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Foodborne illnesses and outbreaks

Information for Local Health Departments

Foodborne illnesses caused by the consumption of contaminated food, drink, and other ingestibles are a leading cause of disease in the United States. The U.S. Centers for Disease Control and Prevention (CDC) has estimated that every year in the United States:

      • 48 million people get sick from a foodborne illness
      • 128,000 people are hospitalized because of a foodborne illness
      • 3,000 people die from a foodborne illness

In the United States, the top five pathogens that cause foodborne illnesses are norovirus, Salmonella, Clostridium perfringens, Campylobacter, and Staphylococcus aureus. Some other pathogens are less common, but can cause more severe illness; these include Shiga toxin-producing Escherichia coli, Listeria, Vibrio, and Clostridium botulinum.

Many foodborne illnesses cause characteristic gastrointestinal symptoms including diarrhea, vomiting, nausea, and abdominal cramps; in most cases, symptoms are self-limiting and do not require treatment. However, some foodborne illnesses can cause severe disease, resulting in hospitalization, long-term health complications, or even death. Groups at higher risk for severe foodborne illness include:

      • Pregnant women

      • Children under the age of 5 years

      • Adults aged 65 years and older

      • People with certain medical conditions or treatment regimens that weaken the immune system (such as diabetes, liver disease, HIV/AIDS, chemotherapy, and radiation)

Interviewing Patients

  • It is important to interview patients as soon as possible after they are identified for more accurate recall of food and other exposures.

  • Please use the appropriate CDPH case report forms (CalREDIE tabs or PDFs in the CalREDIE Document Repository).

Healthcare providers are required to report suspect cases of foodborne illness to the local health department (LHD) within specified timeframes. For some pathogens, clinical laboratories are required to submit clinical isolates or specimens to a local public health laboratory or the California Department of Public Health (CDPH) for definitive identification.

Foodborne Outbreaks

Nearly all of the pathogens known to cause foodborne illness can cause a foodborne outbreak. The Council of State and Territorial Epidemiologists (CSTE) defines a foodborne outbreak as an incident in which two or more persons experience a similar illness after ingestion of a common food, and epidemiologic analysis implicates the food as the source of the illness.
Foodborne outbreak tracingFoodborne outbreaks associated with food service establishments (restaurants, caterers, delis, etc.) most commonly occur when pathogens are transmitted to people either by:
  • food contaminated at a farm, production facility, or distribution facility,
  • food contaminated by an ill food worker, or
  • food contaminated via contaminated surfaces at food service establishments.

California Code of Regulations, Title 17, requires healthcare providers to immediately report cases of foodborne illness to the LHD if an outbreak is suspected.

Foodborne outbreak surveillance helps identify pathogens, foods, settings, and conditions that contribute to foodborne outbreaks. Foodborne outbreak investigations are conducted through collaboration between public health staff from epidemiology/communicable diseases, public health laboratory, and environmental health disciplines. These investigations help public health officials control outbreaks and prevent more people from getting sick. 

Foodborne Outbreak Reporting

For LHDs participating in CalREDIE:

  • Create an outbreak report in CalREDIE by creating a “GI, Foodborne” outbreak and completing the “Foodborne OB” tab.

For LHDs not participating in CalREDIE:

Guidelines for completing the CDPH Foodborne Disease Outbreak Report (PDF) are available in the CalREDIE Document Repository. CDPH Infectious Diseases Branch staff review foodborne disease outbreak reports and enter the reports into CDC’s National Outbreak Reporting System (NORS).

The CalREDIE Document Repository has the following forms and guidance documents:

  • Foodborne Disease Outbreak Report (CDPH 8567)

  • Guidelines for Completing the
    CDPH 8567

  • NORS Guidance for Contributing Factors

  • Case-Control Study Table

  • Cohort Study: Food-Specific Attack Rate Table

Multistate Foodborne Outbreaks

Multistate foodborne outbreakMany outbreaks involve cases of foodborne illness caused by contaminated food, drink, or materials that are distributed in stores or food service establishments across multiple states in the U.S. In these outbreaks, CDPH coordinates with public health professionals in local health jurisdictions, other states, and federal agencies to determine the source of the outbreak and prevent additional illnesses.

For more information about how multistate outbreaks are detected through whole genome sequencing, please visit the CDC PulseNet Frequently Asked Questions webpage.


Foodborne Outbreak Tools and Trainings​


​   Tra​​inings​

 CDC Integrated Food Safety Centers of Excellenc​​​​e (CoE) Trainings:  

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