Three U.S. federal agencies said this week that they have developed an improved method for analyzing outbreak data to help determine which foods are most commonly responsible for illnesses related to four major foodborne bacteria.

The Centers for Disease Control and Prevention (CDC), the U.S. Food and Drug Administration (FDA) and the U.S. Department of Agriculture's Food Safety and Inspection Service (FSIS), working together as part of the Interagency Food Safety Analytics Collaboration (IFSAC), developed a model using new food categories that align with the regulatory framework and emphasizing more recent outbreak data.

Using this model they analyzed data from nearly 1,000 outbreaks that occurred from 1998 to 2012 to assess which categories of foods were most responsible for making people sick with Salmonella, E. coli O157, Listeria and Campylobacter.

These pathogens are considered high priority. They were chosen because of the frequency or severity of the illnesses they cause, and because targeted interventions can have a significant impact in reducing them, CDC said.

IFSAC experts found that more than 80 percent of E. coli O157 illnesses were attributed to beef or vegetable row crops, such as leafy vegetables.

Salmonella illnesses were attributed to a range of food types, with 77 percent of illnesses related to seeded vegetables (such as tomatoes), eggs, fruits, chicken, beef, sprouts or pork.

Almost three quarters of Campylobacter illnesses were attributed to dairy (66 percent) or chicken (8 percent). The analysis showed that most dairy outbreaks were related to raw milk or cheese produced from raw milk.

Limited data was available for Listeria, but more than 80 percent of Listeria illnesses were attributed to fruit (50 percent) or dairy (31 percent). The estimate for fruit reflected the impact of a single large outbreak linked to cantaloupes in 2011.

IFSAC recommended caution in interpreting certain findings, such as the estimates for Campylobacter in dairy and Listeria in fruits, but said that the results could be used with other scientific data for risk-based decision making to help prevent foodborne illness.

The new estimates, combined with other data, may also shape agency priorities and support the development of regulations and performance standards.