In certain parts of South Africa a varying proportion of the population suffers from hematuria, caused by the presence in the urine of numerous spine-pointed eggs. The condition is due to a trematode worm, Schistosoma, which inhabits the blood-vessels of the bladder and portal system. It is especially prevalent among the school children of the low veldt, and careful analysis of certain schools has shown that 80 per cent. of the boys and one in ten of the girls are infected.
Many of the young persons who harbor the Bilharzia worm complain of no other sympton than that of hematuria; but in most instances this is remarkably protracted and, when the more obvious signs of the disease have disappeared for many years, ova may still be present in the urine. In the severer forms of the disease patients complain of constant or occasional aching pains in the back, pain on