A few weeks ago I was looking at the 2009 FoodNet data and started thinking about the upcoming release of new numbers on the burden of foodborne illness in the United States. As you might recall in 1999 Mead and colleagues published estimates of the annual burden of foodborne illness in the U.S. These estimates – 76 million ill, 325,000 hospitalizations, and 5,000 deaths – have been cited by government, academics, citizen groups, and even industry as a call for action to improve food safety nationally and internationally. Ten years ago, who anticipated the deluge of “Monday night quarterbacks” today eager to criticize a sincere attempt to characterize a serious public health and individualal health problem in our country? Yes, it is time for revised estimates and I, along with others, eagerly anticipate release of the new estimates rumored to occur sometime this next week.
Undoubtedly, the revised estimates will more accurately reflect truer incidence of foodborne illness. Credit must be given to public health that has strengthened detection, surveillance, and investigation of illnesses and outbreaks at the local, state and federal level. I can only imagine the obstacles that were overcome for implementation of electronic laboratory reporting or establishing NORS, the national outbreak reporting system. Data from both are likely to be used to calculate the forthcoming estimates.
Mead et al. were clear as to the limitations of the data sources used in their seminal 1999 article. The authors described several assumptions that were made such as uncertainty in the degree of under-reporting and the frequency of acute gastroenteritis in the general population. For example, in 1999 few public health laboratories could test for norovirus in food or stool. Mead et al. attributed 30% (23 million) of the estimated 76 million illnesses to norovirus. Thanks to better laboratory detection and understanding of how norovirus spreads, the percentage of norovirus illnesses attributable to food in is likely to drop considerably in the new estimates. A better norovirus estimate ten years after 1999 does not imply that Mead et al. were careless in their methods. Rather, it highlights advancements in basic sciences and public health.
Recently, there has been no shortage of critics willing to dispute the 5,000 deaths Mead et al. attributed to foodborne illness. In June 2010 the Foodborne Disease Active Surveillance Network (FoodNet) published preliminary surveillance data for 2009 showing 74 deaths caused by the 10 foodborne pathogen it tracks. FoodNet sites represent about 15 percent of the US population which extrapolates to about 500 US deaths caused by foodborne pathogens in 2009, considerably lower than the 5,000 deaths estimated in the Mead article. However, the 500 estimated deaths would not include patients who died from a foodborne illness but who were not laboratory confirmed with a pathogen. Furthermore, I know from personal experience that patients die from injuries caused by foodborne illness after public health involvement has ceased. These patients are not counted as food related deaths. Using death certificate data to identify foodborne illness related deaths is problematic. For example, the certificate might list renal failure as the cause of death with no mention of the shigatoxin E. coli infection the decedent had two months prior. This patient also would not be counted in food death data.
The effort to estimate the “true” number of illnesses, hospitalizations, and death associated with foodborne illness requires use of many data sources and statistical adjustments to account for under-reporting and other unknown elements. We need the best data we can get to use to make decisions on how and where to fight foodborne illnesses.
The new estimates will certainly be scrutinized and used to promote different agendas. Remember, the data is only as good as the surveillance. We need to continue to support local, state and federal public health. They need the resources to keep us all healthier. I also encourage everyone to pause and remember that the estimates represent a compilation of individuals – hundreds and thousands of people I have met personally – my clients. Thankfully, most individuals will experience mild symptoms and think of their illness as a minor inconvenience. For an unfortunate few, foodborne illness will mean physical and mental anguish, financial expenditures, long-term consequences, or death.
Real people; real consequences….