Acute diarrhoea or Gastroenteritis or food poisoning

Acute diarrhoea or Gastroenteritis or food poisoning

Dr. Widjaja Luman
Consultant Gastroenterologist and General Physician
B Sc (St. Andrews), MB ChB (Man), MRCP (UK), M.D. (Edin),
CCST (UK), FRCP (Edin)

(Ahli penyakit pencernaan dan hepar)



Gastroenteritis or food poisoning is a frequent cause of acute diarrhoea in the community. “Acute diarrhoea” means severe sudden onset of diarrhoea. It is due to ingestion of food or water contaminated by bacteria or viruses. Food is a rich culture medium for bacteria, especially if it is improperly cooked and mishandled, or left unrefrigerated for long period before consumption. Warm temperature stimulates bacteria to grow and multiply in the food. Contaminated water also serves a vehicle for outbreaks of food poisoning.


What are the causes for food poisoning?

The causes for food poisoning can be bacterial or viral agents. Common bacterial agents are Salmonella species, Shigella species, Escherichae coli, Bacillus cerues, Campylobacter species and staphylococcal aureus.

Some bacteria cause the symptoms of food poisoning by releasing toxins. These toxins can be heat resistant and can thus not be destroyed by reheating (such as frying). Other bacteria cause symptoms by directly invading and causing damage to the gut wall.

Viral gastroenteritis is estimated to account for 40% of hospital admissions due to food poisoning. Viruses are easily transmitted through water and through contaminated and improperly cooked seafood such as clams, oysters. Hepatitis A can present as food poisoning during the early stages of the disease (see related article on hepatitis A on this website).


What are the symptoms?

The clinical features of food poisoning are profuse vomiting, diarrhoea, crampy abdominal pain within 8 to 24 hours after ingestion of the contaminated foods. Fever may or may not be present. Severity of diarrhoea can be mild and self limiting for one or two days.   Or sufferers can experience severe ‘dysentery’ like syndrome with passage of watery stools many times per day. The stool may contain blood, mucus and pus.


What can I do to treat myself with food poisoning?

Mid diarrhoea can usually be treated effectively by self medication. The mainstay of therapy in mild food poisoning is adequate hydration. Illness is usually self limiting and does not require any specific medical therapy. The overwhelming majority of adults have mild diarrhoea that will not lead to dehydration provided adequate fluids is taken. Hydration can be achieved by drinking boiled barley or rice water with sprinkle of salt. This formulation helps to increase water absorption across the gut wall. An easier way is to consume commercially available oral rehydration salts in tablets or sachets form ( Rehidrat, Dioralyte ). This tablets can be drunk after reconstitution in boiled water (Please read the manufacturer’s instruction for methods of dilution). Most people will find it more comfortable to rest the bowel for a few days by avoiding high fibre, high fat foods. Frequent ingestion of fruit drinks, non gassybeverages and soft easily digested foods ( eg. soups, crackers) are encouraged.

Routine use of antibiotics is not recommended as illness is self limiting. Antibiotics are indicated for those sufferers with high fever and prolonged diarrhoea. Antibiotics are indicated for diarrhoea due to invasive bacterial agents ( shigella, salmonella).

Anti diarrhoeal agents (such Loperamide ) works by decreasing the bowel contraction and may be used to decrease frequency of diarrhoea, liquidity of stool and abdominal cramps.   This drug should be discontinued and medical advice should be saught if illness does not improve after few days of therapy.

Avoidance of milk and milk products is recommended for the first few weeks to avoid worsening of the diarrhoea from lactase deficiency. Gastroenteritis can reduce concentration of the enzyme lactase and thus the ability of small bowel to digest lactose containing food.


What is the course of disease?

Illness is usually self limiting and lasts for 3 to 4 days. If diarrhoea is prolonged for more than three days, you are advised to visit your doctor for assessment and to obtain a course of antibiotics.


Can gastroenteritis lead to any serious sequelae?

Most people recover from an attack of gastroenteritis without any complication. In a minority of patients who fail to keep up with the loss of water in their stool, their body may become too dry and this can result in kidney failure.


