614. Foodborne disease outbreaks associated with cheese, 1998-2008
Session: Poster Abstract Session: Outbreak Investigation
Friday, October 21, 2011
Room: Poster Hall B1
Background: Dairy products, including cheese, are a staple of the American diet.  We described the frequency and characteristics of outbreaks attributed to cheese.   

Methods: We reviewed data from the CDC Foodborne Disease Outbreak Surveillance System for outbreaks during 1998-2008 where cheese was reported as the implicated food vehicle.    

Results:Cheese was reported as the implicated food vehicle in 68 outbreaks, resulting in 1519 illnesses, 178 hospitalizations, and 3 deaths.  The pasteurization status of the milk used to make the cheese was known for 64 (94%) outbreaks; 30 (47%) involved cheese made from unpasteurized milk.  Among the unpasteurized cheese outbreaks, most (15 outbreaks, 50%) involved queso fresco or homemade cheese (7, 23%).  The cheese type was not listed for 24 of the pasteurized cheese outbreaks; the remaining were due to a variety of cheeses.  The etiologic agents reported for unpasteurized cheese outbreaks were Salmonella (12 outbreaks, 40%), Campylobacter (7, 23%), Brucella (4, 13%), Listeria (3, 10%), Shigella (2, 7%), and Shiga toxin-producing E. coli (STEC; 2, 7%).  Of the 23 pasteurized cheese outbreaks in which the etiologic agent was reported, most were due to norovirus (12, 52%), followed by Salmonella (4, 17%), Listeria (2, 9%), and Bacillus cereus, STEC, Shigella, Staphylococcus aureus enterotoxin, and another virus (1 outbreak each, 4% each).  The most common contributing factor reported in unpasteurized cheese outbreaks was raw product or ingredient contaminated by pathogens from animals or the environment; this was not reported for any of the pasteurized cheese outbreaks.  In contrast, the most common contributing factors in pasteurized cheese outbreaks were handling by an infected person or bare-handed contact by a food worker.

Conclusion: The types of cheese and etiologic agents involved in outbreaks attributed to cheese varied depending on whether the milk used to make the cheese was pasteurized. Outbreaks associated with unpasteurized cheese were more frequently due to pathogens transmitted from animals and their environments, whereas pasteurized cheese outbreaks were associated with contamination by food handlers.   Understanding the sources and routes of contamination can help to improve the safety of cheese products. 

Subject Category: N. Hospital-acquired and surgical infections, infection control, and health outcomes including general public health and health services research

L. Hannah Gould, PhD, Elisabeth Honorat, MS, MPH and Casey Barton Behravesh, DVM, Centers for Disease Control and Prevention, Atlanta, GA


L. H. Gould, None

E. Honorat, None

C. Barton Behravesh, None

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.