The very contagious norovirus mostly occurs in closed and crowded environments, e.g. on cruise ships and in schools, where the infection spreads very rapidly. The virus is normally transmitted through contaminated water, food or an infected person. Stomach or intestines or both get inflamed which results in nausea, diarrhea, vomiting, and abdominal pain. Most people recover completely without treatment. However, for young children and older adults, the virus tends to be more serious.
Signs of the infection normally start 24 to 48 hours after the person is exposed to the norovirus for the first time. They may include:
- Slight fever
- Muscles aches
Although a few people with norovirus infection don’t display symptoms, they are still contagious and can spread the virus to another person. The signs normally last between one and three days. Quite often, the patient continues to shed virus in his/her feces for up to three days after recovery.
The noroviruses are shed in the feces of humans and animals that are infected. In general, they are transmitted by eating contaminated food (e.g. raw or undercooked oysters and raw fruits and vegetables), drinking contaminated water, touching first contaminated objects and then nose, eyes, mouth, or by having contact with an infected person (e.g. shaking hands or closer contact). Since the viruses are very resistant to many disinfectants and extreme temperatures, it’s very difficult to destroy them. People with a weakened immune system are especially susceptible to catching noroviruses.
There's no treatment for the infection. In general, recovery depends on the health of the patient’s immune system. In most people, the illness normally disappears within a few days.
However, it's important to replace lost fluids. If a patient is not able to drink enough liquids containing minerals and electrolytes to prevent dehydration, he/she probably has to receive fluids intravenously. The physician might also recommend anti-diarrhea medication if the affected person is younger than 65 years.
Proper washing and disinfecting of the hands after having been to the bathroom as well as general cleanliness are effective methods for reducing the transmission of the norovirus. In addition, it’s advisable to cook certain food thoroughly in order to wipe out norovisus. Especially raw fish and seafood often contain the virus.