About 8-9 litres of fluid enters the gastrointestinal tract. This consists of a dietary intake of 2-2-½ litres and the rest is made up of various digestive secretions like saliva, gastric juices, bile, pancreatic and intestinal secretions. Normally, most of it is reabsorbed in the small intestine and only a litre reaches the large intestine (colon), which further absorbs some water and salts and finally only about 100-300 gm of this is passed out as faeces. The volume of faeces is more in our population because of the high fibre intake. It is much lower in the western non-residual diet. Diarrhoea occurs due to the presence of a poorly absorbable substance in the lumen of the intestine (osmotic diarrhoea) or some defect in the cells lining the intestine, resulting in pouring out of the fluids (secretory diarrhoea) or actual inflammation of small or large intestines (exudative diarrhoea).

Various descriptive names are used for different kinds of diarrhoeas. Acute explosive watery diarrhoea often accompanied by vomiting is referred to as acute gastroenteritis and is perhaps the commonest cause of infective acute diarrhoea. There is no accompanying blood or mucus in the stools. It consists of large amounts of frothy, thin yellowish green fluid. It is caused by various bacterial, viral and parasitic infections. The toxins produced by these organisms may be already formed in the food before it is consumed or it may be produced after they enter the gastrointestinal track.

Cholera is a specific form of acute diarrhoeal illness caused by a form of bacteria, vibrio cholerae, which has played havoc in the gangetic delta of West Bengal and Bangladesh. It has been responsible for huge epidemics spreading across West Asia, Africa, Europe and even up to the USA. With the rapid migration of population across the Indian continent as well as other parts of the world, cholera is no more limited to its original geographical limits. In fact, from time to time cholera cases have been reported in and around Chandigarh, where there is a large migrant population. Stools in cases of cholera are described as ‘rice watery’ because of mucus flakes and a large number of cells floating in the watery stool. The water loss is devastating and a person can die in a few hours. Some of the readers would recall the havoc it played among the refugees during the 1971 Bangladesh war.

Acute infective diarrhoea may take the form of dysentry which is characterised by frequent but relatively small volume of stools containing blood and mucus, accompanied by cramps and signs of inflammation like fever and toxaemia. The best known examples of dysentry are amoebic dysentry caused by amoeba and a group of bacteria discovered by Japanese bacteriologist Shiga in 1897 and referred to as shigellosis.

Although diarrhoea is not the main feature in typhoid fever but in its basic epidemiology and causation, typhoid fever is very akin to this group of diseases with the difference that the bacteria causing typhoid (salmonella typhi) lodges itself in the wall of the intestine and enters the blood, causing severe toxicemia and high fever.

Traveller’s diarrhoea is one of the very common diarrhoeal illnesses. It was referred to by various colourful names like ‘hill diarrhoea of Shimla,’ ‘Mexican belley’ and I am tempted to coin another name, the ‘Shatabadi Express tummy’ considering the number of people who develop this ailment after travelling on the train. The cause of traveller’s diarrhoea is unclean water and food during travel, specially in the tropical parts of the world, including South East Asia, Mexico and African countries.

Although any form of bacterial, viral or parasitic infection can be responsible for traveller’s diarrhoea, depending upon the prevalence of an organism in the area of travel, but a bacteria, e.coli, has now been found to be the commonest cause of this type of diarrhoea. This bacteria is a normal habitant of the intestine but certain strains of this can cause devastating diarrhoea.

The secret of management of infective diarrhoea lies in prevention by good public health measures, supply of clean drinking water and health education among the masses. It cannot be overemphasised that a lot of responsibility lies with the village panchayats, municipalities, public health departments of the state and the Central Governments to make every effort for the provision of safe drinking water.

• At the personal and family levels. water can be filtered, boiled or exposed to sophisticated equipment using ultravoilet rays.

• Food handlers in all hospitals, restaurants and caterers should be closely screened and supervised.

• Cut fruits, unwashed fruits, vegetables, salads and articles containing green leaves are better avoided.

• In hot weather, leftover foods should be avoided and no stored in the refrigerator for more than 6-8 hours as bacteria do start growing after some time.

• While travelling one should take precautions and avoid exposed raw fruits, cold snacks of any kind, unbottled drinks and any thing does not appear to be clean. Even bottled mineral water has been found to be unsafe in Chandigarh itself as the plants preparing it do not meet the standards.In case of children extra precaution is required. It is much safer to breast feed the child for at least 6-9 months and feed with simple spoon, cup or glass later.

• Washing hands before eating anything and keeping the eating area clean are a must.

• The Public Health Department should carry out frequent checks at all levels of public catering, including rehri markets or dhabas.

• For travelling into the endemic areas, cholera vaccine and other available vaccines should be used for prevention.

• Since diarrhoeal diseases can kill by loss of water and salt, even before reaching a doctor or hospital, salt and fluid should be replaced with oral rehydration salts (ORS). These can be prepared by putting a little sugar, salt and baking soda in boiled water. Rice water and coconut water are other simple substitutes which can prevent initial dehydration.