Praziquantel is specifically a schistosomicide - the drug of choice for treating schistosomiasis (bilharzia). It is not used for tapeworms (niclosamide/albendazole), threadworms (albendazole/mebendazole), or as a filaricide (diethylcarbamazine/ivermectin). Praziquantel works by causing tetanic paralysis of schistosomes.