When people complain of gastrointestinal illness or the stomach flu, the illness is usually Norovirus.

Norovirus illness usually develops 24 to 48 hours after ingestion of contaminated food or water. Symptoms typically last a relatively short amount of time, approximately 24 to 48 hours. These symptoms include nausea, vomiting, diarrhea, and abdominal pain. Headache and low-grade fever may also accompany this illness. People infected with norovirus usually recover in two to three days without serious or long-term health effects.

Diagnosis of norovirus illness is based on the combination of symptoms, particularly the prominence of vomiting, little fever, and the short duration of illness. Although symptoms usually only last one to two days in healthy individuals, norovirus infection can become quite serious in children, the elderly, and immune-compromised individuals. In some cases, severe dehydration, malnutrition, and even death can result from norovirus infection, especially among children and among older and immune-compromised adults in hospitals and nursing homes.

There is no specific treatment available for norovirus. In most healthy people, the illness is self-limiting and resolves in a few days; however, outbreaks among infants, children, elderly, and immune-compromised populations may result in severe complications among those affected. Recent research has investigated the potential for developing a norovirus vaccine. Researchers indicate that coming up with a norovirus vaccine would be like vaccinating for influenza, by using screening to select for the most prevalent strains.