Diarrhoea in the tropics

Diarrhoea is very common in the tropics. It is often self-limiting, but its general significance cannot be overestimated. It is a major cause of malnutrition and is one of the main causes of death, particularly in children. What precisely is meant by diarrhoea varies between patients. An increased number of bowel movements per day, a looser consistency of the faeces or an increased volume of stools all are used to define the problem. The WHO definition of diarrhoea is at least 3 evacuations every 24 hours of unformed faeces (they take the shape of any container into which they are evacuated). WHO emphasises the importance of change in stool consistency rather than frequency, and the usefulness of parental insight in deciding whether children have diarrhoea or not.

Diarrhoea causes fluid loss resulting in dehydration. The patient also looses electrolytes, which can lead to ion imbalances, such as hypokalaemia. Acidosis develops due to the loss of bicarbonate in the stools, to reduced renal function (less acids are excreted) and to ketosis (breakdown of body fat due to reduced food intake). Often the patient has no appetite and the nutritional status which is sometimes already poor deteriorates further. Sometimes the mother thinks she is doing good by “letting the intestines rest” and temporarily not giving food. Moderate undernourishment can then develop into severe malnutrition (marasmus and kwashiorkor). The latter is often seen if a patient has had a number of episodes of diarrhoea in quick succession.

Dysentery is a severe form of diarrhoea. Fever is common in bacillary dysentery, but rare in amoebic dysentery. Dysentery has three characteristics:

• Abdominal pain

• Tenesmus (pain due to cramps in the rectum) and false defecation need

• Frequent evacuation of small quantities of faeces that are mixed with blood, mucus and/or pus

Steatorrhoea or fatty diarrhoea is characterised by large quantities of faeces with an increased fat content (the stools float on water). This occurs in certain malabsorption syndromes. The cause usually lies in disorders of the pancreas or small intestine.

Category: Medical Subject Notes , Medicine Notes