host, through drinking contaminated water, and maintained in the ecosystem in the dry season in the snail Bulinus truncatus.
The flukes, which are larvae, are able to penetrate unbroken skin so that anyone who has regular contact with infested water is at risk. The larvae penetrate a surface vein and work their way through the blood system, into the heart, lungs, liver and abdomen, and thence back into the blood stream where they become adults, which lay eggs that are expelled from the body in blood from the damaged bladder and rectal veins. In the water the eggs hatch into ciliated larvae and search for a snail which they enter through the foot. Within the snail the larvae migrate to the liver and develop into sporocysts (sacs full of eggs) which eventually develop into larvae that break out of the snail as liver flukes. The whole process in the snail takes about three months or longer, allowing the S. haematobium to survive when its water habitat dries out.
Bilharzia is debilitating because it causes itchy skin and tissue deterioration, it erodes the blood vessels, causes internal bleeding, and the eggs are thought to cause cancer.
The problem for the Niger Delta is that there are no appropriate local controls over water pollution. Even if there were, the Delta is held hostage to the up-stream polluting activities of much of Nigeria and the countries within the Niger Benue basin, which include: Cameroon, the Benin Republic, Burkina Faso, Niger, Mali and Guinea.
Sources of Water Pollution
These include:
- domestic sewage and other organic wastes;
- infectious disease bacteria;
- fertiliser residues;
- pesticides and insecticides;
- industrial effluents;
- eroded sediments;
- other solid waste; and
- Petroleum.
Sewage and other organic wastes not only spread disease but also in decomposition have a high biological oxygen demand which may starve aquatic life of oxygen, particularly in the dry season when water movement is sluggish. Because of high water tables, pit latrines are difficult to construct in the Fresh and Brackish-water, and Sand Barrier Island ecozones. Thus public toilets float on the water beside settlements and human faeces falls directly into the water, often within yards of water collection points down-stream. In some districts bathhouses are part of the public toilets so that people immerse themselves in water that is separated from toilet water by no more than a few rotting planks. Ironically, these designs are recommended by the local authority, while simple technology exists to build healthy latrines in high water-table conditions on land.
Agricultural residues are not yet a major problem from within the Niger Delta. However, along with industrial effluents, they will increasingly become a problem arising up-river as Nigeria and the other counties in the Niger basin use more fertiliser and
