NORS Basics

NORS is a web-based platform that local, state, and territorial health departments in the United States use to enter outbreak information.

Through NORS, CDC collects reports of enteric illness outbreaks caused by bacterial, viral, parasitic, chemical, toxin, and indeterminate/unknown agents. NORS also contains reports of foodborne and waterborne outbreaks of diseases that are not enteric.

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In NORS, an outbreak is defined as two or more cases of similar illness associated with a common exposure.

An enteric illness is an intestinal illness with symptoms such as diarrhea, nausea, or vomiting.

Some germs, such as Escherichia coli, cause enteric illness and may cause other types of symptoms or conditions that are not enteric. Those include hemolytic uremic syndrome, which causes anemia, low platelet count, and kidney failure.

Local, state, or territorial public health agencies usually lead an outbreak investigation. Those health agencies use NORS to report outbreaks to CDC. The system collects information such as when and where the outbreak occurred, how many people were ill, their symptoms, and what caused the outbreak. CDC checks these data for accuracy and analyzes them to identify national trends and to gather information that could prevent future outbreaks.

The general flow of outbreak information to NORS: 1) People are exposed to a pathogen; 2) People get sick and seek treatment 3) Health department is notified of a possible outbreak; 4) Health department conducts an outbreak investigation; 5) Health department enters outbreak information into NORS; 6) CDC checks data for accuracy and analyzes; 7) Data are summarized and published.

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NORS collects data on the following types of disease outbreaks in the United States:

  • Foodborne — enteric and non-enteric illness spread through food or drinks that are not water.
  • Waterborne — enteric and non-enteric illness spread through water, including water that people drink, swim in, or use for other purposes.
  • Animal contact — enteric illness spread to humans from contact with animals, such as a chicken or pet turtle, or their environments.
  • Person-to-person — enteric illness spread from one person to another through direct contact, such as by handshake.
  • Environmental contamination — enteric illness spread through contact with other environmental sources, such as dirty linens or surfaces that people touch in bathrooms.
  • Indeterminate/Unknown — enteric illness in which the mode of transmission could not be determined.

If you would like to report an outbreak, please contact your state or local health departmentexternal icon.

Page last reviewed: November 4, 2019