1. Introduction

Cholera has spread widely since 1961 and now affects at least 98 countries. Extensive experience has shown that the introduction of cholera into a country cannot be prevented; its spread within a country, however, can be contained by appropriate control measures.

During the past three decades, intensive research has contributed substantially to our understanding of the epidemiology and clinical management of cholera. It is now known that:

· in more than 90% of cases cholera is mild, and may therefore be difficult to distinguish from other types of acute diarrhoeal disease;

· asymptomatic carriers of the disease are common;

· improved treatment, in most cases by oral rehydration therapy, can reduce case fatality rates for cholera to less than 1%;

· where cholera is present but not epidemic, it causes fewer than 5% of all cases of acute diarrhoea;

· vaccination, mass chemoprophylaxis, and cordon sanitaire are ineffective in preventing or controlling outbreaks;

· care in drinking and eating habits, safe disposal of excreta, and personal cleanliness are the most effective ways for individuals to reduce the risk of cholera.

Because cholera can be an acute public health problem, with the potential to spread quickly and cause many deaths, special attention must be given to surveillance and control. These guidelines provide information to assist national diarrhoea control programmes, emergency task forces, and others in their efforts to control cholera.