Pragmatic efficacy against conceptual precaution in parasite control: The case of avermectins.

Avermectins, a class of molecules originating from the microbial Streptomyc es avermetilis, exhibit anthelmintic, nematicide and insecticide activity. Their action is mediated at least through interaction with chloride channel s at neuromuscular junction. They provide substantial control of parasite w orms in human and animals, but their effects are not total, while both para site resistance and host side-effects are observed. Therefore, eradication is hardly realistic, and control should be focused on safest conditions for the limitation of parasite upsurge and transmision. Further more, while a break of intra-parasite competition may in some cases induce unexpected adv erse results, ecotoxicity from environmental release has started being docu mented. Within the context of understanding of ecosystem function, the role of any specie should be understood as completely as possible prior to plan ning for its elimination. This is fully consistent with the precaution acti on principle.