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The 25th of April is World Malaria Day, raising awareness of the fact that although malaria is preventable and treatable, it is the world's second largest killer, causing up to three million deaths per year — one death every 30 seconds.

By providing clean water stored underground, sand dams can help prevent the spread of malaria. An incredible 85–90% of malaria fatalities occur in sub-Saharan Africa and the vast majority of those deaths are of children under five years old. In Kenya as a whole, nearly 30% of deaths of under five year olds are attributable to malaria. Sadly, efforts to reduce the prevalence of the disease appear to have had little impact since 1992, despite the sixth Millennium Development Goal being to halt and begin to reverse the incidence of malaria by 2015.

It is not unreasonable then that the World Malaria Day partnership describes this disease as a ‘scourge that is preventable’. Apart from the obvious cost in human lives, malaria impacts a country’s ability to grow economically. The economic cost to the whole of Africa of this ‘scourge’ malaria has been estimated at US$ 12 billion a year.

In the areas where Excellent Development works, malaria is endemic. Those children who survive their early years gain some immunity to the disease, although when women later on become pregnant, their immunity can be impaired; infections at this time can lead to stillbirths and young infant mortality.

Malarial infection can be reduced by use of mosquito nets and insect repellents, or by draining standing water where mosquitoes lay their eggs. Not all of the farmers we work with will be able to afford the first two, but they can address the third. Building sand dams to improve the supply of clean water is a very effective way of achieving this. Because sand dams store water below sand, pools of still water are avoided – people can access water but the mosquitoes cannot. In this way the water can be used to support economic development rather than being a source of disease which can hinder it.

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The parasite that causes malaria in humans breeds within and is transmitted by certain species of mosquito. The classic symptom of malaria is a cyclical occurrence of sudden coldness followed by rigor and then fever, vomiting and sweating lasting four to six hours, recurring every few days. Severe malaria can progress extremely rapidly and cause death within hours or days – clearly a crucial factor in rural areas far from health facilities.

The Infection Cycle:

A mosquito becomes infected when it takes a blood meal from an infected human. Once ingested, the parasite reproduces in the mosquito gut. The immature parasites then migrate to the mosquito’s salivary glands, where they are then ready to infect a new human host. The parasites are injected into the bloodstream, alongside saliva and anti-coagulants, when the mosquito takes a subsequent blood meal.

The parasites leave the mosquito, entering the human bloodstream and migrating to the liver, where they infect liver cells. Within the liver cells they multiply asexually, yielding thousands of new cells within a few days which, following the rupture of their host liver cells, escape into the blood stream and infect red blood cells.

Within the red blood cells the parasites multiply further, periodically breaking out to invade fresh red blood cells. Several such cycles occur, which correspond with the waves of fever experienced during the illness.


The Bite:

Only female mosquitoes bite animals to get blood needed to produce eggs. Since the normal mosquito diet consists of nectar and fruit juice, which has no protein, females must drink blood to enable egg development. The males do not transmit the disease, and their mouth parts are not suitable for blood-sucking. A female mosquito’s mouthparts, however, are highly serrated (as opposed to a syringe's typically smooth needle) leaving a minimal number of points of contact with the skin being pierced — this reduces nerve stimulation to the point where the mosquito "bite" is typically not felt at all.

The females prefer to feed at night. During the day they usually find somewhere cool to rest. They usually start searching for a meal at dusk, and will continue throughout the night until taking a meal. They locate their targets primarily through heat and scent. They are extremely sensitive to the carbon dioxide in exhaled breath, as well as several substances found in sweat. Repellents like DEET work by disorienting the mosquito as it gets close to its potential next meal but do not kill them.

Once they have eaten, the females lay their eggs in fresh or stagnant water. A mosquito may lay eggs every third night during its life span if it can find enough blood to develop the eggs. The larvae hatch after about 48 hours, living in the water and coming to the surface to breathe. Most larvae use siphon tubes going to the water surface for breathing, which is why they need the water to be still.

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How Can Sand Dams Help?

By creating a reservoir of clean water below ground level, sand dams do not create potential mosquito breeding sites, in comparison to open water dams. In addition, a secure water supply enables a greater range of foods to be grown. Improved diets and nutrition are good for health, and boost the immune system.

Furthermore, the increased water supply created by sand dams enable farmers to plant Neem trees, the leaves of which are brewed into tea, and make an effective cure for malaria. This is particularly relevant due to the difficulty in accessing ‘modern’ healthcare: around 80% of people in rural Africa depend on traditional medicine for their primary health care, which is one of the reasons why Excellent Development supports farmers in growing medicinal trees.

The positive side to this story then is that a holistic approach to development which meets people’s basic needs can have many beneficial side-effects. By addressing the need for water in day-to-day life, food supply, diets and health can also be positively affected. This kind of synergy is essential if we are to stand a good chance of eradicating poverty and ill-health and meeting the Millennium Development Goals.