Schistosomiasis with special references to the mechanisms of evasion

Abstract

Schistosomiasis is a disease caused by infection with Schistosoma spp. It affects 200 million \npeople worldwide, especially in the developing countries. There are five known species of \nSchistosoma which currently infect humans in various geographical locations. Infection with \nSchistosoma spp. leads to two forms of the disease: acute and chronic. Chronic infection \ncan affect various organs within the human body including the brain, lungs, gut and the \nreproductive organs, which leads to neuroschistosomiasis, pulmonary schistosomiasis, hepatointestinal schistosomiasis and urinary genital schistosomiasis, respectively. All Schistosoma \nspp. have a common denominator that they have the ability to infect, invade and evade the \nhost’s immune mechanism. Schistosoma sp. is a very complex organism that requires two \nhosts, mollusk and mammalian, to survive, propagate and complete its life cycle. Hence, it \nhas developed specific immune evasion mechanisms for each of them. Once Schistosoma \nsp. has infected and established itself within its mammalian host as an adult worm, it evades \nthe immune mechanism of that host. However, the antigens released by the eggs can elicit an \nimmune response with formation of granuloma around eggs. Granuloma formation is the main \ncharacteristic lesion in schistosomiasis, which in the liver can cause hepatomegaly in hepatointestinal schistosomiasis. This paper will summarize various immune responses against the \nparasite as well as vari…