Skip directly to search Skip directly to A to Z list Skip directly to navigation Skip directly to site content Skip directly to page options
CDC Home

Reporting and Surveillance for Norovirus


Currently, state, local, and territorial health departments are not required to report individual cases of norovirus illness to a national surveillance system. They may not know about such cases because most hospitals and doctor’s offices do not have capability to test for norovirus. The virus is usually diagnosed only when an outbreak happens.

Health care providers should report all outbreaks of acute gastroenteritis, including suspected outbreaks of norovirus, to the appropriate state, local or territorial health department.

Health departments are encouraged to report all suspected and confirmed norovirus outbreaks through the National Outbreak Reporting System (NORS) and CaliciNet.

Surveillance Systems

NORS - National Outbreak Reporting System


NORS was launched by CDC in 2009 to collect information on outbreaks of foodborne, waterborne, and enteric disease that spread from person-to-person, animals, environmental surfaces, and other or unknown ways. Public health agencies can report all outbreaks of gastroenteritis, including norovirus illness, through this web-based system. This information is used to determine where norovirus outbreaks commonly occur, how the virus is spread, and specific food or water sources involved. In turn, this helps with identifying the best ways to prevent and control norovirus illness and outbreaks.

Definition of a Norovirus Outbreak

An outbreak of norovirus is defined as an occurrence of two or more similar illnesses resulting from a common exposure that is either suspected or laboratory-confirmed to be caused by norovirus.


CDC developed CaliciNet in 2009. It is a network of public health and food regulatory laboratories that submit norovirus sequences identified from outbreaks into a national database. The information is used to link norovirus outbreaks that may be caused by common sources (such as food), monitor trends, and identify emerging norovirus strains. As of February 2012, public health laboratories in 25 states have been certified by the CDC to participate in CaliciNet. States that are not yet certified may contribute through designated CaliciNet outbreak support centers, including the CDC.

Top of Page

Other Surveillance Systems

CDC is using New Vaccine Surveillance Network (NVSN) and Foodborne Diseases Active Surveillance Network (FoodNet) to do norovirus testing on patients with gastroenteritis. This will help generate new estimates of norovirus illness and monitor trends over time.


Top of Page

Images and logos on this website which are trademarked/copyrighted or used with permission of the trademark/copyright or logo holder are not in the public domain. These images and logos have been licensed for or used with permission in the materials provided on this website. The materials in the form presented on this website may be used without seeking further permission. Any other use of trademarked/copyrighted images or logos requires permission from the trademark/copyright holder...more

External Web Site Policy This graphic notice means that you are leaving an HHS Web site. For more information, please see the Exit Notification and Disclaimer policy.

Contact Us:
  • Centers for Disease Control and Prevention
    1600 Clifton Rd
    Atlanta, GA 30333
  • 800-CDC-INFO
    TTY: (888) 232-6348
    Contact CDC-INFO The U.S. Government's Official Web PortalDepartment of Health and Human Services
Centers for Disease Control and Prevention   1600 Clifton Rd. Atlanta, GA 30333, USA
800-CDC-INFO (800-232-4636) TTY: (888) 232-6348 - Contact CDC–INFO
A-Z Index
  1. A
  2. B
  3. C
  4. D
  5. E
  6. F
  7. G
  8. H
  9. I
  10. J
  11. K
  12. L
  13. M
  14. N
  15. O
  16. P
  17. Q
  18. R
  19. S
  20. T
  21. U
  22. V
  23. W
  24. X
  25. Y
  26. Z
  27. #