Novel Surveillance Network for Norovirus Gastroenteritis Outbreaks, United States

Abstract

CaliciNet, the outbreak surveillance network for noroviruses in the United States, was launched in March 2009.As of January 2011, twenty state and local health laboratories had been certifi ed to submit norovirus sequences and epidemiologic outbreak data to CaliciNet.During the network's fi rst year, 552 outbreaks were submitted to CaliciNet, of which 78 (14%) were associated with foodborne transmission.A total of 395 (72%) outbreaks were typed as GII.4, of which 298 (75%) belonged to a new variant, GII.4 New Orleans, which fi rst emerged in October 2009.Analysis of the complete capsid and P2 region sequences confi rmed that GII.4 New Orleans is distinct from previous GII.4 variants, including GII.4 Minerva (2006b).N oroviruses are the primary cause of epidemic viral gastroenteritis and the leading cause of foodborne outbreaks in the United States (1-3).Although the course of disease is in most cases self-limiting, young, elderly, and immunocompromised persons are at risk for complications caused by severe vomiting and diarrhea (4-8).In addition to the clinical impact of norovirus disease, the economic effects in lost wages, time, and intervention procedures (e.g., clean-up costs and recalls) can be signifi cant (9-11).Although norovirus outbreaks occur year-round, they are more common during the winter months (12-14).Noroviruses are genetically classifi ed into 5 genogroups, GI-GV, with GI and GII strains responsible for most human disease (2,15).GII viruses can be further Novel Surveillance Network for Norovirus GastroenteritisOutbreaks, United States 1