Salmonella in eggs causes one of the largest foodborne outbreaks in history

By Kara Watarida, Associate Specialist, PulseNet, APHL

Looking back at 2010, one of the largest foodborne outbreaks in history occurred.  Who would have suspected that a national increase of Salmonella ser. Enteritidis infections would make history?  This outbreak was linked to shell eggs and thus far is the largest S. Enteritidis outbreak and the largest egg recall to date.  Nearly 2,000 reported cases were likely associated with this outbreak and over 500 million shell eggs recalled.  This investigation was one of the largest collaborative efforts by public health professionals across the country.

This outbreak proved to be a challenge for laboratorians, epidemiologists and investigators.  S. Enteritidis is one of the most common Salmonella serotypes reported and the outbreak strain is the most common S. Enteritidis PFGE pattern in the PulseNet database.  Because of the commonality of this S. Enteritidis PFGE pattern, relying strictly on PFGE subtyping was not sufficient to determine which cases might have been outbreak-associated.  Also, eggs are a common food item, whether eaten or used as an ingredient.  All these factors complicated the investigation but through the collaborative work between laboratorians, epidemiologists and environmental health specialists, eggs from a common supplier were found to be the likely source of this outbreak. 

The coming years will show if the recent FDA Egg Rule, implemented in July 2010, will decrease the incidence of egg-associated S. Enteritidis infections.  APHL will continue to work collaboratively with public health and agriculture laboratories, CDC, FDA and USDA, as well as with food safety partners to ensure the safety of our food supply and the health of our nation.

For more information on S. Enteritidis infections and prevention, please visit the CDC website.