Hidden scabies: diagnosis by polymerase chain reaction.

Diagnosis of scabies infection can be difficult as in many cases only few mites are present on an infected person, and in some cases the skin manifestations can be subtle or atypical. We describe the use of polymerase chain reaction (PCR) to amplify Sarcoptes scabiei DNA in a patient presenting with clinically atypical eczema. Cutaneous scales were PCR positive for S. scabiei DNA before, and negative 2 weeks after, therapy. This method facilitates fast and very sensitive diagnosis of clinically atypical or inapparent scabies infection and therapy control in severely affected patients and may help to identify previously unrecognized scabies cases.