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Foodborne Illness and Outbreak Investigations

A Farm to Table Overview

California Field Worker

In the United States, an estimated 48 million foodborne illnesses occur each year. A foodborne illness is caused by eating or drinking a contaminated food or beverage.

When two or more people get the same illness from the same contaminated food or drink, the event is called a foodborne outbreak. Illnesses that are not part of outbreaks are called "sporadic."

More than 250 pathogens and toxins are known to cause foodborne illness. Nearly all of them can cause an outbreak.

Here, we explain the importance of tracking foodborne illness and provide a farm to table snapshot of how the public health community detects, investigates, and controls foodborne outbreaks.

Chart: Top pathogens contributing to domestically acquired foodborne illnesses and deaths, 2000 to 2008. Norovirus: Illnesses 58%; Deaths 11%. Salmonella, nontyphoidal: Illnesses: 11%; Deaths 28%. Clostridium perfringens: Illnesses: 10%. Campylobacter spp.: Illnesses: 9%; Deaths 6%. Staphylococcus aureus: Illnesses: 3%. Toxoplasma gondii: Deaths: 24%. Listeria monocytogenes: Deaths: 19%..Foodborne Illness

Foodborne illnesses are caused by pathogens and toxins (chemicals). Pathogens are germs, such as bacteria, viruses, and parasites, that can cause illness. More than 250 pathogens and toxins are known to cause foodborne illness. Nearly all of them can cause an outbreak.

Chart: Contributions of different food categories to estimated domestically illnesses and deaths, 1998-2008*.  Produce   Illnesses - 46%  Deaths - 23% ; Meat and Poultry Illnesses - 22% Deaths - 29%;Dairy and Eggs Illnesses - 20% Deaths - 15%; Fish and Shelfish Illnesses - 6.1% Deaths - 6.4%Food and Outbreaks

Many types of foods can become contaminated. Some of the foods that have been linked to outbreaks are eggs, fish and shellfish, meat, nuts, poultry, raw (unpasteurized) milk, and raw fruits and vegetables.

Food Safety and Raw MilkThe Food Production Chain

It takes several steps to get food from the farm or fishery to the dining table. We call these steps the food production chain. Contamination can occur at any point along the chain—during production, processing, distribution, or preparation.

sproutsSize and Extent of Foodborne Outbreaks

The size and scope of a foodborne outbreak can vary based on which pathogen or toxin is involved, how much food is contaminated, where in the food production chain contamination occurs, where the food is served, and how many people eat it.

sproutsKey Players in Foodborne Outbreak Response

Which agency or agencies participate in an investigation depends on the size and scope of the outbreak.  Most reported foodborne disease outbreaks involve only one state and are investigated by local or state public health agencies.  

man working at his computerMultistate and Nationwide Foodborne Outbreak Investigations

In recent years, large multistate or nationwide foodborne outbreaks have become more commonly recognized.

Reduce the risk of Salmonella from EggsPreventing Future Outbreaks

The ultimate goal for public health and food safety officials is not just stopping outbreaks once they occur, but preventing them from happening in the first place.

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