It is not possible to diagnose rotavirus infection by clinical presentation or nonspecific laboratory tests. Enzyme immunoassay and latex agglutination assays for group A rotavirus antigen detection in stool are available commercially. Both assays have high specificity, but false-positive results and nonspecific reactions can occur in neonates and in people with underlying intestinal disease. Nonspecific reactions can be distinguished from true positive reactions by performance of confirmatory assays. Virus also can be identified in stool by electron microscopy and by specific nucleic acid amplification techniques.