Schistosomes are a terrible scourge in Egypt, for just one example. As far as I can tell the
Egyptians h;ave been unable to persuade the people out in the boonies to stop relieving
themselves in way that lets worm eggs get into the water. The eggs hatch, the larva forget
techinical term) parasitize a snail, then new form emerges, that can penetrate skin of anybody
wading in the water, shich the poor people cannot avoid. The effect of the parasite are very
serious, and incapacitating. The economic loss to Egypt is very considerable.