ISGEV epidemiological data on human enteric viruses are generated through hospital-based surveillance. Hospitalized patients usually are only the tip of the iceberg, as only a limited part of enteric infections require medical care or hospitalization. Only 0.28-0.35% of norovirus illnesses result in hospitalization, according to USA data (source CDC).

Samples are collected from pediatric wards of three hospitals located in Northern Italy (Parma University Hospital), Southern Italy (Bari Pediatric University Hospital “Giovanni XXIII”) and the island of Sicily (Palermo ARNAS Civic Hospital). The three hospitals serve a cumulate pediatric (0-14 years) population of 426,569 newborns, infants and children (official population figures at January 1st, 2015), i.e. about 5% of the total Italian pediatric population. During the year 2015, in the pediatric population monitored by ISGEV network the hospitalization rate for gastro-enteric disease was  1: 207  (2063 patients), and norovirus accounted for 10.7% (220 cases) of the hospitalizations.

Stool samples are collected on the day of hospital admission from all patients aged less than 15 years who fulfill the case definition. Case definition includes young patients presenting with vomiting (>1 episode/day), diarrhea (>3 stools/day), abdominal pain or fever (T≥38°C) and/or requiring rehydration therapy.

The samples are analyzed using molecular assays for virus detection and characterization. The diagnostic panel includes the major viral enteric pathogens (rotavirus, astrovirus and norovirus) and other viral and bacterial agents. Web-based typing tools (Noronet) are used for characterization of noroviruses.