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NoroSTAT Data

Suspected and Confirmed Norovirus Outbreaks Reported by State Health Departments in Michigan, Minnesota, Ohio, Oregon, South Carolina, Tennessee, and Wisconsin to the National Outbreak Reporting System (NORS) by Week of Illness Onset, 2009-2015*†.

The number of norovirus outbreaks reported to NORS is typically higher in winter months, peaking in December, January, and February. However reported outbreaks in 2013-2014 peaked in April and in 2014-2015 peaked in March, with an additional increase in April.

See data table for this chart.

*Incomplete outbreak data from 2009-12 was supplemented with information from state health department records.

†Michigan and South Carolina joined the NoroSTAT network at the start of the 2015-16 reporting season; 2009-15 data from these states has been added for comparison.