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Questions and Answers, Surveillance for Foodborne Disease Outbreaks, 2009-10

Questions About Newest Report

1. What is the MMWR article “Surveillance for Foodborne Disease Outbreaks—United States, 2009-10” about?

Foodborne illnesses are an important public health problem in the United States.   This MMWR article, entitled “Surveillance for Foodborne Disease Outbreaks – United States, 2009-10,” is an annual summary of outbreak data collected through the Centers for Disease Control and Prevention’s (CDC) Foodborne Disease Outbreak Surveillance System (FDOSS). A foodborne disease outbreak is defined as the occurrence of two or more cases of a similar illness resulting from eating the same food.  State, local, and territorial public health departments investigate foodborne outbreaks caused by enteric bacteria, viruses, parasites, toxins and chemical agents (hereafter referred to as ‘pathogens’) and report their findings to CDC. This article presents data from reported foodborne disease outbreaks occurring in 2009-10; the information contributes to our understanding of the human health impact of foodborne disease outbreaks and the pathogens, foods, settings, and contributing factors involved in these outbreaks. 

2. What are the main take-home points from the 2009-10 Surveillance for Foodborne Disease Outbreaks MMWR?

During 2009-10, a total of 1,527 foodborne disease outbreaks were reported, resulting in 29,444 illnesses, 1,184 hospitalizations, and 23 deaths. In outbreaks with a confirmed pathogen, norovirus and Salmonella were responsible for the largest number of outbreaks and outbreak-associated illnesses, similar to other years. In outbreaks linked to foods in which all the ingredients belong to a single commodity, beef, dairy (nearly all unpasteurized), fish, and poultry were the food commodities responsible for the largest number of outbreaks, while eggs, beef, and poultry were responsible for the largest number of outbreak-associated illnesses.  Among outbreaks in which both a pathogen and single-commodity food vehicle were identified, Campylobacter in unpasteurized dairy products, Salmonella in eggs, and E. coli O157 in beef caused the most outbreaks. The pathogen-commodity pairs responsible for the most outbreak-related illnesses were Salmonella in eggs, Salmonella in sprouts, and Salmonella in vine-stalk vegetables such as tomatoes and peppers. Most foodborne illnesses are preventable, and timely investigation and reporting of foodborne outbreaks can provide information that may help to reduce foodborne illnesses.

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Questions About Outbreak Investigations and Preventing Foodborne Illness

1. What factors influence outbreak investigation and reporting by public health agencies?

Outbreak detection, investigation, and reporting are influenced by many factors such as available resources (time, staff, and laboratory capacity), health department priorities, and outbreak characteristics (size, severity).CDC typically becomes involved in outbreak investigations only when an outbreak affects multiple states or when a state, local, or territorial public health agency asks for CDC assistance with a particularly large, severe, or unusual outbreak.

2. How can this information be used to prevent foodborne illnesses?

Only a small proportion of foodborne illnesses occur as part of recognized and reported outbreaks. When illnesses occur outside an outbreak setting, it is usually impossible to know what food or other exposure caused them. Therefore, foodborne disease outbreak data provide some of the most detailed and accurate data about the sources of foodborne illnesses. Examining outbreak data can offer insights into the pathogens and foods causing foodborne illnesses, and into the factors that contribute to their occurrence. Public health officials use this information for foodborne illness prevention, education, and public policy.

3. Why is the food vehicle unknown for so many reported outbreaks?

CDC encourages states to report all foodborne disease outbreak investigations, even if the food vehicle is not determined. Even well-conducted investigations sometimes do not identify a food vehicle. There are many reasons for this – one is that sometimes most ill persons ate many of the same food items, so a single food can't be pinpointed. Although determination of the contaminated food vehicle is ideal, much can still be learned from outbreaks that are known to be transmitted by food but for which the vehicle is not determined.  For example, information about the pathogen, the setting (e.g., restaurant, home, school), the number ill, and whether someone died, is usually available, and this data is useful in designing prevention measures.

4. Can the type of data in this analysis be used to estimate the total number of US illnesses due to various food commodities?

Few people know what causes their illnesses, and even when they guess, it is difficult to pinpoint the source accurately. Outbreak investigations provide direct links between foodborne illnesses and the foods causing them. Therefore, data from foodborne disease outbreak surveillance are an important source for making estimates of the total number of US illnesses due to various food commodities.

Next week, the Emerging Infectious Diseases journal will publish a study that used data from the Foodborne Disease Outbreak Surveillance System to estimate the number of illnesses acquired in the United States that can be attributed to each food commodity.

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More Information

Where can I go for more information on foodborne outbreaks?

  • To view the article, ‘Surveillance For Foodborne Disease Outbreaks—United States, 2009-10’ in its entirety along with supplemental tables, visit the Foodborne Disease Outbreak Surveillance web page.
  • For data on individual outbreaks including etiology, locations, and food vehicles, visit our Foodborne Outbreak Online Database (FOOD) website.
  • For information on foodborne disease outbreak investigations, including multistate outbreaks and surveillance data from previous years visit the Outbreak Response website.
  • For information on foodborne disease prevention and current product recalls and alerts, visit the CDC's Food Safety and the Food websites.
  • For information on the new Food Safety Modernization Act and CDC’s role, visit the CDC and the Food Safety Modernization Act web page.
  • For resources on reporting foodborne disease outbreaks for state and local health departments, visit the National Outbreak Reporting System (NORS) website.

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