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Diarrhoeal diseases
Slum area in central Antanarivo, Madagascar.
Credit: WaterAid / Jeremy Horner
Diarrhoea itself is not a disease, rather it is a symptom of many diseases.
Diseases that cause diarrhoea are the most deadly, killing over two million people every year - mostly children under the age of five.
There are approximately four billion cases of diarrhoea each year which are caused by more than 100 different bacteria, protozoa or viruses.
These are spread through:
Contaminated water
Contaminated food
Unsanitary disposal of human waste
Poor personal hygiene
Diarrhoea causes the rapid depletion of water and sodium in the sufferer. If these are not replaced quickly, the body starts to become dehydrated and the body's salt balance is severely damaged.
If more than 10% of the body's fluid is lost the sufferer dies. Children who are malnourished suffer the most, becoming even weaker and more malnourished as diarrhoea progresses.
Types of diarrhoea
50% of deaths from diarrhoea are from acute watery diarrhoea where the sufferer cannot be rehydrated
35% are through persistent diarrhoea (lasting 14 days or longer)
15% of deaths are through dysentery (or bloody diarrhoea)
The three most deadly diarrhoeal diseases are cholera, bacillary dysentery and typhoid. Others include amoebic dysentry, giardiadis, salmonella, camplyobacteriosis and cryptosporidiosis.
All of these diseases can be stopped by the same preventative methods, so if the three most deadly were eliminated the others would be too.
Cholera is a disease that can cause large epidemics killing the young, the weak and the old. It is known and feared throughout the developing world. The bacteria, which can last for up to three weeks in soil, is spread by contaminated water, food and occasionally by person to person contact.
Sudden large outbreaks are usually caused by a contaminated water supply.
Effect on health: The bacteria attaches to the wall of the small intestine where it multiplies and produces a poisonous chemical. This poison prevents the body from taking water from the intestine and so the body rapidly dehydrates.
Up to 14 litres of diarrhoea can by passed in one day. The lack of water in the body causes the blood pressure to drop and the kidneys to fail. Death occurs within 24 hours.
Bacillary dysentery is more severe than amoebic dysentery. It is estimated that 140 million people are infected each year resulting in around 300,000 deaths annually, mostly among children under the age of five.
It is caused by Shigella bacteria which enter the body through contaminated drinking water, food or flies which then infect the large intestine. It can be spread between people - especially young children.
Effect on health: Symptoms can include fever, abdominal pain, nausea, cramping and severe, frequent, watery diarrhoea that can contain blood, mucus and pus.
Typhoid fever affects 17 million people worldwide every year, with approximately 600,000 deaths. It is contracted when people drink water or eat food infected with a bacterium called Salmonella Typhi found in human waste.
It has been virtually eliminated in the western world through sanitary facilities.
Effect on health: Typhoid fever is recognised by the sudden onset of sustained fever, severe headache, nausea and constipation. Later it is accompanied by diarrhoea, a rash and other complications which can include intestinal haemorrhaging or perforation.
Giardia normally produces a mild bowel infection, with symptoms of nausea, vomiting, diarrhoea, malaise, and poor appetite, its effects can be much worse in developing countries. Where people have nutrient-poor diets it can become chronic, suppressing adequate calorie intake and leading to weight loss, and in some cases death.
Rotavirus causes severe diarrhoea and vomiting and is estimated to kill around 600,000 children under five every year in developing countries. It is highly infectious and spreads when children are exposed to contaminated water, food or faecal matter.
Prevention of diarrhoeal diseases
Robert Chusale from Malawi, drinks safe water from a WaterAid pump.
Credit: WaterAid / Jon Spaull
Diarrhoeal diseases can be prevented by improving access to clean water and sanitation so that bacteria cannot re-enter water supplies. Hygiene education plays a vital role in informing communities about safe hygiene.
The keys to prevention are clean water, clean hands at meal times and uncontaminated food.
Hygiene education where communities learn about the benefits of using latrines, keeping food and water clean, cooking food thoroughly, washing and peeling fruit and vegetables, washing hands with soap before touching food and the sanitary disposal of human waste can all help prevent diarrhoea and contamination.
Life on the edge
Honufa was interviewed in a tiny room with ten women and a health worker from the Outfall Slum in Dhaka, Bangladesh.
When asked if anyone knew of someone whose child has died, three out of the ten women put their hands up. But it wasn't from second hand experience - each of these women had lost a child due to poor sanitation and unclean water.
"Life is very hard here." Honufa says. "You can see the condition of the houses all crammed together. There is no space and you can imagine the unhealthy situation we live in. We have tubewells but the surrounding area is full of rubbish and the sanitation conditions everywhere are foul.
Every day there is disease in this slum. There is diarrhoea, dysentery, severe stomach pains and headaches. Children suffer the most. I've lost a two year old son from diarrhoeal diseases. We need a clean environment here."
Honufa is now part of a group working with WaterAid's partner, PSTC to learn about safe hygiene, water and sanitation.
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