Lateral-flow assay and time-resolved fluorescence technologies provide a sensitive tool for detecting norovirus particles in a sample. A flow-through assay device employs norovirus and norovirus G2 antibodies. The lateral-flow assay includes a conjugate pad having conjugated probes. The conjugated probes are particles modified with a binding member that is configured to bind with a norovirus. The particles also have a fluorescent label. A general method of detecting the virus includes (i) preparing a sample with contaminants, (ii) processing the sample and depositing it onto the assay device, and (iii) measuring the fluorescence signal.