Worldwide, norovirus is the leading cause of acute gastroenteritis, with symptoms including both diarrhea and vomiting. Approximately 20% cases of acute gastroenteritis are caused by norovirus. Each year in the US, it causes 19-21 million illnesses and contributes to 56,000-71,000 hospitalizations and 570-800 deaths. Norovirus is a very contagious virus. You can get norovirus from an infected person, contaminated food or water, or by touching contaminated surfaces. Norovirus is also the most common cause of foodborne-disease outbreaks in the United States. Human noroviruses cannot be grown in cell culture, so diagnostic methods focus on detecting viral RNA or antigen.
PCR assays are the preferred laboratory method for detecting norovirus. These assays are very sensitive and can detect as few as 10 to 100 norovirus copies per reaction.
Rapid commercial enzyme immunoassays (EIAs), that detect norovirus antigen have recently been developed. However, these kits have poor sensitivity (50%), are not recommended by the CDC for diagnosing norovirus infection in sporadic cases of gastroenteritis, and should not replace molecular methods during outbreak investigations.