The occurrence of dorsal bare area and ventro-lateral scales was studied in Sarcoptes scabiei (Linnaeus) females from three types of infestation: Norwegian Scabies (W.S S.I strain), an epidemic outbreak of classical scabies (HSC strain) and swine scabies (P strain). The presence of dorsal bare area did not differ between W,S S.l and HSC strains, but there was a difference between the human strains and P strain. Ventro-lateral scales were not seen in P strain, but it was possible to identify them in one W. S S. 1 strain female. The variability among strains difficults the identification of parasite morphology-host-clinical relationships.
