Equis ISSN 2398-2977

Trichophyton spp

Contributor(s): Susan Dawson, David Senter, Richard Walker, Beatrice Funiciello

Introduction

Classification

Taxonomy

  • Genus: Trichophyton.
  • Species: benhamiae, bullosum, concentricum, equinum, eriotrephon, erinacei, interdigitale, mentagrophytes, quinckeanum, rubrum, schoenleinii, simii, soudanense, tonsurans, verrucosum and violaceum
  • Sexual form: sometimes present, Arthroderma-like.

Etymology

  • Gk: trikho - hair; phyton - plant.

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Clinical Effects

Epidemiology

Habitat

  • T. equinum has its reservoir in equine skin.
  • Other trichophyton species inhabit other mammalian hosts (zoofilic dermatophytes).

Can transfer to in-contact humans Trichophyton: lesion 01 - human (ringworm)Trichophyton: lesion 02 - human (ringworm).

Transmission

  • Direct and indirect (fomite) contact.

Pathological effects

  • Antibody-mediated and cell-mediated hypersensitivities involved in pathogenesis.
  • Antibodies do not seem important in protection.
  • Recovered animals are resistant to reinfection unless a different dermatophyte is involved.
  • If reinfection occurs the lesions are usually smaller and quicker to resolve.
  • Proteolytic enzymes  →  virulence.
  • Infectious conidium enters through skin defect  →  germination  →  mycelium develops in cornified epithelium  →  hair invasion  →  ectothrix arthroconidial accumulation.
  • Site of lesions depends on reservoir and transmission, eg T. erinacei (the reservoir host being the hedgehog) occurs on muzzle, face, front paws and legs of dogs which worry hedgehogs.
  • T. equinum survives in fomites such as tack and grooming equipment and so occurs in horses in those areas that come into contact  Dermatophytosis.

Other Host Effects

  • Some species have become adapted for survival in the skin of specific host species, ie they are zoophilic, eg T. equinum (horses), T. erinacei (European hedgehogs), T. mentagrophytes (rodents), T. verrucosum (cattle).

Control

Control via chemotherapies

  • Spontaneous regression without treatment is common (1-4 months in immunocompetent horses).
  • Topical:
  • Oral: griseofulvin  Griseofulvin but not routinely used.

Topical treatment may decrease spread, severity and duration of lesions.

Control via environment

  • Avoid contamination of fomites, eg grooming kit.

Vaccination

  • In cattle; has been attempted experimentally in horses.

Diagnosis

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • de Hoog G L, Dukik K et al (2017) Toward a novel Multilocus Phylogenetic Taxonomy for the Dermatophytes. Mycopathologia 182 (1-2),  5-31 PubMed.

Other sources of information

  • Scott D W & Miller W H Jr (2011) Diagnostic Methods. In: Equine Dermatology. 2nd edn. Saunders, USA. pp 35-100.
  • Scott D W & Miller W H Jr (2011) Fungal Skin diseases. In: Equine Dermatology. 2nd edn. Saunders, USA. pp 171-211.
  • Biberstein E L (1990) Dermatophytes. In: Review of Veterinary Microbiology. Eds: E L Biberstein & Y C Zee. Blackwell Scientific, USA. pp 272-279. ISBN: 0 86542 085 8.

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