Multiple sclerosis: what can and cannot be done.

trivial, I would like to point out that dracunculiasis is not acquired either by ingesting or by contact with snails but by drinking water containing infected Cyclops species, which are small (1-2 mm) freshwater crustaceans. In man the mature female worm discharges firststage larvae (not eggs) at the surface of the skin, usually when the affected part of the body (commonly the foot and lower leg) comes into contact with water. These first-stage larvae are extremely active and can live for four to seven days; their further development, however, depends on their being eaten by a predatory species of Cyclops. The larvae penetrate the gut of the Cyclops and after two moults in the haemocoel reach the infective third stage.' Dracunculiasis today is mainly a disease of rural communities. D ROLLINSON