Norovirus is usually diagnosed based on symptoms, but when tests are done they look for the virus or its genetic material in stool (and sometimes vomit, food, water, or surfaces). These tests are typically done in hospital or public health laboratories, not at home.
Main lab test
The primary test is a molecular test called RT‑qPCR (reverse‑transcription quantitative PCR), which detects tiny amounts of norovirus RNA in a sample and is considered the preferred method because it is very sensitive and specific. A stool sample is usually collected in a clean container and sent to a lab that runs this assay, often as part of a multiplex “GI panel” that checks for several stomach bugs at once.
Rapid antigen tests
There are also rapid enzyme immunoassays (EIA) or lateral‑flow tests that detect norovirus antigens in stool and can give results quickly. These are easier to use but significantly less sensitive, so negative results often need confirmation with PCR, especially during outbreak investigations.
Other, less common methods
Electron microscopy can visually identify norovirus particles in stool but is rarely used now because it needs specialized equipment and is less sensitive than PCR. Specialized labs may also “genotype” norovirus by sequencing PCR products, which helps link cases in outbreaks and track new strains rather than diagnose routine individual cases.
