Njagi, E.N.M.Bender, D. A.2014-07-222014-07-221991(Kynurenine and Serotonin Pathways Progress in Tryptophan Research978-1-4684-5954-8978-1-4684-5952-40065-2598http://ir-library.ku.ac.ke/handle/123456789/10536DOI 10.1007/978-1-4684-5952-4_53Biharzia due to infection with Schistosoma mansoni is a major and increasing problem in tropical countries, associated especially with irrigation schemes, which provide a habitat for the water snail which is the alternate host of the parasite. Infection results from bathing or other contact with water containing infected snails, which release large numbers of cer-cariae, the infectious form which penetrates human skin.enBook chapter