Introduction and Classification of Childhood Diarrhoea

1.1 Diarrhoea is a global problem Diarrhoea is one of the most common causes of morbidity and mortality in children worldwide. The word diarrhoea is derived from the Greek "diarrhoia", meaning to flow through. In clinical terms, diarrhoea refers to either an increased stool frequency or a decreased stool consistency, typically a watery quality. The World Health Organization (WHO) defines a case as the passage of three or more loose or watery stools per day. Nevertheless, absolute limits of normalcy are difficult to define; any deviation from the child's usual pattern should arouse some concern (particularly when the passage of blood or mucus, or dehydration occurs) regardless of the actual number of stools or their water content. Diarrhoeal illness is the second leading cause of child mortality; among children younger than 5 years, it causes 1.5 to 2 million deaths annually. In 1982, on the basis of a review of active surveillance data from studies conducted in the 1950s, 1960s and 1970s, it was estimated that 4.6 million children died annually from diarrhoea. In 1992, a review of studies conducted in the 1980s suggested that diarrhoeal mortality had declined to approximately 3.3 million annually. It was noted that children in the developing world experienced a median of between two and three episodes of diarrhoea every year. Where episodes are frequent, young children may spend more than 15% of their days with diarrhoea. About 80% of deaths due o diarrhoea occur in the first two years of life. The main cause of morbidity from acute diarrhoea is dehydration, which results from loss of fluid and electrolytes in the diarrhoeal stools. In severe cases this could lead to vascular collapse, shock and eventually death. Other causes of death include malnutrition from loss of nutrients from the stool, effects of infection on metabolism and the withholding or modification of food during diarrhoea which is a common practice. Diarrhoeal illnesses may have a significant impact on psychomotor and cognitive development in young children. Early and repeated episodes of childhood diarrhoea during periods of critical development, especially when associated with malnutrition, co-infections, and anemia may have long-term effects on linear growth, as well as on physical and cognitive functions. Worldwide childhood death secondary to diarrhoea declined from an estimated five million per year in 1980 to less than two million in 1999. The decline is generally attributed to global