Norovirus, sometimes referred to as the winter vomiting bug, is the most common cause of gastroenteritis. Norovirus infection causes your stomach or intestines or both to get inflamed. This leads to stomach pain, nausea, diarrhoea and vomiting. While they can strike year round, they’re more common in the winter, hence the tag “winter vomiting bug”.
It is common both in the developed and developing world. Those under the age of five are most often affected. It often occurs in outbreaks, especially among those living in close quarters. Norovirus infection occurs most frequently in closed and crowded environments such as hospitals, nursing homes, child care centres, schools and cruise ships.
Norovirus can be very unpleasant, but it’s not something to panic about. It usually clears up by itself in a few days.
Noroviruses are a group of viruses, previously known as Norwalk-like viruses, named after Norwalk, Ohio, where an outbreak occurred in 1972. Norovirus was probably first noticed by Dr. J. Zahorsky in 1929 and termed "winter vomiting disease." The name of the genus, Norovirus, was approved in 2002 by an international committee.
Noroviruses are usually spread by the faecal-oral route. This may be by contaminated food or water or person-to-person contact.
It may also spread via contaminated surfaces or through the air. They are highly contagious and fewer than twenty virus particles can cause an infection. Transmission can be aerosolized when those stricken with the illness vomit, and can be aerosolized by a toilet flush when vomit or diarrhoea is present. Infection can follow eating food or breathing air near an episode of vomiting, even if cleaned up. Vomiting, in particular, transmits infection effectively and appears to allow airborne transmission.
The viruses continue to be shed after symptoms have subsided and shedding can still be detected many weeks after infection. While you can shed the virus for up to 8 weeks, it is less and less infectious over time. In most cases, you can return to work or school after you have been symptom-free for 48 hours
Symptoms of Norovirus Infection
Signs and symptoms of norovirus infection include:
Abdominal pain or cramps
Watery or loose diarrhoea
Signs and symptoms usually begin 12 to 48 hours after first exposure to the virus and last one to three days. You may continue to shed virus in your faeces for up to two weeks after recovery. Viral shedding may last several weeks to several months if you have an underlying health condition.
Some people with norovirus infection may show no signs or symptoms. However, they are still contagious and can spread the virus to others.
For most people, norovirus infection clears up within a few days and isn't life-threatening. But in some people, especially children and older adults with compromised immune systems in hospitals or nursing homes, norovirus infection can cause severe dehydration, malnutrition and even death.
Warning signs of dehydration include:
Dry mouth and throat
Decreased urine output
Children who are dehydrated may cry with few or no tears. They may also be unusually sleepy or fussy.
When to see a doctor
Seek medical attention if you develop diarrhoea that doesn't go away within several days. Also call your doctor if you experience severe vomiting, bloody stools, abdominal pain or dehydration.
Risk factors for becoming infected with norovirus include:
Eating in a place where food is handled with unhygienic procedures
Attending preschool or a child care centre
Living in close quarters, such as in nursing homes
Staying in hotels, resorts, cruise ships or other destinations with many people in close quarters
Having contact with someone who has norovirus infection
Diagnosis is usually based on your symptoms. But norovirus can be identified by testing a stool sample. If you are immune-compromised or have other health problems, your doctor may recommend a stool test to confirm the presence of norovirus.
There is no specific treatment for norovirus infection, and recovery generally depends on the health of your immune system. Efforts involve supportive care such as drinking sufficient fluids or intravenous fluids. In most people, the illness usually resolves within a few days.
It's important to replace lost fluids. If you're unable to drink enough fluids to prevent dehydration, you may need to receive fluids intravenously.
Noroviruses, like other viruses, don't respond to antibiotics, which are designed to kill bacteria. No antiviral drug can treat noroviruses, but in healthy people, the illness should go away on its own within a couple of days.
Lifestyle and home remedies
If your family includes young children, it's a good idea to have commercially prepared oral hydration solution, such as Pedialyte, on hand.
Adults can drink sports drinks and broths.
Avoid drinking liquids that contain a lot of sugar, such as soft drinks and fruit juices, as well as alcohol and caffeinated beverages, which can dehydrate you further.
You can use over-the-counter medication such as paracetamol for any fever or aches and pains.
Also, adults can take anti-diarrhoeal and anti-emetic (anti-vomiting) medication. These aren't suitable for everyone though, so you should check the medicine leaflet or ask or your doctor for advice before trying them.
Get plenty of rest.
Smaller meals and a bland diet may help limit vomiting. Some foods to consider are:
Starches and cereals, such as potatoes, noodles, rice, bread or crackers
Norovirus infection is highly contagious, and anyone can become infected more than once. A vaccine does not exist. To help prevent its spread, good hygiene is the key to preventing a norovirus infection, especially when you are close to a lot of other people.
Wash your hands thoroughly, especially after using the toilet or changing a diaper. Alcohol-based cleansers are not as effective as soap and water.
Avoid contaminated food and water, including food that may have been prepared by someone who was sick.
Wash fruits and vegetables before eating.
Cook seafood thoroughly.
Dispose vomit and faecal matter carefully, to avoid spreading norovirus by air.
Disinfect virus-contaminated areas with a chlorine bleach solution. Wear gloves.
Wash any items of clothing or bedding that could have become contaminated separately on a hot wash to ensure the virus is killed.
Don't share towels and flannels.
Stay home from work, especially if your job involves handling food. You may be contagious as long as three days after your symptoms end. Children should stay home from school or child care.
Avoid travelling until signs and symptoms have ended.
Prognosis of Norovirus Infection
Norovirus infection typically resolves on its own without any adverse consequences in healthy people who receive adequate hydration and the prognosis is generally excellent.
There is no evidence to suggest that an infected person can become a long-term carrier of norovirus.
Also, most people don't have any long-term problems from the virus.