8 Things to Know about Bacterial Outbreaks from the Recent CDC Report on Foodborne Outbreaks and Illness

I’ve spent some time analyzing the recent data released by the CDC on foodborne disease outbreaks and illnesses for the period 1998-2010. My basic conclusion from a review of the numbers is that our food supply seems to be safer than the broad estimates provided by the CDC and, as a result, reported by the news media and assumed by the general public.

I discuss some of the broad numbers in my latest blog for Food Safety Magazine, but drill down specifically into foodborne bacterial outbreaks in this blog.

You find the two CDC reports referenced in this blog and the Food Safety Magazine blog at the links below:

Let’s start with the broad numbers from the CDC reports. Then, given Strategic Consulting’s specific interest in microbiology diagnostics, we’ll look more closely at CDC’s confirmed outbreak information with bacteria as the causative agent.

1. Total Confirmed Outbreaks

a. 1998-2008—4,589
b. 2009-2010—1,527
c. Total—6,116
d. Average outbreaks per year (all agents)—470
e. Average illnesses per year (all agents)—11,520
f. Average illnesses per outbreak (all agents)—24.5

2. Outbreaks by Agent

SCI Analysis of CDC Food Outbreaks by Agent

I find this data quite interesting. We are all aware of bacterial contamination as a major cause of foodborne disease outbreaks, and the CDC numbers bear that out: Bacteria caused 52% of all outbreaks during the 13-year period from 1998-2010.

I was surprised, however, by the low impact of chemical contamination on outbreaks. I also was surprised by the high number of outbreaks caused by viruses (Norovirus, almost exclusively). Interestingly, SCI research shows that the food industry doesn’t test for viruses.

3. Illnesses by Agent

Reported illnesses by agent mainly follows the same breakdown as food outbreaks. However, an even higher percentage of illnesses are attributed to bacteria as the cause of illness.

Analysis of CDC Report on Foodborne Illnesses by Agent - 1998-2010







4. Bacterial Outbreaks by Year

Analysis of CDC Foodborne Bacterial Outbreaks by YearI find this information to be very important. There has been a general trend downward in bacterial outbreaks since the late ‘90s. This downward trend continued until 2008, followed by a 2-year uptick in 2009 and 2010. On average, bacteria account for 227 food outbreaks per year.




5. Bacterial Illnesses by Year

Illnesses per year from bacteria are more consistent than the frequency of bacterial outbreaks. On average there are 6,616 illnesses per year caused by food outbreaks triggered by bacteria.

Analysis of CDC Foodborne Bacterial Illness by Year








6. Average Illness per Bacterial Outbreak

Analysis of CDC Average Illnesses per Bacterial Outbreak
The average illnesses per foodborne bacterial outbreak (~29 illnesses per outbreak) has remained consistent over the 13-year period, with 2006 the highest year at 45 illnesses per outbreak, and 2005 the lowest at just under 25.

7. Food Outbreaks by Organism (1998-2008)

Salmonella is clearly the leading cause of bacterial food outbreaks. Interestingly, SCI research shows that current food safety testing practices do not match perfectly with food outbreaks.

Analysis of CDC Foodborne Outbreaks by Organism

  • Salmonella is the pathogen most tested and is also the leading cause of food outbreaks.
  • Listeria is heavily tested but there are only a limited number of food outbreaks attributed to it.
  • Campylobacter is the #5 organism in terms of food outbreaks but is hardly tested by the food industry.
Much more information on food safety testing volume is contained in recent market research reports from Strategic Consulting.

8. Food Illnesses by Organism (1998-2008)

Illnesses by organism generally follow the same pattern as for food outbreaks. Salmonella is clearly the leading cause of foodborne illness in the US.

Analysis of CDC Foodborne Illnesses by Organism 1998-2010


While the food industry has more work to do, and any food disease outbreak is tragic and undesirable, food safety is better than generally portrayed by the media. And it seems that the CDC has been overestimating the problem.


This entry was posted in Blog, Food Safety, In the News and tagged , , , , , , , , , , . Bookmark the permalink.