**1. Introduction**

Acute diarrhoea is defined as frequent passage of loose or watery stools mixed with mucus and causes morbidity and mortality particularly in children. The scope of the book is to present information on acute diarrhoeal diseases in relation to clinical features, dehydration, management and prevention. When the stool contains blood, it is called dysentery. Acute diarrhoea is an ancient problem with tremendous public health significance. Acute diarrhoeal diseases comprise of acute watery diarrhoea and acute bloody diarrhoea (dysentery). The prototype of acute watery diarrhoea is cholera, while the same for dysentery is shigellosis. It caused extensive epidemics during flood, famine, war and earthquake when large number of people is shifted to refugee camps.

## **2. Disease burden**

According to an estimate [1] by the World Health Organization, 3–5 million cholera and cholera-like cases occur worldwide, and 100,000–120,000 million cases die with a case-fatality rate of 2.25% (range 1–10%). This figure is actually grossly underestimated, because of under-reporting. These diseases, under the overarching syndrome of acute diarrhoea, cause tremendous pressure on the healthcare delivery system, and during epidemics and pandemics, this is compounded as a real public health problem. There have been seven pandemics (epidemic all over the world) of cholera which spread to more than 102 countries worldwide and killed millions of people.
