Purpose: To describe the frequency and characteristics of outbreaks attributed to nuts and associated products.
Methods: The Centers for Disease Control and Prevention (CDC) conducts surveillance for foodborne disease outbreaks. We reviewed data for outbreaks in which nuts or a product made from nuts was reported as the food vehicle during 1998- 2009. We analyzed outbreak frequency and size, hospitalizations and deaths, pathogens, and settings of food preparation.
Results: From 1998-2009, 11 outbreaks were reported, resulting in 1,645 illnesses, 309 hospitalizations, and 10 deaths. At least one outbreak occurred in each reporting year except 1999, 2000, and 2009. Three outbreaks were associated with peanuts, three with almonds, two with peanut butter/peanut paste, two with unspecified nuts, and one with cashews. The average outbreak size was 20 illnesses; the two peanut butter outbreaks were particularly large and severe, sickening more than 700 persons each and accounting for all but one of the deaths. Of the eight outbreaks with an etiology reported, five were caused by Salmonella (serotypes Enteritidis [2 outbreaks], Tennessee, Thompson, Typhimurium), two were caused by chemicals, and one was caused by norovirus. In five outbreaks the etiologic agent was isolated from the implicated food. Six outbreaks were associated with nuts distributed as a commercially pre-packaged product (peanut butter [2 outbreaks], peanuts [2 outbreaks], almonds, cashews); three involved products distributed to and causing illness in multiple states.
Significance: Outbreaks associated with consumption of contaminated nuts or products made from nuts occurred regularly in recent years. Most involved commercially pre-packaged products. Because nuts are frequently consumed raw, these findings underscore the importance of on-farm and processing practices to ensure food safety.