Diagnostic value of the molecular detection of Sarcoptes scabiei from a skin scraping in patients with suspected scabies

PLoS Negl Trop Dis. 2020 Apr 7;14(4):e0008229. doi: 10.1371/journal.pntd.0008229. eCollection 2020 Apr.

Abstract

Scabies is a highly contagious parasitic disease associated with long-term residence in nursing homes, and it is a public health burden worldwide. However, atypical skin manifestations are frequent and the widely used diagnostic test based on microscopic examinations has limited sensitivity. We evaluated the diagnostic value of polymerase chain reaction (PCR) from skin scraping in patients with suspected scabies. Adult patients with suspected scabies, unrelated diseases or healthy volunteers were enrolled at a tertiary hospital, in Seoul, South Korea, from December 2017 through October 2018. We classified participants based on the consensus criteria established by the International Alliance for the Control of Scabies in 2018; confirmed (microscopic mite detection), clinical (scabies burrow or typical lesions with two history features including itch and close contact with scabies patients), suspected scabies (typical lesion with one history feature or atypical lesion with two history features), or no scabies. PCR was performed on the skin scrapings to target the cytochrome c oxidase subunit 1 (cox1) gene of Sarcoptes scabiei. A total of 47 participants, 33 with suspected scabies, 10 with unrelated diseases, and 4 healthy volunteers were enrolled. Of the 33 patients, 22 were classified as confirmed scabies, 2 as clinical scabies, 6 as suspected scabies, and 3 as no scabies. The sensitivities of the microscopic examination were 100%, 92%, and 73% in confirmed scabies; confirmed and clinical scabies; and confirmed, clinical, and suspected scabies, respectively (p = 0.006). The sensitivities of PCR were 86%, 83%, and 80% in confirmed scabies; confirmed and clinical scabies; and confirmed, clinical, and suspected scabies, respectively (p = 0.59). The specificity of the scabies PCR in the no scabies control was 100% (95% CI = 80-100).PCR testing for scabies may be helpful in the improvement of sensitivity for the diagnosis of scabies by clinical criteria.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Animals
  • Cross-Sectional Studies
  • Electron Transport Complex IV / genetics*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Molecular Diagnostic Techniques / methods*
  • Polymerase Chain Reaction / methods*
  • Prospective Studies
  • Republic of Korea
  • Sarcoptes scabiei / enzymology*
  • Sarcoptes scabiei / genetics
  • Scabies / diagnosis*
  • Sensitivity and Specificity
  • Skin / parasitology*
  • Specimen Handling / methods*
  • Tertiary Care Centers

Substances

  • Electron Transport Complex IV

Grants and funding

This work was supported by grants from Korean Society for Chemotherapy (http://www.ksat.or.kr/) to JJ in 2018 and the Korea Health Technology R&D Project through the Korea Health Industry Development Institute, funded by the Ministry of Health & Welfare, Republic of Korea to S-HK (grant no. HI16C0272). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.