Ringworm (Dermatophytosis): Fungal Types, Transmission Routes, Prevention, and Treatment Options

Ringworm is a misnomer—it's a superficial fungal infection caused by dermatophytes (keratin‑feeding fungi), not worms.

Causative Genera

Genus	Primary Reservoir	Common Presentations
Trichophyton	Human (anthropophilic), animals, soil	Tinea corporis, pedis, cruris, capitis, unguium
Microsporum	Animals (zoophilic), especially cats/dogs	Tinea capitis, corporis
Epidermophyton	Human only	Tinea pedis, cruris

Malassezia causes pityriasis versicolor and folliculitis—distinct from classic ringworm.

Transmission

• Direct skin‑to‑skin (human or animal)
• Fomites: towels, clothing, combs, gym mats, wrestling mats
• Soil (geophilic species)

Pathogenesis

Fungi secrete keratinases, invade stratum corneum. Asexual reproduction (conidia) spreads infection centrifugally → classic annular, scaly, advancing border with central clearing.

Prevention

• Keep skin clean/dry; avoid sharing personal items.
• Treat infected pets promptly.
• Footwear in locker rooms/pools.
• Launder sports gear in hot water.

Treatment

• Topical azoles/terbinafine (2–4 weeks) for limited disease.
• Oral terbinafine/itraconazole/griseofulvin for extensive, scalp, nail involvement.

Diagnosis confirmed by KOH prep, culture, or PCR.