Cercariae reach the portal venous system several days post-infection Footnote3. 4-6 weeks usually pass before egg production begins Footnote3. Toxemic schistosomiasis may develop 6-8 weeks post infection Footnote5. Urinary schistosomiasis may develop 10-12 weeks post infection Footnote5. Adult schistosomes may live 20 to 30 years.