361 Ohshima

Schistosomiasis is widespread, especially in Asia, Africa and Latin America (IARC, 1994, Ross et al., 2002). A report of the World Health Organization in 1993 estimated that 200 million people were infected with schistosomes and that 600 million people were at risk of infection in 74 countries (WHO, 1993). Although in recent years the endemic areas have tended to decrease as a result of administration of antischistosomal drugs such as praziquantel and new strategies for prevention, rapid reinfection poses a threat to younger age groups due to the slow maturation of natural resistance (Wu et al., 1994; Etard et al., 1995; Jiang et al., 1996; Ross et al., 2002). Epidemiological studies have associated schistosome infection with increased risk of cancers of the liver, colon Altered Expression of Fas (APO-1, CD95) and Fas Ligand in the Liver of Mice Infected with Schistosoma Japonicum and Schistosoma Mansoni: Implications for Liver Carcinogenesis