Norovirus is a leading cause of acute gastroenteritis in people of all ages worldwide. Norovirus causes inflammation of the stomach, intestines or both. Noroviruses are members of a group of viruses called caliciviruses, known previously as “Norwalk-like viruses.” They were named after the original Norwalk strain, which caused an outbreak of gastroenteritis in a school in Norwalk, Ohio in 1968.
Norovirus and rotavirus are different viruses that cause stomach problems, like nausea, vomiting, and diarrhea. Norovirus is more common in adults, while rotavirus tends to affect infants and young children. There is a vaccine to prevent rotavirus, but there is currently no licensed vaccine to prevent norovirus.
According to the U.S. Centers for Disease Control and Prevention (CDC), worldwide, about one out of every five cases of acute gastroenteritis that leads to diarrhea and vomiting is caused by norovirus. Annually causing an estimated 685 million cases. About 200 million cases are seen among children under 5 years old, leading to an estimated 50,000 child deaths every year, mostly in developing countries.
The virus is spread primarily from one infected person to another by the fecal-oral route. This may be through contaminated food or water or person-to-person contact. It may also spread via contaminated surfaces. Infected kitchen workers can contaminate a salad or food during preparing, if they have the virus on their hands. Approximately 14–23 percent of all norovirus illnesses are attributed to foodborne transmission.
Norovirus illness usually begins 24 - 48 hours after exposure, but can appear as early as 10 hours after exposure. Symptoms usually include nausea, vomiting, diarrhea, and stomach cramping. Sometimes people have a low-grade fever, headache, and a tiredness. The illness is usually brief, with symptoms lasting 1 or 3 days.
People infected with norovirus are contagious from the moment they begin feeling ill to at least 3 days after recovery. Some people may be contagious for as long as 2 weeks after recovery. Therefore, good hand washing is important.
Norovirus disease is usually not serious, but people may feel very sick. Most people get better within 1 or 2 days, and have no long-term health effects from the illness. Sometimes people are unable to drink enough liquids to replace what they lose from vomiting and diarrhea, and they can become dehydrated and need to see a doctor. This problem usually occurs only among the very young, the elderly, and persons with weakened immune systems.
Prevention involves proper hand washing and disinfection of contaminated surfaces. Management of norovirus involves supportive care such as drinking Oral rehydration solution, although other drinks without caffeine can help. Oral fluid and electrolyte replacement is generally adequate for the treatment of norovirus infections. Sometimes dehydration can lead to serious problems. Children who are dehydrated may cry with few or no tears and be unusually sleepy or fussy. Severe dehydration may require hospitalization for treatment with fluids given through intravenous.
Persons working in day-care centers or nursing homes should pay special attention to residents who have symptoms of norovirus. The virus can spread quickly in these types of facilities. During outbreaks, use soap and water for hand hygiene after providing care or having contact with patients suspected or confirmed with norovirus gastroenteritis.
Diagnostic testing is available for norovirus. They can be used to test stool, vomitus, food, water, and environmental specimens for norovirus. preventing norovirus disease through vaccination is an appealing strategy. Currently, several norovirus vaccines are in development stage.