Chapter 3

How is Norovirus Infection Diagnosed?

Norovirus can be detected in an infected person’s stool or vomit through laboratory testing.

Diagnosis of norovirus illness is based on the combination of symptoms, particularly the prominence of vomiting, fever, and short duration of illness. If a known norovirus outbreak is in progress, public health officials may obtain specimens from ill individuals for testing in a lab.

Lab tests consist of identifying norovirus under an electron microscope. A reverse transcriptase polymerase chain reaction test (RT-PCR assay) can also detect norovirus in food, water, stool samples, and on surfaces. These tests isolate and replicate the suspected virus’s genetic material for analysis. An ELISA can also be performed, which detects antigens; they are easier to perform than RT-PCR, but less sensitive and can also result in many false negatives.