CDC unveils pathogens and foods linked to foodborne illness

CDC found that the pathogen-commodity pair of listeria and poultry was followed by Salmonella and fruits/nuts (14 deaths), and shiga toxin–producing E.coli (STEC) and leafy vegetables (seven).

However, outbreaks associated with Salmonella caused the most deaths (60 deaths), followed by Listeria (48), and STEC (22).

CDC reported the findings in its “Surveillance for Foodborne Disease Outbreaks in the US from 1998 to 2008​​”, which describes the number of illnesses, hospitalizations and deaths from contaminated food and water.

Outbreaks caused by viruses with a single confirmed or suspected etiology increased, replacing bacterial pathogens as the most common etiology group reported in foodborne disease outbreaks.

This increase was in large part caused by increased norovirus diagnostic capacity in state health department laboratories and improved strategies to obtain specimens for diagnostic testing.

Commodity pairs​

The pathogen-commodity pairs responsible for the most outbreaks were scombroid toxin/histamine and fish (317 outbreaks), ciguatoxin and fish (172 outbreaks, Salmonella and poultry (145 outbreaks) and norovirus and leafy vegetables (141 outbreaks).

Those responsible for the most outbreak-related illnesses were norovirus and leafy vegetables (4,011 illnesses), Clostridium perfringens and poultry (3,452), Salmonella and vine-stalk vegetables (3,216) and Clostridium perfringens and beef (2,963).

Salmonella and fruits/nuts was the top pathogen-commodity pair responsible for the most hospitalizations (452 hospitalizations), Salmonella and vine-stalk vegetables (441), STEC and beef (340), and STEC and leafy vegetables (301).

Foodborne disease outbreaks annually declined within 1998–2008 but there were no consistent national trends in outbreak reporting that contributed to this decline, said the CDC.

Pathogens confirmed​

Eight pathogens caused 89% of the 5,059 confirmed, single-etiology outbreaks, including norovirus (39%), Salmonella (26%), Shiga toxin–producing E. coli (STEC) (6%), scombroid toxin/histamine (5%), Clostridium perfringens (5%), Staphylococcus enterotoxin (3%), ciguatoxin (3%), and Campylobacter jejuni (2%).

Among the 67,752 illnesses in outbreaks, those associated with the most outbreak-related illnesses were poultry (17%), leafy vegetables (13%), beef (12%), and fruits/nuts (11%).

CDC said the average annual number of outbreaks reported during 1998–2008 was more than double the average annual number reported during 1973–1997.

A food vehicle was reported for 7,724 (58%) outbreaks and the percentage of outbreaks with an implicated food decreased from 63% in 1998 to 46% in 2008.

Norovirus was among the leading cause of outbreaks across foods and settings indicates that reliance on routine culture for enteric bacteria is inadequate during outbreak investigations.

Poultry and beef were associated most commonly with outbreaks caused by bacteria, leafy vegetables were implicated most commonly in viral outbreaks, and fish was implicated most commonly in scombroid and ciguatoxin outbreaks.

However, the agency said for many reports, information on certain aspects of the outbreak, such as the etiology or the implicated food vehicle, is missing or incomplete and only a small percentage of foodborne illnesses reported each year are identified as associated with outbreaks.