Everybody at some point in their life has suffered from diarrhoea. For most of us it is nothing more than an unpleasant and inconvenient short-lived affliction. However, diarrhoea is one of the top causes of mortality in under-5's in the world, infact, for the period 1995-2000 it was the top cause of infant mortality.

Diarrhoea is the result of fluid and electrolyte loss into the lumen of the gut leading to the production of unformed or liquid faeces. It is most frequently caused by infection of the intestine by a pathogen (bacterial, viral or protozoan) but it can also becaused by toxins (such as those secreted by some bacteria) or chemicals (phenolphthalein produces extremely violent and copious diarrhoea). Diarrhoea can be thought of as the mechanism by which the intestine purges itself of an irritant or pathogen.

Most cases of diarrhoeal disease go undiagnosed either because they are short-lived and self-limiting and the patient doesn't seek medical attention or because medical and laboratory facilities are not available.

In warmer climates diarrhoea becomes a more serious problem. Fluid and electrolyte loss can be severe and acute dehydration is a real possibility, children are particularly susceptible . Without adequate rehydration and electrolyte-replacement death can follow rapidly.

Infectious Causes of Diarrhoea

A) Food poisoning - toxins in food

B) Intestinal infections

Determination of the pathogen responsible for diarrhoea is almost impossible clinically. However, gathering information on the patient's food intake and recent travel history in addition to macroscopic and microscopic examination of the faeces can provide an indication of the likely cause. A precise diagnosis can only be obtained through laboratory investigation.

Medical Microbiology. Mims et al. Mosby 1994
Unicef (www.unicef.org)