When should I seek for medical opinion or hospitalisation?

Medical opinion should be sought in the following circumstances :

  • if diarrhoea persist for more than one week despite adequate self medication with hydration and anti diarrhoeal agents.
  • if you have just returned from area endemic with cholera ( especially if your diarrhoea is profuse and watery).
  • if you fail to keep your body hydrated with oral rehydration solutions due to severe vomiting. This means your doctor may need to give you intravenous fluids for a few days. The very young and old persons are particularly at risk to develop kidney failure in this situation.
  • if your stool shows blood and pus.
  • if you have high running fever.


What investigations would my doctors order?

Your doctor may order stool specimens for culture, blood test to check for white counts and severity of dehydration.


What should I do prevent getting gastroenteritis?

Prevention lies in the adherence to standard food handling techniques i.e. proper heating and refrigeration).


Diarrhoeal illness in special circumstances

I) Traveler’s diarrhoea

High risk areas for traveller’s diarrhoea are in developing areas of the world. Developed nations such as the United States, Europe, Australia pose the lowest risk. Travellers from low risk industrialised countries to high risk areas are at particular risk of getting traveller’s diarrhoea.

Illness is usually self limiting and lasts for three to four days if left untreated. Mortality from the illness is almost nonexistent but morbidity can be considerable, confining travellers to bed and disrupting their itineraries.

Escherichae coli (E. coli) is a common cause of traveler’s diarrhoea accounting for up to 70% of cases. Infection of these pathogenic agents is through ingestion of contaminated food or water.


What can I do to prevent getting traveller’s diarrhoea?

Raw vegetables, raw meat or seafood, and other moist foods maintained at room temperature are high risk items. Tap water and ice are also considered to be unsafe. In general, food consumed should be served piping hot.   Risk for development of travellers’s diarrhoea increases with eating food purchases from street vendors. Safe food items include boiled or bottled water and beverages, canned products, and fruits that can be peeled.

Studies have shown that prophylactic antibiotics are effective in reducing the frequency of traveller’s diarrhoea but this is generally not recommended due to side effects inherent with antibiotics consumption.


How should I treat myself?

  • Oral fluid is the mainstay of therapy.
  • If symptoms is moderately severe ( stools frequency of up to 5x per day), anti diarrhoeal agents such as loperamide ( Lomotil) at 4mg three times per day is recommended.
  • Medical opinion should be saught and antibiotics is recommended if frequency of diarrhoea is more than 6 times per day especially if there is associated fever or blood in the stools.


II) Cholera

Cholera is caused by the bacteria Vibrio cholera. It is endemic in southern Asia, Africa and Latin America where overcrowding with poor water and waste sanitation. Faecally contaminated water and seafood are the major vehicle of transmission for cholera.     Illness is caused by the bacterial toxin which induces the small bowel mucosa from an ‘active absorber’ of water to a ‘secretor’ of water. Illness varies from one of mild gastroenteritis to a severe profuse watery diarrhoea.   Faecal material has been described as of ‘rice water’ consistency. Up to one litre of water per hour can be lost during the illness. Diagnosis is made by isolation of the organism from stool. The main line of treatment is rehydration through oral or intravenous routes. Antibiotic is generally given as it shortens the duration of illness.


III) Antibiotic associated diarrhoea

Diarrhoea may occur during or after a course of antibiotics; there is usually no obvious pathogen. Symptom usually resolve after the completion of antibiotics. The course is benign and does not require any therapy.

However, the severe end of antibiotic associated diarrhoea is a condition called pseudo-membrainous colitis. This is so called because there is inflammation of the large bowel with a layer of mucus overlying the surface. There is suppression of the usual ‘resident’ bacteria which keeps the large bowel in healthy condition by the antibiotics with subsequent overgrowth of ‘harmful’ bacteria Clostridioides difficile (previously called Clostridium difficile).   This bacteria secretes a toxin which causes inflammation to the large bowel.   In addition to diarrhoea, there is also passage of blood and mucus in stool. If you have onset of diarrhoea after a recent course of antibiotic and the stool is bloody, you should visit your doctor to get the appropriate therapy.


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