Gastroenteritis (Stomach Flu)

Gastroenteritis is an irritation and inflammation of the digestive tract.

It is also commonly referred to as Stomach flu. Sometimes it is referred to simply as 'gastro'.

Its onset is characterised by fever, vomiting or diarrhoea. It is caused by an infectious virus, bacteria or parasite.

Despite Gastroenteritis being often referred to as stomach flu, it is not related to or caused by the influenza virus.

The illness usually begins with an acute onset, normally lasting less than 10 days and self-limiting.

If the inflammation is limited to the stomach, the term gastritis is used, and if the small bowel alone is affected it is enteritis.

Bacterial Causes

Bacterial causes are less common in developed countries. Campylobacter jejuni is responsible for 5-10% of cases, whereas Salmonella species, Shigella species, and various pathogenic types of Escherichia coli account for a small percentage.

Cholera, caused by Vibrio cholerae is another important cause of acute diarrhoeal illness and subsequent death in the developing world.


Outbreaks of Giardia lamblia can cause dehydrating diarrhoea in infants. Cryptosporidium is known to cause 1-4% of cases of acute diarrhoea in hospitalised infants.

Viral Gastroenteritis (Stomach Virus)

Viral gastroenteritis is highly contagious. It can be very serious when the patient cannot drink sufficient fluids to return what is lost through vomiting and diarrhoea. This is especially so in infants, children, the elderly, and people whose immune system is compromised or weak.

The viruses that cause viral gastroenteritis damage the cells in the lining of the small intestine. As a result, fluids leak from the cells into the intestine and produce watery diarrhoea.

Four types of viruses can cause stomach virus infections:

  • Rotavirus: This is the principal cause of stomach virus among children aged 3 to 15 months. It is also the most common cause of diarrhoea in children under the age of 5 years.

    The symptoms of rotavirus infection appear 1 to 2 days after contact with the virus. Rotavirus causes vomiting and watery diarrhoea for 3 to 8 days. The patient also experiences fever and abdominal pain.

    Rotavirus can infect adults who are in close contact with infected children. The symptoms in adults are moderate.

  • Astrovirus: This also usually infects infants, young children, and the elderly. It is very active during the winter months. Its main symptoms are vomiting and diarrhoea. The symptoms appear within 1 to 3 days of coming into contact with the virus.

  • Adenovirus: This occurs primarily in children under the age of 24 months. It causes vomiting and diarrhoea. The symptoms normally appear 1 week after exposure to the virus. The adenovirus infections occur throughout the year.

  • Caliciviruses: This causes infection in people of all ages. These viruses are of four types. The noroviruses are the most common responsible for infecting most people. They are usually responsible for epidemics of viral gastroenteritis. Symptoms include vomiting, diarrhoea, fatigue, headache, and occasionally muscle aches. These symptoms appear within 1 to 3 days of contact with the virus.

    Transmission of Stomach Virus

    People with unwashed hands usually transmit viral gastroenteritis. The stomach virus is extremely infectious.

    You can get the viruses through close contact with infected persons. This can be through sharing their food, drink and eating utensils. Eating food or taking drinks contaminated with the virus will also cause stomach virus.

    People who no longer have symptoms may still be contagious. The virus is in their gut for up to 2 weeks after they recover from their illness. In addition, infected persons may not have the symptoms. Such people can also spread the infection. Stomach virus outbreaks can occur in homes, childcare centres, schools, nursing homes, cruise ships, camps, dormitories, restaurants etc.


    Viral gastroenteritis diagnosis is based on the symptoms and a physical examination.

    The doctor may ask for a stool sample to test for rotavirus. He will also be able to rule out bacteria or parasites as the cause of your symptoms.

    Gastroenteritis Symptoms

    Germs which cause gastroenteritis will normally get into your body through your mouth.

    It can take 1 - 2 days (4 to 48 hours) before the symptoms begin. The symptoms may include the following;

  • Nausea
  • Vomiting
  • Fever
  • Abdominal cramps
  • Diarrhoea
  • Fatigue
  • Muscle aches
  • Headache
  • Loss of appetite
  • Dehydration

    Gastroenteritis may last up to 10 days depending on which virus causes the illness.

    Prevention of Gastroenteritis

    It is of great importance to thoroughly wash your hands before eating or preparing food if stomach flu is to be avoided.

    It is also vital to disinfect the surface where food is being prepared or stored.Avoid water or food which is contaminated or thought to be contaminated.

    Stomach flu is contagious. The viruses that cause gastroenteritis are easily spread through close contact with infected persons. Therefore avoid sharing food, water or utensils with infected persons.

    The elderly, infants and the disabled are at very high risk of dehydration and may need to be hospitalised to prevent enormous dehydration.

    There is no vaccine or medicine that prevents the flu. It is possible to recover fully from gastroenteritis without long-term problems.

    Likely Stomach Flu/Virus Complications

    Dehydration is the most pressing complication caused by gastroenteritis. It needs prompt rectification by a clinician if severe.

    Febrile convulsions are common in children, especially with rotavirus infections.

    Sugar malabsorption is the most common complication in infants.

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