Digestive Health

Updated 04 May 2017

Causes of gastroenteritis

The most common cause of gastroenteritis is a virus.


Many different viruses may cause gastroenteritis.

Some of these include:

- Rotaviruses: This is the most common cause of gastroenteritis in children and is especially prevalent in winter.

- Caliciviruses (noroviruses, sapoviruses): With the introduction of the rotavirus vaccination, the  norovirus is now becoming the main cause of acute gastroenteritis in children.

- Certain Adenoviruses

- Astroviruses

Gastroenteritis can furthermore be caused by:

- Bacteria: Common bacterial causes include Campylobacter, Shigella, Salmonella or certain strains of Escherichia coli. Some bacteria produce toxins that cause food poisoning

- Parasites e.g. Giardia

- Certain medications

- Toxins in plants (including mushrooms) or other foods like "red tide" in shellfish

As we get older, we develop immunity to the more common viruses and bacteria in our environment. This means that despite regular exposure, we are no longer vulnerable to many of them.

These micro-organisms are usually acquired directly or indirectly from another infected person. However, some are present in soil, water and even air. Animals (both livestock and pets), may be a source of infection with some of the micro-organisms that cause gastroenteritis.

If you have a child with ongoing gastrointestinal symptoms, it may be worth considering that he or she is lactose intolerant (an intolerance of milk sugar).

Who gets it and who is at risk?

Anyone can get gastroenteritis. In fact, no child will escape an episode or two of gastroenteritis, however good his or her socioeconomic circumstances.

Certain groups are more vulnerable to getting gastroenteritis. These include:

- Babies and young children, as their immune systems are still developing

- Seniors who have weakened immune systems

- Gastroenteritis often spreads easily in underprivileged communities that have bad sanitation and poor food storage facilities

- People in impoverished communities have a high incidence of gastroenteritis

- Gastroenteritis is more dangerous for those with poor nutrition, and is a primary cause of death in babies and young children in African countries.

- People with immunodeficiency diseases such as AIDS have a higher incidence of gastroenteritis.

- Travellers who come into contact with local bacteria and viruses, against which their immune systems do not have pre-existing defences.

Misunderstood causes

The germs that cause gastroenteritis usually enter your system through your mouth. There is an incubation period of a few hours to a few days before the illness becomes apparent.

Because infection may occur a while before becoming symptomatic (appearing sick), people who contract gastroenteritis often incorrectly assume that they got food poisoning from the last meal they consumed. While this may be the case, there is no way to prove it without analysing the food itself.

Read more:

Symptoms of gastroenteritis

Treating gastroenteritis

Diagnosing gastroenteritis

Reviewed by Dr Karin Richter, MMed Path (Medical Virology), FC Path(SA) Viro, Dip HIV Man (SA), Dip Obst (SA), MBChB , Clinical Virologist, Senior Lecturer, Department of Medical Virology, University of Pretoria, Faculty of Health Sciences, and Consultant Pathologist, Tshwane Academic Division, National Health Laboratory Services (NHLS)

Previously reviewed by Dr EftyhiaVardas BSc (Hons), MBBCh, DTM&H, DPH, FC Path (Virol), MMed (Virol), Clinical Virologist, Director HIV AIDS Vaccine Division.  


Ask the Expert

Digestive Health Expert

Dr. Estelle Wilken is a Senior Specialist in Internal Medicine and Gastroenterology at Tygerberg Hospital. She obtained her MBChB in 1976, her MMed (Int) in 1991 and her gastroenterology registration in 1995.

Still have a question?

Get free advice from our panel of experts

The information provided does not constitute a diagnosis of your condition. You should consult a medical practitioner or other appropriate health care professional for a physical exmanication, diagnosis and formal advice. Health24 and the expert accept no responsibility or liability for any damage or personal harm you may suffer resulting from making use of this content.

* You must accept our condition

Forum Rules