Schistosomiasis is the 2nd most common parasitic disease that causes around 300000 deaths annually worldwide. The main antischistosomal therapy; praziquantel (PZQ) has many imperfections e.g. resistance, frail impact against premature stages and many side effects. This raised the need to find a substitute or to repair PZQ defects. This work aimed to assess value of loading PZQ to chitosan nanoparticles (CS-NPs) regarding usage of lower PZQ dose (to decrease side effects) and broadening its spectrum (to involve premature stages of Schistosoma mansoni). This study involved 11 mice groups. The first four groups served for schistosomula studies (mice were euthanized 17 days post infection (d.p.i.). Group I served as positive schistosomula controls. Groups II, III and IV received pre-maturation treatments 10 d.p.i. The last seven groups served for adult worm studies (mice were euthanized 50 d.p.i.). Group V served as positive adult controls. Groups VI, VII and VIII received pre-maturation treatments 10 d.p.i. Groups IX, X and XI received post-maturation treatments 45 d.p.i.
Drug efficacy against schistosomula was assessed by counting and scanning electron microscopy (SEM) of the retrieved schistosomula. Efficacy against adult worms was assessed by studying worm load, ova count, oogram, granuloma studies and SEM of adult worms. Results showed that, PZQ loaded CS-NPs (PZQ/CS-NPs) significantly reduced schistosomula count with no morphological changes. Regarding adults, PZQ/CS-NPs achieved a statistically significant higher reduction of all assessed parameters - compared to traditional PZQ - especially when administered as a post-maturation treatment. Regardless of absent morphological changes of schistosomula, clear morphological deformities appeared when these schistosomula were permitted to develop into adults.