Praziquantel is the major drug used to treat people infected with parasitic worms that cause schistosomiasis. However, the mechanism of action of praziquantel remains unclear. Nogi et al. (doi:10.1371/journal.pntd.0000464) identify a new biological activity of this drug to subvert regenerative polarity in a planarian to produce two-headed flatworms. By using this striking phenotype as a screen for molecules regulating in vivo praziquantel efficacy, the authors provide genetic evidence supporting the calcium channel hypothesis of praziquantel action.

Image Credit: Jonathan Marchant, University of Minnesota