Immune response and pathogenesis of neuroschistosomiasis mansoni.

The involvement of the central nervous system (CNS) by schistosomes may or may not determine clinical manifestations. When symptomatic, neuroschistosomiasis (NS) is one of the most severe presentations of schistosome infection. Considering the symptomatic form, Schistosoma mansoni causes almost always spinal cord disease. Cerebral and spinal cord disorders in S. mansoni infections are inflammatory conditions of the CNS that cause mild-moderate impairment of the blood-brain barrier and intrathecal synthesis of antibodies against schistosomal antigens. Little is known about the pathogenesis of NS, but available evidence strongly suggests that it depends basically on the presence of parasite eggs in the nervous tissue and on the host's immune response against the trapped eggs. Numerous eggs surrounded by granulomas lodged together in circumscribed areas of the CNS damage the nervous tissue by both the mass effect and the egg-induced inflammatory reaction. Vasculitis of immune etiology, which causes isquemic lesions, may also play an important role in the genesis of the neurological symptoms. Although the mechanisms involved in the immunophatogenesis of NS are largely unknown, initial investigations on cerebrospinal fluid (CSF) and serum cytokine profiles suggest the occurrence of inflammation as well as a skewed Th2 immune response that probably occur both locally and systemically.