Scabies: Molecular Perspectives and Therapeutic Implications in the Face of Emerging Drug Resistance

Kate E. Mounsey; Deborah C. Holt; James McCarthy; Bart J. Currie; Shelley F. Walton


Future Microbiol. 2008;3(1):57-66. 

In This Article

Future Perspective

In light of emerging drug resistance, the use of alternative agents should be considered. For example, benzyl benzoate and crotamiton are both very effective acaricides in vitro and could be revisited in the clinical setting. However, this is hampered by the fact that few robust clinical trials exist for scabies treatments, and this needs to be addressed as a matter of priority. Tea tree oil is a promising new topical therapy, particularly when used in combination with other treatments. Not only may this be associated with improved treatment outcomes, but combination therapies could become increasingly useful and important in the event of increasing drug resistance.

One of the current difficulties in assessing drug resistance is limited access to mites with a clear resistance phenotype. Studies are currently restricted to mites obtained from the clinical setting, and therefore there are inevitable confounders, such as physiological factors and co-administration of other drugs, making definition of true resistance difficult. Fortunately, the further development of an animal model for human scabies is currently being attempted and may become available in the near future. The generation of laboratory selected drug-resistant strains will open up a new realm of possibilities, allowing the consolidation of recent molecular progress with phenotypic changes potentially associated with developing resistance.

The deleterious impact of scabies in developing regions worldwide is without question. We are now rapidly making advances in our understanding of the genetics of S. scabiei, with the characterization of key genes potentially associated with permethrin and ivermectin resistance. This will enable the development of molecular techniques to facilitate the continued monitoring, and enable the identification of emerging permethrin and ivermectin resistance in scabies endemic communities. This is important in light of increasing pressure from health professionals to begin mass intervention programs with ivermectin in endemic areas.


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