Felis ISSN 2398-2950

Skin: Wood's lamp test

Contributor(s): Rosanna Marsella, Ian Mason, David Scarff, Catherine Fraser

Introduction

  • The tryptophan metabolites of certain dermatophytes, eg Microsporum canis Microsporum canis, fluoresce under ultra-violet light of 330-365 nm wavelength.
  • A Wood's lamp is a source of ultraviolet light filtered through a cobalt or nickel filter.
  • Microsporum canis is a major cause of dermatophytosis Dermatophytosis in veterinary medicine.

Uses

  • Screening for Microsporum canis infection.
  • Selection of appropriate hairs for culture.
    Positive Wood's lamp examination is only suggestive, not diagnostic of Microsporum canis Microsporum canis infection.Negative Wood's lamp examination does not rule out Microsporum canis infection.

Advantages

  • Rapid screening technique.

Disadvantages

  • Not all strains of Microsporum canis fluoresce - 30-80% show positive fluorescence.
  • Medication, eg iodine, destroys fluorescence.
  • Only actively infected growing hairs fluoresce.

Requirements

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Preparation

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Procedure

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Rezabek G H & Friedman A D (1992) Superficial fungal infections of the skin. Diagnosis and current treatment recommendations. Drugs 43 (5), 674-682 PubMed.
  • Caplan R M (1967) Medical uses of the Wood's lamp. JAMA 202 (11), 1035-1038 PubMed.


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