The CDC issued a report that attributes foodborne illness cases to different foods. Calculations, based on known cases over the period from1998 to 2008, are used to estimate the number of cases caused by each disease causing agent as well as to attribute to one of 17 food types.
There are some big assumptions that are made in the report that I feel limits what headlines will report. 1) It applies known outbreaks to apply to sporadic cases. Because of this, it underestimates the number of cases caused by organisms that have illnesses which tend to be more sporadic in nature, such as Campylobacter. 2) Along those same lines, mass distributed product where a single contamination event results in a large number of illnesses, such as in bagged produce, outweighs foods that may are considered high risk for contamination. 3) In the cases where mixed food caused an illness, the blame is put on the item commodity that they determined to have caused the biggest
proportion of illnesses, rather than the real risk. 4) Some organisms don't even show up, such as Taxoplasma spp.. even though that organism is claimed to be one of the major pathogens associated with meat....(although owning multiple cats is probably a bigger risk).
The headlines from some of the major news outlets give the impression that certain foods are risky.
Philly.com - U.S. Officials Pinpoint Common Sources of Foodborne Illnesses
Reuters - U.S. government report outlines foods most prone to pathogens
Time - Here’s What Foods Are Most Likely To Have E. Coli or Salmonella
It is hard to get a real sense of real risk there is no calculation associated with the units consumed. Without this, many will jump on items that show to have a caused a higher percentage of the number of illnesses caused, but not the real risk.
My takeaways:
- Produce - Because of the way that produce is processed and distributed, a contamination event involving produce will impact many and thus gets seen as having a big impact in this report. However, if we look at the number of units sold, produce is a much smaller risk than it appears to be in this report when compared to other commodities. Not to say that there is not work that needs to be done, especially in preventing contamination events that can impact thousands of units. However, people should not be discouraged from produce due to the potential for foodborne illness.
- Dairy - raw milk should be considered the highest risk dairy product, and on the further processed side, cheese accounts for many of the cases of Listeria recently seen.
- Mollusks - raw shellfish is a high risk item, especially when you consider the small number of people that eat raw shellfish (compared to produce)
- Poultry - because it has a natural association with Salmonella and Campylobacter, there have been outbreaks. Looking at USDA monitoring records, while the levels of Salmonella in whole chicken are low, for ground poultry and parts, it is higher. So while the industry is working to lessen the prevalence of these pathogens in poultry products, elimination is unlikely.
- Meat - ground meat is the primary source of STEC E.coli. USDA testing indicates that about 0.5% of ground meat tested was positive.
- As for pathogens, Salmonella is a pathogen that seems to find its way to the consumer via a number of different food products. As for Campylobacter, it has a high prevalence on chicken, but we don't necessary see the cases; probably, because most cases are sporadic. In recent outbreaks, raw milk has been the culprit.
Has the number of foodborne illness cases dropped recently? While that seems to be the case, it is hard to tell in this report. And if policy decisions are going to be made on this report, even using weighting the data from the last five years, there may be some issues. For example, our ability to determine the agent (detection of Campylobacter as an example) has improved dramatically in the last few yeas. Additionally, issues that occurred 2 to 5 years ago may not be as big as an issue today Granted it is difficult to trend when working with minimal data. However, considerations must be taken if these calculations are used to set policy.
CDC - Emerging Infectious Diseases
Volume 19, Number 3—March 2013
Research
Attribution of Foodborne Illnesses, Hospitalizations, and Deaths to Food Commodities by using Outbreak Data, United States, 1998–2008
Author affiliations: Author affiliation: Centers for Disease Control and Prevention, Atlanta, GA, USA
Abstract
Each year, >9 million foodborne illnesses are estimated to be caused by major pathogens acquired in the United States. Preventing these illnesses is challenging because resources are limited and linking individual illnesses to a particular food is rarely possible except during an outbreak. We developed a method of attributing illnesses to food commodities that uses data from outbreaks associated with both simple and complex foods. Using data from outbreak-associated illnesses for 1998–2008, we estimated annual US foodborne illnesses, hospitalizations, and deaths attributable to each of 17 food commodities. We attributed 46% of illnesses to produce and found that more deaths were attributed to poultry than to any other commodity. To the extent that these estimates reflect the commodities causing all foodborne illness, they indicate that efforts are particularly needed to prevent contamination of produce and poultry. Methods to incorporate data from other sources are needed to improve attribution estimates for some commodities and agents.