DNA studies of Egyptian mummies shows evidence of the existence of Schistosomiasis about 5000 years ago. Schistosomiasis is increasing in prevalence, affecting nearly 10% of the world’s population and ranking second only to malaria as a cause of morbidity & mortality. Schistosoma haematobium are found in tropical Africa & part of southwest Asia. Schistosoma mansoni are found in tropical Africa, part of southwest Asia, south America & Caribbean islands. Schistosoma japonicum are found in parts of Japan, China, Philippines, India & part of southeast Asia. Blood flukes are known as schistosomes because of the "split body" on the ventral side of the male, in which the female is held during insemination and egg laying. Man is the definite host harbouring adult parasites, and fresh water snails are intermediate hosts.