ELISA diagnosis of a gastrointestinal norovirus outbreak in a nursery

The incidence of gastrointestinal outbreaks caused by Norovirus in children has been underestimated. This fact is mainly due to the difficulty in the availability of adequate diagnostic procedures (electronic microscopy and Reverse Transcriptase Polymerase Chain Reaction [RTPCR]). The new Enzyme-Linked Immunosorbent Assay (ELISA) methods for the detection of viral antigens in stools represent a promising diagnostic alternative. The objective of this study was to describe the application of an ELISA technique in the investigation of an outbreak by Norovirus in a day care center. In September 2003 several cases of gastroenteritis in children attending a day care center were communicated. The outbreak affected to 15 out of 64 exposed children. The symptomatology was vomits (100%), abdominal pain (66%), nauseas (40%) and diarrhoea (40%). The duration of the symptoms was 3 days (median 2 days). Three patients required hospitalisation and all of them improved with symptomatic treatment. Three faecal samples of three patients were studied. The presence of Salmonella sp, Shigella sp and Campylobacter sp was discarded by coproculture. The investigation of Norovirus, Rotavirus, Adenovirus and Astrovirus was carried out by specific ELISAs (IDEIA NLV, IDEIA Rotavirus, IDEIA Adenovirus e IDEIA Astrovirus; Dako Ltd, Ely UK). In the three processed samples were obtained positive results for Norovirus. These results were confirmed by using RT-PCR. The results for all other pathogens were negative. The wide application of similar ELISA techniques will allow defining the role of Norovirus as agents of gastrointestinal outbreaks among children in our environment.