CaliciNet is a national surveillance network of federal, state and local public health laboratories in the United States, coordinated by CDC. It follows outbreaks and sporadic cases of norovirus — and of its relative sapovirus — by reading the genetic makeup of the viruses that cause them. CDC launched it in 2009 to gather information on the norovirus strains behind outbreaks of gastroenteritis.
Why “calici”
Noroviruses and sapoviruses both belong to the family Caliciviridae, the caliciviruses, which cause diarrheal disease. The name comes from the cup-shaped hollows visible on the virus particles under an electron microscope.
How data reach the network
Participating laboratories use standardized protocols to work out the genetic sequence of the norovirus strain in each outbreak, then submit their results electronically to the CaliciNet database.
How a norovirus outbreak is reported through CaliciNet. Image from CDC’s page.
The database holds two kinds of information:
- norovirus sequences from outbreaks and sporadic cases of acute gastroenteritis in the United States; and
- basic epidemiologic data on each outbreak — how it spread, where it happened, and the demographics of the patients.
What the data are used for
Each new sequence is compared against those already in the database. That comparison helps CDC:
- link clusters of norovirus illness to a common source, such as contaminated food;
- standardize the way norovirus strains are typed;
- monitor the strains in circulation; and
- detect new strains as they emerge, such as GII.17[P17].
All of it serves one aim: to understand noroviruses better and to design ways of stopping them from spreading.
Who can see the data
Only the local, state and federal public health laboratories taking part in CaliciNet can access the database, and a certified laboratory needs CDC’s permission before using the data in a study. All submissions are made securely, and CDC does not release information about the specific people or facilities involved in an outbreak. Combined results reach public health professionals, health departments and the public through scientific publications, presentations and CDC’s website.
The laboratories
Membership is limited to U.S. public health laboratories — federal, state and local — that either complete CaliciNet’s certification, or work with a certified CaliciNet Outbreak Support Center or with CDC’s National Calicivirus Laboratory to report their outbreak data. A certified laboratory must pass a proficiency test twice a year to keep its status.
As of January 2026, 34 laboratories in 29 states and the District of Columbia were certified. Laboratories without certification can send outbreak specimens for norovirus typing to an Outbreak Support Center or to the National Calicivirus Laboratory.
When it is not norovirus
Three CaliciNet laboratories — the state health laboratories of California, Minnesota and Oregon — act as Unexplained Viral Diarrhea Outbreak Support Centers. They take stool specimens from outbreaks that tested negative for norovirus and look for other intestinal viruses: rotavirus, sapovirus, astrovirus and adenovirus. Samples that test positive are genotyped; those that test negative go on to next-generation sequencing in search of an unknown cause.
Further testing of 244 norovirus-negative outbreaks, September 2013–June 2018. Image from CDC’s page.
Links to other systems
CDC joins CaliciNet’s laboratory results with the clinical and epidemiologic data in the National Outbreak Reporting System (NORS), which collects reports on all enteric disease outbreaks, norovirus included, and on waterborne outbreaks of non-enteric disease. Together they strengthen outbreak investigations and the tracking of trends.
Several CaliciNet laboratories also take part in NoroSTAT, a CDC system that draws on NORS and CaliciNet to make norovirus outbreak reporting faster, more complete and more consistent, so outbreak activity can be evaluated and compared quickly.
Funding
CaliciNet is supported by CDC’s Food Safety Program through the Epidemiology and Laboratory Capacity (ELC) Cooperative Agreement, which builds the capacity of state, local and territorial health departments to detect, respond to, prevent and control infectious diseases, known and emerging.
Sources
Based on "CaliciNet Surveillance Network" (Reporting and Surveillance for Norovirus), Centers for Disease Control and Prevention; a work of the United States government in the public domain. The source page names four states as homes of Outbreak Support Centers but elsewhere says there are five, so neither the number nor the list is given here.
Licence: CC0 1.0 (public domain) · Adapted from www.cdc.gov
1
0
0
0
Comments
