Fungal Skin Disease (Tinea, Dermatophytosis): Causes

Pathogenesis (development of disease)

Pathogenic fungi can be divided into dermatophytes (filamentous fungi), shoot fungi (yeasts), and molds.

Classification of fungi

Skin fungi Dermatophytes
Sprout fungi (yeasts) Candida, Cryptococcus
Molds Alternaria, Aspergillus (aspergillosis), Mucorales, Mucor, Rhizomucor, Rhizopus,

Infections with dermatophytes – Trichophyton, Microsporum, Nannizzia, and Epidermophyton – can result in various skin and nail lesions depending on the affected body region:

  • Trichophyton spp.: affects skin, nails and hair and also occurs in pets (zoophilic).
  • Microsporum spp.: affects skin and hair and also occurs in pets (zoophilic).
  • Nannizzia: affects skin; occurrence in soil; e.g., a gardener falls ill with tinea manuum.
  • Epidermophyton floccosum: affects skin and nails.

Ports of entry for dermatophytosis (filamentous fungal disease) are often small injuries to the skin, especially at the interdigital spaces (space between two fingers or toes). In the genitoanal region, dermatophytes most commonly affect the inguinal and gluteal regions (groin and buttock regions). Spread to other skin areas is possible.

If the mucous membranes are affected, it is usually candida yeast (candidosis, candidiasis).

In tinea corporis and tinea capitis, the pathogen is often Microsporum canis.

In pityriasis vesicolor, Malassezia furfur is the causative agent.

Etiology (causes)

Behavioral causes

  • Use of common facilities such as showers, bathrooms.
  • Athletes
    • Wg. high exposure for dermatophyte-related mycoses (e.g., swimming and mat athletes).
    • Anthropophilic Trichophyton ( T.) tonsurans (“Tinea gladiatorum”) in contact sports.
  • Pets: cats, dogs or guinea pigs (source of Microsporum canis; zoophilic dermatophytosis); transmitted during cuddling with “cuddly toys” → Tinea capitis, Tinea corporis.
  • Playing with stuffed animals and other plush objects (reservoir of Microsporum canis or Trichophyton tonsurans).
  • Overweight (BMI ≥ 25; obesity).

Disease-related causes

Endocrine, nutritional, and metabolic diseases (E00-E90).

Cardiovascular system (I00-I99)

  • Circulatory disorders, unspecified

Infectious and parasitic diseases (A00-B99).

  • HIV/AIDS

Musculoskeletal system and connective tissue (M00-M99).

  • Foot deformities (tinea pedis)

Psyche – nervous system (F00-F99; G00-G99)

  • Peripheral neuropathy – nerve damage to the nerves affecting the extremities (tinea pedis).

Injuries, poisonings and other consequences of external causes (S00-T98).

  • Trauma (injury), unspecified (e.g., tinea pedis: usually caused by anthropophilic dermatophyte Trichophyton rubrum)
    • Tinea genitalis due toDamage to the epithelial barrier by regular shaving of the genital area.
    • Dermatophyte-related mycoses (esp. of the toenails (onychomycosis)) due tomicrotrauma of the skin in running athletes.

Other causes

  • Dialysis patients
  • Transplanted
  • Tumor patients

Medication