Diagnosis of gastrointestinal disease (diarrhea or vomiting) caused by norovirus genogroups 1 and 2
This test should not be used as a test-of cure
1. Collect fresh feces and place in preservative within 1 hour of collection.
2. Visibly formed feces are not consistent with Norovirus gastrointestinal disease and should not be submitted for testing.
A positive result suggests that norovirus is the cause of gastrointestinal disease (diarrhea or vomiting); however, in certain patients (eg, immunocompromised hosts), norovirus may be shed for weeks to months in the absence of symptoms.
This test should not be used as a test-of-cure, due to the fact that norovirus nucleic acid may be detected in patients for weeks to months following the resolution of symptoms.
A negative result suggests that norovirus is not the cause of gastrointestinal disease (diarrhea or vomiting); however, viral nucleic acid may be present at a level that is below the limit of detection for this test. The results should be interpreted in the context of the patient's clinical presentation and other laboratory findings.
Noroviruses, previously known as Norwalk-like viruses, are highly contagious RNA viruses that cause acute gastroenteritis (diarrhea, vomiting). Although 6 genogroups of norovirus have been identified, only 3 genogroups (genogroup: G1, G2, and G4) cause disease in humans. Furthermore, the majority of outbreaks have been associated with G1 and G2, with G2 being most common.
Noroviruses are transmitted through close, personal contact with an infected individual or via the fecal-oral route, in which the virus becomes ingested in contaminated food or water. These viruses are extremely contagious, with fewer than 20 virions being able to cause disease.
Once infected, the incubation period is typically short, between 24 and 72 hours. The onset of symptoms is abrupt, with vomiting and watery nonbloody diarrhea being common. Patients may also experience a low-grade fever, as well as headache and mild body aches.
The diagnosis of norovirus infection can often be made on clinical grounds, and symptoms generally resolve in 24 to 48 hours. However, in certain patients, especially those who are immunocompromised or hospitalized, laboratory testing may be indicated for infection control purposes and to limit the use of antibiotics. Testing of diarrheal feces by real-time polymerase chain reaction (PCR) allows for a rapid and sensitive means of detecting and differentiating norovirus G1 and G2 in clinical stool samples.
A positive result indicates that nucleic acid (RNA) from norovirus genogroups 1 and/or 2 was present in the clinical specimen.
A negative result suggests that nucleic acid (RNA) from norovirus genogroups 1 or 2 was absent in the clinical specimen.