Collaboration encouraged to speed up outbreak investigations

It analyzed data from Center for Disease Control and Prevention’s (CDC's) Foodborne Disease Outbreak Surveillance System to describe multistate foodborne outbreaks in the US during 2010–2014.

Rapid identification of food that caused the outbreak, discovering where contamination occurred along a complex supply chain, and recalling an item distributed across the country and perhaps around the world are challenging tasks, it said.

Mexico was the leading source of imported food linked to multistate outbreaks (six), followed by Turkey (three).

Learning lessons​

Lessons learned can inform industry and government efforts to improve food safety practices.

The report gave the example of during 2013–2014 investigators linked an outbreak of 634 Salmonella serotype Heidelberg infections to handling or consuming chicken from Foster Farms.

“Public health agencies worked with the involved industry to identify the ultimate sources of the outbreak and to implement control measures. The affected company has since established new hygiene requirements at its farms and processing plants and in its product transportation practices. ​

“In January 2015, in part in response to this outbreak, USDA-FSIS proposed new production facility performance standards intended to reduce Salmonella and Campylobacter contamination of chicken and turkey parts. These standards are part of the larger body of USDA-FSIS guidance aimed at improving food safety in the meat, poultry, and egg industries.” ​

Tom Frieden, CDC director, said: “Top-notch epidemiology and new gene sequencing tools are helping us quickly track down the source of foodborne outbreaks – and together with our national partners we are working with the food industry to prevent them from happening in the first place.”​

Multistate outbreak impact​

Multistate foodborne disease outbreaks account for a disproportionate number of associated illnesses, hospitalizations, and deaths, according to the study.

During the five year period of the study 120 multistate foodborne disease outbreaks (with identified pathogen and food or common setting) were reported to CDC.

These accounted for 3% of all reported outbreaks, but were responsible for 11% of illnesses, 34% of hospitalizations, and 56% of deaths associated with foodborne outbreaks.

All states, the District of Columbia, and Puerto Rico were affected by one or more multistate foodborne disease outbreaks.

Salmonella (63 outbreaks), Shiga toxin-producing E. coli (34), and Listeria monocytogenes (12) were the leading pathogens.

Fruits (17), vegetable row crops (15), beef (13), sprouts (10), and seeded vegetables (nine) were the most commonly implicated foods.

Traceback investigations to identify the food origin were conducted for 87 outbreaks, of which 55 led to a product recall. Imported foods were linked to 18 multistate outbreaks.

Pathogen by pathogen​

Salmonella accounted for the majority of illnesses (6,530 of 7,929) and hospitalizations (952 of 1,460) and was responsible for the three largest outbreaks, which were linked to eggs (an estimated 1,939 illnesses), chicken (634), and a raw scraped ground tuna product (425).

The three most common serotypes were Newport (10 outbreaks), Enteritidis (six), and Javiana (five).

Among the 34 STEC outbreaks, almost half (41%) were linked to vegetable row crops (e.g., leafy greens) and another quarter (24%) to beef.

Twenty (59%) of the multistate STEC outbreaks were caused by serogroup O157. Serogroups O26 and O145 were responsible for three each.

Listeria monocytogenes caused 12 multistate outbreaks. Six resulted from contaminated dairy products, three from fruit, and one from sprouts. 

It was the most deadly pathogen accounting for 57 deaths, 86% of the total. Thirty-three (58%) occurred in a single outbreak linked to cantaloupe. 

“The continued partnership of FDA, CDC, USDA and our partners at the state and local levels is essential to responding to foodborne outbreaks. But consumers should be able to have confidence that steps are being taken from farm to table to minimize the risk of illness from the food they feed their families,”​ said Michael Taylor, FDA deputy commissioner for Foods and Veterinary Medicine.