Everything you need to know about norovirus and other vomiting bugs
Certain clues can help you identify which bug is making you sick and when you can expect to recover.
- 19 December 2024
- 5 min read
- by Linda Geddes
Stomach cramps, vomiting, diarrhoea: the sudden onset and violence with which the symptoms of gastroenteritis often present themselves can be alarming, not to mention dangerous for certain groups of people.
But gastroenteritis – inflammation of the stomach and/or intestines – can have many causes, and knowing which one is making you sick has implications for how you should behave and how long your illness is likely to last.
Gastroenteritis is usually a short-lived illness. Viruses or bacteria are the most common culprits, but parasites and certain drugs or chemicals can also trigger the condition.
Rotavirus
Most cases of gastroenteritis in children are triggered by a virus called rotavirus the leading cause of severe diarrhoea in young children globally.
Although vaccines have dramatically reduced deaths and hospital admissions in countries where they've been introduced, rotavirus remains a common cause of severe watery diarrhoea, vomiting, fever and stomach cramps in children under the age of five and should be considered a likely cause of such symptoms in babies and young children – particularly if they haven't been vaccinated.
Symptoms typically start two days after exposure to the virus and can last for three to eight days. Rotavirus is most common during winter or early spring in temperate climates such as the US or Northern Europe, but occurs year-round in tropical climates.
Older children and adults can also catch and get sick from rotavirus, although adults tend to have milder symptoms. However, gastroenteritis is more commonly caused by norovirus or food poisoning in this group.
Norovirus
Norovirus – also known as the winter vomiting bug – is extremely contagious, with symptoms typically starting 12-48 hours after exposure to the virus. It follows a similar seasonal pattern to rotavirus, but tends to be over more quickly, with symptoms usually only lasting for one to three days.
Alcohol-based hand gel is not very effective against norovirus, so regular handwashing with soap is the best means of prevention.
For adults experiencing a short-lived and often violent stomach bug, norovirus should be a prime suspect – especially if you've been in contact with someone who has recently had similar symptoms. However, food poisoning is another candidate (see below).
Both norovirus and rotavirus are spread by getting tiny particles of vomit or faeces in your mouth, which can happen by touching an infected person or touching surfaces, objects or food that have been contaminated by an infected person and then touching your mouth or eating without washing your hands.
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Contaminated drinking water or recreational water (such as swimming pools), is another potential source of infection, so people with diarrhoea should avoid swimming.
Rotavirus can also be spread through coughing and sneezing, while norovirus can become aerosolised when people vomit or have diarrhoea. These infectious particles could then be inhaled and swallowed by others or land on surfaces and hands. Alcohol-based hand gel is not very effective against norovirus, so regular handwashing with soap is the best means of prevention.
Food poisoning
Food poisoning can be triggered by many different viruses, bacteria, parasites and bacterial toxins and can strike within hours of ingesting contaminated food or drink – most commonly raw or undercooked food or food that hasn't been stored correctly. It can take days or even several weeks for symptoms to develop, depending on the cause.
Bacillus cereus [...] can strike within 30 minutes. E.coli [...] typically strikes after three to four days. Hepatitis A [...] can take 15 to 50 days to trigger illness.
For instance, Bacillus cereus, a bacterium found in foods such as rice, soup or meat that has sat out at room temperature too long, can strike within 30 minutes.
E.coli, which is found in raw or undercooked meat, unpasteurised milk, juice or soft cheeses, and fresh fruits and vegetables, typically strikes after three to four days.
Hepatitis A, found in raw and undercooked shellfish, fresh fruits and vegetables and other uncooked food, can take 15 to 50 days to trigger illness.
Another sign that someone's symptoms may be the result of food poisoning is that they often disappear within a day – although, depending on the cause, they can persist for several days or weeks.
Treatment
Because the symptoms are so similar, it is often very difficult to know what is making someone sick. However, in most cases, the symptoms can be treated at home, with rest and drinking adequate amounts of fluids to avoid dehydration. Because children can become dehydrated more quickly, they should be given oral rehydration salts mixed with water.
Since the biggest risk is dehydration, people should be aware of signs and symptoms such as excessive thirst, a dry mouth, producing little or no urine or deep yellow urine, and experiencing severe weakness, dizziness or lightheadedness.
Advice on when to seek medical attention for gastroenteritis varies by country, so you should check the situation where you live.
However, since the biggest risk is dehydration, people should be aware of signs and symptoms such as excessive thirst, a dry mouth, producing little or no urine or deep yellow urine, and experiencing severe weakness, dizziness or lightheadedness.
Signs of dehydration in children and infants can also include seeming very irritable, sleepy or unresponsive; crying without tears; having a sunken soft spot on the top of their head (infants); having pale or mottled skin or cold hands and feet.
Having a high fever, or vomiting blood and/or passing bloody diarrhoea may also be signs of severe illness.
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