Simple preservation of schistosome eggs with high infectivity up to 12 weeks.

The lifecycle of schistosomes must be continuously maintained to clarify and understand this parasite in various aspects in laboratory settings. In the previous studies by other researchers, preservation of schistosome larvae or eggs was attempted by freezing with liquid nitrogen or organic chemicals, but frozen schistosomes were substantially impaired. The present study was conducted to determine whether schistosome eggs can be preserved under a non-frozen condition. The results showed that Schistosoma mansoni eggs could be maintained in phosphate-buffered saline at 4 °C, with a high level of infectivity of miracidia to freshwater snails thereafter. Furthermore, the egg hatchability was maintained for up to 12 weeks with weekly exchanges of the medium. The cercariae derived from snails infected with miracidia from preserved eggs were highly infective to mice. This simple schistosome egg preservation method allow researchers to maintain the schistosome lifecycle without freezing or other special procedures.