What causes groin ringworm (tinea cruris)?

Groin ringworm, clinically known as tinea cruris, is primarily caused by fungal infection. Fungi such as Trichophyton rubrum and other dermatophytes can adhere to or colonize on the skin after coming into contact with the groin area, penetrate the stratum corneum cells, and trigger an inflammatory response. The occurrence of tinea cruris is closely related to multiple factors, including: 1. Damp local environment: The groin area is prone to dampness, providing favorable conditions for fungal growth. 2. Decreased immunity: Individuals with weakened immune systems are more susceptible to fungal infections. 3. Personal hygiene habits: Poor hygiene practices, such as not changing underwear regularly or failing to keep the groin area clean, can also increase the risk of infection. 4. Transmission factors: Tinea cruris can spread through one's own hands, feet, or nails affected by fungal infections (e.g., tinea manus, tinea pedis, onychomycosis), and can also be transmitted through contact with infected individuals, their personal items, or animals infected with fungi.