The treatment of most cases of diarrhoea is essentially the treatment of dehydration and electrolyte disturbances - replacing the fluid and salts being lost. In global terms, ORS is arguably the most important medical discovery since penicillin.

Diarrhoeal diseases have long been recognised as leading causes of global illness and death and are the commonest cause of deaths among children. Medical estimates have calculated that diarrhoea will claim 92 million lives by 2025. During protracted war and conflict in particular, simple diarrhoeal diseases can often kill more people than the fighting itself, as communities are dislodged and existing healthcare services are thrown into chaos. Many of these deaths, which disproportionately affect those living in the developing world, are largely preventable.

Coma and death

Diarrhoea can be a result of infection from a variety of micro-organisms and causes a person to lose both water and electrolytes, leading to dehydration and electrolyte disturbances. As severity increases, internal organs start to fail, and the patient may go into a coma. Death from dehydration usually occurs when 10-15% of the total body weight is lost. In severe diarrhoea, such as that caused by cholera, this may take only a couple of hours. Nutritional status is often an important determinant of death. In children with vitamin A deficiency, for example, the risk of dying from a diarrhoeal disease increases by more than a fifth. Patients with AIDS are more susceptible to diarrhoeal illness and have a higher case fatality rate than those without AIDS.

Recognising potential

Médecins Sans Frontières is an independent emergency medical relief organisation that is currently responding to emergencies in more than 80 countries around the world. Because an epidemic of diarrhoeal disease is always a risk in an emergency situation, the charity ensures that its teams in the field are trained to respond. Refugees are often crowded together in conditions of poor hygiene and sanitation, and many cases of diarrhoea almost always occur. If cholera breaks out, for example, it may spread extremely fast. The key is for medical staff to be able to detect a potential epidemic and to be able to offer treatment quickly.

Managing outbreak

To manage an outbreak of diarrhoea effectively, humanitarian organisations must set up a sound system of logistics. Teams generally assume that they will have to deal with large numbers of dehydrated people and prepare themselves accordingly.

Each sachet contains a mixture of glucose and electrolytes (including sodium and potassium), and must be mixed with a litre of water. In global terms, ORS is arguably the most important medical discovery since penicillin. However, many patients, especially those with cholera, vomit so profusely that they cannot drink. These patients are therefore given intravenous fluids. Some patients who are losing fluids rapidly need a drip in each arm.

The challenge for a doctor or nurse is to find a vein in a profoundly dehydrated patient; as a patient loses fluid their veins collapse. Patients with cholera or Shigella dysentery are usually given antibiotics to shorten the period of severe diarrhoea and improve their outcome. Treating serious cases requires a high degree of skill and experience. In most cholera outbreaks, teams are able to limit the case fatality rate to less than 1%.

Access to water

Inadequate availability of water for hygiene, lack of access to safe water, and consequent ingestion of dirty water are estimated to contribute to around 88% of deaths from diarrhoea globally. A billion people lack a basic water supply, prompting the United Nations last year to add unfettered access to clean water to its international covenant on economic, social, and cultural rights.

BIOFOTO ASSOCIATES/SPL Adenovirus: another cause of diarrhoea

Stopping the spread

Because no vaccines are effective against any of the organisms that cause diarrhoea, the only way to prevent its spread is to interrupt the faecal-oral cycle of contagion. This is done by providing health information about washing hands, disposing of faeces, and protecting household water stocks.

The logistical experts at Médecins Sans Frontières work with the community to ensure they have pit latrines - the minimum number required in an emergency situation is one for every 20 people - and adequate supplies of safe water, of which a person needs a minimum of 10 litres each day.

Although basic guidelines and minimum standards for detecting and responding to epidemics of diarrhoea are well developed, the realities facing teams of doctors, nurses, and logisticians in an acute emergency are rarely so straightforward.

Delivering high quality health care in such a context is often chaotic and difficult and poses considerable personal risk to medical staff. Working as a team is vital, and those involved must be prepared to think on their feet and work around the clock. Often the sheer numbers of patients involved can be overwhelming.

Conflict and displacement

In many acute emergencies, just gaining access to people affected and ensuring a humanitarian space in which to provide treatment is often hard, sometimes impossible. In recent fighting in the eastern part of the Democratic Republic of Congo, for example, hundreds of people fled towns and villages into the surrounding bush, where they spent many weeks without any access to healthcare facilities at all.

Teams could not get access to those most at risk outside of the cities because of the heavy military presence in the region and ongoing insecurity. Similarly, in Liberia earlier this year, when conflict restarted in the capital, Monrovia, street fighting led to daily population movement in addition to the thousands of displaced people arriving in the capital.

Although a total of 11,492 suspected cases of cholera were reported from January to August 2003, teams had evidence that this was just the tip of the iceberg and that people were not accessing healthcare facilities because of the fighting and insecurity.

Epidemiological surveillance

The priorities for health agencies in emergency settings are to remain vigilant and reactive to epidemics of diarrhoeal diseases in emergency settings. Good epidemiological surveillance is crucial to this process, as well as improving water supplies and sanitation facilities to prevent the spread of infection.

Ensuring that humanitarian workers have a space in which to work and that affected populations have access to available treatment is vital if case fatality rates from these basic treatable diseases are to be kept to a minimum.

Unfortunately, diarrhoea is a killer in so many settings. Poverty and ignorance of basic hygiene rather than conflict are likely to be the causes.