Evaluation of a commercial enzyme immunoassay for detection of norovirus in outbreak specimens.

The aim of the study presented here was to use faeces from 41 gastroenteritis outbreaks (130 specimens) in Victoria, Australia, to evaluate the sensitivity and specificity of the RIDASCREEN norovirus enzyme immunoassay (EIA) kit relative to reverse transcription-polymerase chain reaction and/or electron microscopy. Seven specimens known to contain sapovirus, adenovirus, astrovirus and rotavirus were also tested. For single-specimen diagnosis the kit gave a specificity and sensitivity of 47% and 71%, respectively; altering the positivity cut-off to give a specificity of 73% reduced the sensitivity to 44%. Thus, the kit cannot be recommended for single-specimen diagnosis. One specimen containing adenovirus but not norovirus was identified as non-specifically positive by the EIA kit. If the criterion used for outbreak positivity was at least one EIA-positive specimen per outbreak, the kit's outbreak sensitivity was 94% but the outbreak specificity was only 60%.