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Multistate outbreaks offer key lessons to improve food safety
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Every year in the United States, foodborne disease outbreaks hospitalize 128,000 individuals and claim the lives of 3,000, according to the CDC. Despite accounting for only 3% of reported outbreaks in the country, multistate outbreaks caused more than half of all foodborne disease deaths between 2010 and 2014.
“CDC’s disease detectives are finding an increasing number of outbreaks that occur in many states at once,” Thomas R. Frieden, MD, MPH, director of the CDC, said during a telebriefing in November. “These multistate foodborne outbreaks can be big, and they can be lethal.”
According to some experts, however, multistate outbreaks during the past year may offer valuable lessons to help improve food safety.
From 2010 to 2015, a Listeria outbreak linked to Blue Bell Creameries hospitalized 10 people and killed three across four states, according to the CDC. Although relatively small in size, the outbreak revealed that Listeria can live in ice cream, according to Ian Williams, PhD, MS, chief of the Outbreak Response and Prevention Branch at the CDC.
“It was a wake-up call to the ice cream industry,” Williams told Infectious Disease News. “It caused Blue Bell to close down their plants, completely retool, and withdraw all their product from the market. It caused a lot of people in the industry to go back and take another look at how they were producing their food.”
From July to November 2015, a Salmonella Poona outbreak linked to cucumbers imported from Mexico hospitalized 165 people and killed four across 38 states, according to the CDC. This outbreak called attention to the need for improved food inspection practices, particularly of products originating from outside the U.S., according to Herbert L. DuPont, MD, director of the Center for Infectious Diseases at the University of Texas School of Public Health and an Infectious Disease News Editorial Board member.
“Right now, you and I are eating 260 pounds of food a year that comes from another country, and the inspection of that food probably does not occur,” DuPont said in an interview. “For both foreign and domestic food, we inspect less than 10% that go into our grocery stores and restaurants.”
As of Dec. 18, an Escherichia coli outbreak linked to Chipotle Mexican Grill restaurants hospitalized 20 people across nine states, according to the CDC. In addition, the CDC is investigating another outbreak of a different strain of E. coli linked to Chipotle. While the cause of both outbreaks is unknown, some experts suspect the consumption of fresh produce, according to Timothy F. Jones, MD, state epidemiologist for the Tennessee Department of Health, and an Infectious Disease News Editorial Board member.
“A lot of outbreaks that we are starting to see are due to fresh produce and things that are not cooked, which are becoming popular in younger populations and the ‘foodie’ culture,” Jones told Infectious Disease News. “With fresh produce, you do not have that decontamination step of cooking. So, as the consumption of uncooked fruits and produce increases, the risk of them being contaminated and consumed increases.”
Better detection and regulation
While lessons from foodborne disease outbreaks in 2015 may help improve food safety in the future, two improvements already have begun to take place.
For the past 15 years, the CDC has used pulsed-field gel electrophoresis (PFGE) to detect foodborne disease. More recently, the agency has begun to use whole-genome sequencing (WGS) to identify more outbreaks, according to Jones.
“Relative to WGS, PFGE is pretty crude,” Jones said. “It is chopping up the bacterial DNA into five bands, eight bands, 10 bands. WGS looks at the entire DNA sequence. With WGS, we are going to have even better capacity to more finely separate bacteria.”
In addition, the FDA has sought to strengthen its regulation of food products. In response to the S. Poona outbreak caused by Mexican cucumbers, the FDA outlined its most recent rules to enforce the 2011 Food Safety Modernization Act. These will help to prevent contamination on farms that export to the U.S.
“There has been a lot of work with FDA and Mexico about how to ensure the safety of produce coming from there,” Williams said. “Some of it is testing the food. Some of it is improving practices on the farm.” – by Will Offit
- Reference:
- CDC. List of Selected Multistate Foodborne Outbreak Investigations. http://www.cdc.gov/foodsafety/outbreaks/multistate-outbreaks/outbreaks-list.html. Accessed December 28, 2015.
Disclosures: DuPont, Frieden, Jones and Williams report no relevant financial disclosures.