Contribution of silver ions to the inhibition of infectivity of Schistosoma japonicum cercariae caused by silver nanoparticles.

SUMMARY Blockageofpathogentransmissionthroughwaterdecontaminationisconsideredanimportantstrategyforthepreventionofschistosomeinfection.Manybelievethatthisstrategyisfeasible,butithasyettobeachieved.Silverhasalonghistoryofuseas a disinfectant. With the emergence of nanotechnology, silver can be shaped into nanoparticles which have been found topossess superb antimicrobial activities. In this light, we investigated the effects of silver nanoparticles (AgNPs) onSchistosoma japonicum cercariae. AgNPs rapidly induced cercarial tail-shedding, agitated behaviour and a decrease incercarial secretion in a dose-dependent manner. Prolonged treatment was found to be cercariocidal, which neverthelessmight be attributable to AgNP-induced cercarial tail loss rather than to toxicity. Higher concentrations of AgNPs(125μgmL −1 and above) completely blocked cercarial infectivity. Despite decreased infectivity, cercariae exposed to lowerconcentrations of AgNPs for 30min were still found capable of infecting hosts even without their tails, suggesting that tailloss does not necessarilysignifyatotalloss of infectiveability. Wealso foundthatsilverions (Ag