National surveillance system on tap for norovirus outbreaks

Spike in outbreaks likely an underestimate

Noting that a national spike in norovirus outbreaks likely represents an underestimate, the Centers for Disease Control and Prevention is setting up a national surveillance system as the bane of cruise ships moves aggressively into hospitals and long-term care settings.

"Currently we are trying to come up with a surveillance system for norovirus and we hope to have it up and running by the end of the year or certainly by the beginning of 2008," says Jacqueline Tate, PhD, a CDC epidemic intelligence service officer who investigated the outbreaks.

Foodborne outbreaks of acute gastroenteritis (AGE) are reportable, but no national surveillance system exists for AGE or norovirus outbreaks that are transmitted from person to person. In addition, reporting methods and completeness of reporting vary substantially by state, the CDC reports. During October-December 2006, only 29% of all reported AGE outbreaks in 24 states had laboratory confirmation of norovirus. States such as Wisconsin that routinely test specimens from outbreaks determined that a high proportion were attributable to norovirus.

In June 2006, the Council for State and Territorial Epidemiologists passed a resolution stating that all AGE outbreaks should be reportable nationally, regardless of mode of transmission (i.e., foodborne or person to person). This will be implemented in through the National Outbreak Reporting System. In addition, development and application of new, easy-to-use norovirus assays for routine clinical practice could better define the prevalence of norovirus among persons with AGE who seek health care services. CaliciNet, a centralized database at CDC, is used to collect and compare norovirus sequences to identify emergent strains, track more virulent strains in real time, and determine the role of contaminated foods in their emergence; this database soon will be widely accessible to state and local health departments, the CDC reports.1


  1. Centers for Disease Control and Prevention. Norovirus activity — United States, 2006-2007. MMWR 2007; 56(33): 842-846.