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what's Dirty, Wet And Dangerous

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WATER [image, unknown] Guide to water-related diseases

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What's dirty, wet and dangerous?
The World Health Organisation estimates that 80 per cent of all sickness and disease can be attributed to inadequate water and sanitation. Such diseases cause an estimated 25 million deaths each year. And children are hardest hit: one child in seven in the developing world dies before its fifth birthday. Most of these deaths could have been prevented.

'CLEAN WATER and sanitation for all by 1980' - this is the aim of the UN Drinking Water Supply and Sanitation Decade. And there is little doubt that many thousands of wells will be drilled and pit latrines dug in the next ten years. All in the quest for health. But unless improved water supply and sanitation really do lead to improved health the estimated $80 million per day needed to fulfil the Decade's targets might as well be dropped into one of its spanking new latrines.

Yet studies of the effect of water supplies and sanitation facilities on health have been disappointing, usually there is very little effect. Life - and death - go on more or less as before, with or without the shiny row of taps in the village clearing, with or without the neat concrete footprints either side of the latrine hole.

To find out why, the Ross Institute of Tropical Hygiene in London has devised the 5-way cause-and-prevention classification of water and sanitation related diseases shown below.

This classification focuses on the ways such diseases are transmitted as well as pointing to appropriate methods of preventing their spread. And it can help to explain and predict the effects of any new water or sanitation facility on the health of the community.

Imagine a village recently provided with a convenient, clean water supply. Women need no longer carry heavy pots of polluted water from the local lake. But without health education they will not use clean water any differently from dirty water. So only diseases caused directly by faeces polluting drinking water (some in the faecal/oral group in the table below) will be affected by the new water supply. Hygiene, sanitation and water storage habits will remain unchanged unless people learn how to protect their health, have access to facilities that help them and believe that the health benefits are worth the inconvenience of changing their most personal of habits.

[image, unknown] HAND TO MOUTH
(Faecal-oral diseases)
Sick person transmits diseases in faeces. Worm eggs, amoebic cysts, viruses or bacteria pass into drinking water or onto hands and food to be eaten or drunk by uninfected people. Prevent by scrupulous use of latrines, washing hands after defecation, drinking clean water, and covering food to discourage flies. Special attention should be paid to infant sanitation and hygiene.
Amoebic dysentry
Severe diarrhoea with mucus and blood caused by tiny animal called amoeba. Spread by faeces on hands or in water. 400 million causes cause 30,000 deaths each year.
Polio (poliomyelitis)
Acute disease spread by virus in faeces. Can affect brain and spinal cord to cause paralysis and muscle wasting. 80 million cases cause up to 20,000 deaths and many disabilities yearly, mainly in children under two.
Roundworm (ascariasis)
Eggs pass out in human faeces, thence to uninfected person's mouth. Tiny worms migrate through body to the intestine where they grow into 20-30 cm adult worms. In some villages over 60 per cent of people are infected.
[image, unknown] SKIN TO SKIN
(Water-washed diseases) Unwashed skin and clothes encourage disease. Transmission is by touching infected person or by flies. Prevent by frequent washing in lots of water.
Virus infection of outer parts of eye eventually causing build up of scar tissue over eye and blindness if untreated. Spread by flies and touch. 500 million people infected world-wide, especially in arid areas.
[image, unknown] WALKING IN THE WATER
(Water-based diseases)
Disease passes from faeces, urine or skin or sick person into water-dwelling animal such as snail. Spread to uninfected person is when s/he walks in water (bilharzia), drinks the water (guinea worm) or eats infected fish (Chinese liver fluke). Prevent by using latrines, reduced contact with infested water, control of snails, cooking fish thoroughly.
Guinea worm
Tiny crustaceans called cyclops containing immature guinea worms taken into human body with drinking water. Worms grow to 70-100 cm before breaking through skin on victim's legs or feet. When victim stands in water, baby worms pass from wound to water and back to cyclops. Five per cent of the 500 million cases each year became permanently disabled.
[image, unknown] BITTEN BY THE WATER
(Water-related insect vectors)
Infection passes into insect when it bites sick person. Infected insect then transmits disease by biting uninfected person. Such insects mainly found near water where they breed. Prevent by covering wells, destroying breeding sites where possible; control of insects.
River blindness (onchocerciasis)
Infection is caused by minute worms carried from person to person when bitten by small black flies that breed in fast flowing water. Worms spread inside body often to eyes where damage and scarring eventually causes blindness. Worst affected area is the Volta River basin where about one million people are infected and 70,000 are blinded.
[image, unknown] STEPPING INTO DANGER
(Faecal-disposal diseases)
Mainly transmitted when uninfected person steps with bare feet in faeces of infected person. Prevent by using latrines, burying faeces, wearing shoes.
Eggs in faeces of infected person hatch and enter bare feet of uninfected person, pass to lungs, are coughed up and swallowed then pass to gut. Adult worms can cause severe bleeding and anaemia. In some villages half the population is infected.

Photo: Claude Sauvegeot
Photo: Claude Sauvegeot
Photo: Camera Press/Claude Jacoby
Photo: Camera Press/Claude Jacoby

Diarrhoea is a major cause of death in under-five year olds throughout the world. It directly kills six million children in developing countries each year and contributes to the death of up to 18 million people. Victims often die of dehydration caused by fluid loss from the body into the intestine and out in the liquid faeces. Survivors are weakened and easy prey to other diseases. In unsanitary conditions the disease easily passes from child to child. The cure is rehydration: replacement of lost fluid and salts by weak sugar and salt solution taken either by mouth or intravenous drip. The short circuit of diarrhoea-dehydration-death is rapid and tragic, particularly when cure is so simple.

Bilharzia (schistosomiasis)
200 million infections world-wide cause untold misery and debility in Africa, the Middle East, parts of Latin America and South-East Asia. Victims become weak and less able to work - causing an economic loss, excluding treatment costs, estimated at over $200 million in Africa alone. Ironically the disease is often made worse by dams and irrigation schemes. The quiet, weedy canals and lakes are ideal breeding sites for snails. China led the way in bilharzia control by enforcing sanitary habits and mobilising communities to clear canals of weeds and snails.

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Each year 800 million people shake and moan with the fevers of malaria. And it kills up to one million children under two in sub-Saharan Africa alone. Common in many of the hot, tropical parts of the world, malaria is carried from person to person when they are bitten by carrier mosquitoes. Almost any amount of water - from lakes to tin cans, drinking pots and shallow puddles - is sufficient for mosquitoes to lay their eggs. Prevent, by controlling the mosquitoes and mass drug treatment of infected populations. But both tasks, are getting more difficult as mosquitoes become I resistant to insecticides and malaria parasites become resistant to drugs. Malaria is now on the increase in many countries.


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New Internationalist issue 103 magazine cover This article is from the September 1981 issue of New Internationalist.
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