experimental study of CNS schistosomiasis: histopathological and immunological aspects

ABSTRACT

The brain and spinal cord tissues of 54 albino Swiss mice, heavily infected with S. mansoni cercariae were examined histologically using hematoxylin and eosin stains, as well as, immunologically using the direct immunofluorescent technique. Histopathological examination revealed inflammatory mononuclear cells infiltration which was variable in its cellular composition, pattern, severity and site of infiltration, vascular changes in the form of vasculitis, intimal proliferation and/or thickened, hyalinized media with congested blood vessels and associated edema and gliosis. These histopathological changes were prominent in the early acute stage of infection with subsequent spontaneous gradual diminution as passing to chronicity. The direct immunofluorescent study revealed IgG deposits in the CNS of the infected mice. The positive immunofluorescent reaction started to develop in the early acute stage of infection and reached its maximal levels around 11[th] week of infection with subsequent spontaneous gradual diminution. No ova or adult worms could be visualized in the histologic sections or by fluorescent technique. The CNS involvement in the course of schistosomiasis mansoni infection is not necessarily dependent on the direct action of ectopic ova and the resultant granuloma formation. An immunological reaction is an alternative mechanism, through which the CNS may be involved. This immune reaction usually occurs during the early acute stage of infection with subsequent gradual spontaneous diminution. However, some cases with such reaction may be at risk of the development of chronic immune- complex disease, which may be at least in part, responsible for neurological complications seen in some cases with advanced chronic schistosomal infection