Cholera definition and MSF treatment
1 January 2001
In 1817, a new and terrible disease moved out of Bengal and began to spread across the world. It caused profuse diarrhoea and vomiting, and its sufferers died of profound dehydration, sometimes within a matter of hours. By the end of the nineteenth century it had killed many hundreds of thousands of people across Asia and then Russia, Europe, and the Americas. Like many diseases it was given a Greek name... cholera. The word means diarrhoea. Now, at the end of the 20th Century, the world is being circled by the seventh great pandemic of cholera. More than 60 countries report outbreaks each year. MSF teams are currently battling the disease in places as diverse and as far-flung as Guinea in West Africa, Guatemala and Peru in Latin America, and Bangladesh in southern Asia. How cholera kills The germ Vibrio cholerae is excreted by a sufferer in the stools and vomit. It can then be spread directly to other people if they touch the patient and then fail to wash their hands before eating. The germ can also contaminate food or water supplies. In the latter case this will cause an explosive outbreak because many people will ingest the vibrion in a short space of time. Once inside the intestine, the cholera vibrion multiplies and produces a toxin. This toxin causes the cells lining the intestine to secrete massive volumes of fluid... leading to the characteristic diarrhoea and vomiting. The diarrhoea is odourless and looks like rice water. A patient under treatment can lose more than 50 litres of fluid during a bout of cholera. A person who is not treated will die of dehydration well before this. In fact death usually occurs when 10 to 15 per cent of the total body weight is lost. In severe cases this may take only a couple of hours. Logistics of managing a cholera epidemic During a new influx of refugees the people are often crowded together in conditions of and poor hygiene and sanitation. If cholera does break out it may spread like wildfire, and eventually affect up to 5 per cent of the population. That may not sound many but in a refugee population of 100,000 persons that means 5,000 cases which may all occur over a matter of days or weeks. The only way to cope with such a large number of cholera patients is to have highly effective logistics. The logistics of an MSF response to cholera includes the following elements:
having trained field volunteers on standby for rapid deployment use MSF cholera kits that contain all the equipment and supplies that a team needs in order to be able to start work immediately. prepositioning of kits and supplies in a cholera-prone region building cholera treatment centres according to a tested MSF design to centralise staff-intensive activities such as IV rehydration setting up decentralised oral rehydration corners for treating mild cases in the community
training community health workers to identify new cases and bring them in for treatment
setting up adequate water supplies and sanitation facilities to limit contagion.
There is at present no effective vaccine against cholera. The only way to prevent its spread is to interrupt the faecal-oral cycle of contagion. The ways MSF teams do this include:
providing health education to a population on how to prevent diarrhoeal disease. The messages include hand-washing, disposal of faeces and protection of household water stocks. provision of soap to refugees.
working with the community to ensure they have pit latrines. The minimum number required in an emergency situation is 1 latrine per 20 head of population.
setting up adequate supplies of safe water. The minimum quantity required in an emergency population is 10 litres per person per day.
In all of these preventive activities MSF water and sanitation engineers and logisticians have a vital role to play - just as important as the role of doctors and nurses.
During the floods in Bangladesh in 1998, many thousands of water wells across the country became contaminated by the rising waters. Cholera vibrios were washed down the pump shafts into the water table below. The greatest danger came after the flood waters started to recede, when people went home and began using their wells again. Part of the health education given by MSF teams to villagers was instruction on how to disinfect their wells:
An example - Protecting water supplies from cholera
unbolt the cover plate from the pump casing, and remove the pump handle.
pour a few hundred grams of bleach powder down the shaft. The bleach releases chlorine, which is a strong disinfectant, capable of killing cholera vibrios.
re-assemble the pump.
allow the bleach to stay there for 12 hours.
then pump water from the well for an hour, allowing it to drain away. After that your water will be safe to drink.
How MSF teams treat cholera patients
Cholera is eminently treatable. The main pathological process it causes is dehydration - thus the treatment we use is simply to replace all the fluid being lost.
MSF treats many patients using oral rehydration solution, called ORS. This is a mixture of glucose and electrolytes (such as sodium and potassium) that comes in sachets. Each sachet is stirred into a litre of water and provides the correct balance of electrolytes to rehydrate a cholera patient. It has been said that in global terms ORS is the most important medical discovery since penicillin.
However many of our cholera patients vomit so profusely that they cannot drink ORS. MSF therefore treats serious cases by putting in intravenous drips. These IV infusions contain fluid and electrolytes. Some patients lose fluid so quickly that they need two drips, one in each arm. The challenge for an MSF doctor or nurse is to find a vein in a profoundly dehydrated patient - for as the patient loses fluid their veins collapse. Treating serious cases requires a high degree of skill and experience. In most situations MSF teams are able to limit the case fatality rate to less than 1 per cent.