Parasite's mouth. Coloured scanning electron micr- ograph (SEM) of red blood cells (red) in the mouth of a Schistosoma mansoni fluke, a parasite causing the disease bilharzia (schistosomiasis). It lives in the veins of the intestines and bladder of humans. It feeds on blood cells, attaching itself to blood vessel walls using a suction pad (not seen). Females lay eggs which are excreted in urine and faeces into lakes and rivers. In water snails, they develop into forms which can penetr- ate human skin, spreading the disease. Bilharzia is endemic in tropical countries, and causes liver and kidney damage if untreated. It is treatable with drugs. Magnification: x830 at 6x7cm size.