Harmonization of regulatory guidelines on efficacy of ectoparasiticides for companion animals: status and missing points.

Ectoparasites of major clinical significance in companion animals include fleas, ticks, lice, mange, mite, mosquitoes and sandflies, as well as biting flies. Obtaining a marketing authorization (or licence) for an ectoparasiticide relies on the assessment by regulatory agencies of a comprehensive data package to confirm the quality, safety and efficacy of the product when used in the target animal species for the proposed claims. Such approval is done under a highly regulated system. However, the global regulatory framework for pet ectoparasiticides is complex, since these products may be classified either as pesticides or as pharmaceuticals depending on the country or even within a given country, based on the presentation or mode of action. Within each jurisdiction, regulatory guidelines provide standards relating to study designs, relevant parasite species, efficacy calculation and acceptable thresholds, and define the corresponding acceptable label claims. Despite some similarities, there is no formal international harmonization for development requirements. In some areas, gaps and/or inconsistencies are more marked than others. Published recommendations from scientific expert groups (e.g. W.A.A.V.P. guidelines) are therefore a useful tool for regulatory bodies, researchers, developers and animal health companies. These expert recommendations reflect the current position of the scientific community and potentially address aspects not covered satisfactorily by regulatory texts while taking into account the latest advancements in experimental methodologies. Since the changes to official regulatory texts generally occur at a slower pace than the scientific state-of-the-art, and because of the lack of a harmonized approach, both scientific and regulatory guidance documents are necessary. The main objective of this review is to explore the complexity of the international regulatory framework for pet ectoparasiticides and to highlight some areas that are insufficiently addressed, or where differences are found between jurisdictions. These gaps and differences may lead to barriers in product development, and to scientific or user confusion. The need of further harmonization effort with the support of parasitology expert working groups is thus advocated.