July 1, 2013

 

Poultry, fish, beef remain world's leading sources of food-related illnesses

 

 

Poultry, fish and beef were consistently responsible for the greatest proportion of foodborne illness outbreaks globally between 1998 and 2008.

 

Experts at the Centres for Disease Control (CDC) and Prevention reviewed the 13,405 food-related outbreaks reported during this time period, identifying 3,264 outbreaks that could be attributed to a specific food category. Fish and poultry remained responsible for the greatest share of these outbreaks over these 20 years - accounting for about 17% of outbreaks each - followed closely by beef, which was responsible for 14% of outbreaks.

 

Eggs, on the other hand, played an increasingly smaller role as outbreak sources - accounting for 6% of outbreaks in 1998-99 and for just 2% in 2006-08. This trend was largely due to a decrease in the amount of salmonella outbreaks linked to eggs, according to the reports.

 

Leafy greens became a more common outbreak source, responsible for 6% of outbreaks in 1998-99 and 11% by 2008-09. Dairy also grew as an outbreak source, rising from 4% in the beginning of the period studied to 6% by 2006-08.

 

The researchers also looked at the leading pathogen-food combinations that caused outbreaks during the 20-year window, finding that histamine in fish was the most common outbreak source, followed by ciguatoxin in fish, salmonella in poultry and norovirus in leafy vegetables.

 

"You see the same combinations of pathogens and foods repeatedly," said Hannah Gould, epidemiologist in the Division of Foodborne, Waterborne, and Environmental Diseases at CDC's National Centre for Emerging and Zoonotic Infectious Diseases and lead author of the report. The authors note that the number of outbreaks linked to these commodities should not be confused with the number of illnesses caused by these foods, as outbreaks result in varying numbers of illnesses.

 

While poultry was responsible for the largest share of illnesses (17%) between 1998 and 2008, leafy greens were the next greatest cause of illness, accounting for 13% of the 67,752 illnesses attributed to an outbreak food source. The pathogen/commodity pairs responsible for the most outbreak-related illnesses were norovirus and leafy vegetables, which led to 4,011 illnesses of the 67,752 linked to a designated commodity category.

 

The team also looked at food preparation, finding that restaurants and delis accounted for the vast majority (68%) of the places where outbreak-linked foods were prepared. Private homes were the next most common place of preparation, at 9%, followed by catering or banquet facilities (7%).

 

"Leafy greens and norovirus continue to be a problem and norovirus has been the number one cause of outbreaks in our data for so many years and has remained that way," said Gould. She also led an analysis of foodborne illness outbreaks that occurred between 2009 and 2010 - published in January of this year - which found that during that period, beef, dairy, fish, and poultry were associated with the largest number of foodborne disease outbreaks.

 

That report also showed that unpasteurised dairy products are the leading cause of dairy-related outbreaks, accounting for 81% of the outbreaks linked to dairy during that time period. Gould said the 1998-2008 report shows that the incidence of raw dairy-related outbreaks has been growing over this time.

 

The data used for this report comes from CDC's Foodborne Disease Outbreak Surveillance System, which was started by CDC in 1973 and went online in 1998. The authors chose 1998-2008 as their reporting period because the format of the database changed starting in 2008, when it became the National Outbreak Reporting System.

 

Although this new report may appear similar to one CDC released in January titled "Attribution of Foodborne Illnesses, Hospitalisations, and Deaths to Food Commodities by Using Outbreak Data, United States, 1998-2008," the two are very different. The January report offers an estimation of total US illnesses linked to various food sources. Though it is based on data from the Foodborne Disease Outbreak Surveillance System, the figures in that report are extrapolated based on national foodborne illness estimates, while this June report looked only at outbreaks reported to CDC.