Scabies polymerase chain reaction with standardized dry swab sampling: an easy tool for cluster diagnosis of human scabies

Authors:
Publisher website
Google Scholar
Abstract
Background Expert visualization of Sarcoptes scabiei remains essential for diagnosing human scabies but access to experts can be difficult. PCR is a very specific tool for the detection and confirmation of Sarcoptes scabiei but this test has a poor sensitivity because of the requirement of previous expertise when collecting appropriate samples to gain a positive result. Objective Evaluate PCR as a diagnostic method for scabies using non expert‐dependent standardized sampling. Methods The dry swab was systematically rubbed across the front of both wrists, the eight interdigital spaces and on any suspected scabies lesions in all patients referred for scabies. A new PCR‐based diagnostic test was run on the samples. All patients underwent clinical and dermoscopic examination. Scabies diagnosis was confirmed when dermoscopic examination was positive or the patient had typical clinical signs of scabies. Results Of 183 suspected scabies patients, 164 patients were sampled, 87 had confirmed scabies (dermoscopy positive n=87, typical clinical sign n=1) and 77 did not. Of the 87 patients with proved scabies, 33 patients had positive scabies PCR resulting in a 37.9% (95% CI=28.4‐48.4%) sensitivity and a 61.7%. (95% CI=52.4‐72.7%) Negative Predictive Value. None of the 77 patients ruled out for scabies had a positive PCR result. Conclusion This method is non‐traumatic, repeatable, non‐expert‐dependent. It shows sensitivity similar to previous studies involving expert skin scraping. However, this method facilitates the multiplication of sampling which increased sensitivity for cluster scabies diagnosis. This method may be suitable as a first line diagnosis tool for suspicion of large cluster scabies outbreak.

This publication has 14 references indexed in Scilit: