Schistosoma mansoni: the effect of dexamethasone on the cercaria-schistosomulum transformation, in vivo

Abstract

Treatment with dexamethasone (DMS) in the early phases of the experimental Schistosoma mansoni infection causes an indirect effect on the cercaria-schistosomulum transformation process. This is observed when naive albino mice are treated with that drug (50 mg/Kg, subcutaneously) and infected intraperitonealy 01 hour later with about 500 S. mansoni cercariae (LE strain). An inhibition in the host cell adhesion to the larvae, with a simultaneous delay in the cercaria-schistosomulum transformation, is observed. This effect is probably due to a blockade of the neutrophil migration to the peritoneal cavity of mice, by an impairment of the release of chemotactic substances. Such delay probably favors the killing of S. mansoni larvae, still in the transformation process, by the vertebrate host defenses, as the complement system.

Phenotypic plasticity of maleSchistosoma mansonifrom the peritoneal cavity and hepatic portal system of laboratory mice and hamsters

“…As an advantage, peritoneal infection allows a simple and rapid method for mass screening of prophylactic agents to combat schistosomiasis (Pereira et al , 1974). This method of study has also helped to elucidate aspects of the early stages and immunology of the host–parasite relationship (Melo et al , 1978, 1980, 1993a, b, 1994; Melo & Pereira, 1980, 1985; Chao et al , 1986). Indeed, it has been demonstrated that parasites recovered from the peritoneal cavity of two albino mouse strains (AKR/J and Swiss) are significantly different in relation to the total body length of the worms, the intraperitoneal worm burden and the maturation degree of the schistosomes (Bicalho et al , 1993).…”