Athlete’s foot (tinea pedis) is a common fungal infection causing discomfort like itching, scaling, and burning on the feet. It is caused by dermatophytes, a group of fungi that thrive in specific environments. After successful treatment, preventing recurrence is a primary concern, often involving whether footwear retains the infectious agent. Shoes can harbor the fungus, and decontaminating them is necessary to avoid reinfection.
Why Shoes are a Fungal Incubator
The fungi responsible for athlete’s foot rely on keratin, a structural protein found in skin, hair, and nails. Dermatophytes feed on this protein, which is readily available in skin flakes shed from an infected foot. They require specific conditions to grow and multiply.
The interior of a shoe, particularly athletic shoes, creates a near-perfect microclimate for these organisms. This enclosed space is warm, dark, and frequently moist from perspiration. This combination provides the ideal breeding ground, allowing the dermatophytes to flourish. Footwear collects the infectious agents and keeps them viable for future contact.
How Long the Fungus Survives Outside the Body
The fungus does not remain actively growing once it is outside the body and away from the host skin. However, the organism protects itself by forming resilient structures called spores. These spores are the primary source of reinfection, shed into the shoe lining, where they survive in a dormant state for extended periods.
Under dark and moist conditions, such as inside a damp shoe or sock, these fungal spores can remain viable for weeks. In less ideal conditions, like a dry, well-ventilated environment, their lifespan is reduced, yet the spores can still persist for several days. Under optimal conditions, fungal spores can survive in materials like shoe liners or textiles for months. The material of the shoe also plays a role, as porous fabrics and synthetic materials can trap moisture and spores more easily than breathable leather.
Practical Steps for Decontaminating Footwear
A multi-pronged approach is necessary to eradicate fungal spores and prevent reinfection. Chemical treatments applied directly to the shoe’s interior are one direct method. Antifungal sprays and powders designed for footwear should be applied to the insoles and lining, as these products are formulated to kill persistent spores.
Temperature treatments are effective, especially for socks and removable insoles. Washing socks and cloth insoles in hot water, specifically 60°C (140°F) or higher, is necessary to neutralize the spores. For the shoes themselves, environmental control is safer than using extreme temperatures that could cause material damage.
Thorough drying and ventilation are effective ways to disrupt the fungi’s preferred microclimate. After wearing shoes, they should air out completely for at least 24 hours before being worn again. Rotating between multiple pairs allows each pair sufficient time to dry, eliminating the moisture needed for spores to become active. Exposing the shoe’s interior to direct sunlight or utilizing an ultraviolet (UV) light shoe sanitizer can help destroy fungal spores.