difficult to prevent people from getting sick, the group noted, if you don’t know what is making them sick.

Dr. Braden said the new estimates will serve as a foundation for future reports and that CDC is working to improve foodborne illness surveillance. CDC hopes to release data on food attribution–which foods are most often linked to particular pathogens–in 2011.

Originally published on Food Safety News

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