Metrifonate, targeting schistosome acetylcholinesterase (AChE) was shown to be effective in killing Schistosoma haematobium [6] but not S. mansoni; it was withdrawn from the World Health Organization’s (WHO) list of essential drugs for treating schistosomiasis [7] because of unacceptable toxicity to the host and the variable efficacy against different schistosome species [8]. This evidence concerns the gene ACHE and schistosomiasis.